Office of Transportation

and Air Quality

EPA420-D-06-005

February 2006

California Heavy Heavy-Duty 

Diesel Truck Emissions 

Characterization for 

Program E-55/59

Draft Report
EPA420-D-06-005

February 2006

California Heavy Heavy-Duty Diesel Truck Emissions 

Characterization for Program E-55/59

Draft Report

Assessment & Standards Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

Prepared for EPA by:

Coordinating Research Council (CRC)

NOTICE

This Technical Report does not necessarily represent final EPA decisions or positions.

It is intended to present technical analysis of issues using data that are currently available.

The purpose in the release of such reports is to facilitate an exchange of 

technical information and to inform the public of technical developments.
TABLE OF CONTENTS 

TABLE OF CONTENTS..................................................................................................... i 

LIST OF FIGURES ...........................................................................................................iii 

LIST OF TABLES...........................................................................................................viii 

LIST OF APPENDICES..................................................................................................... x 

LIST OF APPENDICES..................................................................................................... x 

EXECUTIVE SUMMARY ................................................................................................ 1 

NOMENCLATURE ........................................................................................................... 6 

INTRODUCTION AND OBJECTIVES ............................................................................ 7 

VEHICLE PROCUREMENT............................................................................................. 9 

EQUIPMENT & METHODS – REGULATED SPECIES .............................................. 15 

Translab Description..................................................................................................... 15 

Preparation of the Vehicle for Testing.......................................................................... 15 

Engine/Vehicle Preparation .......................................................................................... 16 

Wheel-Hub Adapter Installation................................................................................... 17 

Test Vehicle Mounting ................................................................................................. 17 

Connections of Vehicle to Laboratory.......................................................................... 17 

Pre-test Vehicle Operation............................................................................................ 17 

Vehicle Driving Instructions......................................................................................... 18 

Vehicle Practice Run..................................................................................................... 18 

Test Run Procedures ..................................................................................................... 19 

Gaseous and PM sampling system................................................................................ 19 

Gas Analyzer Operation................................................................................................ 22 

Calibration Procedures.................................................................................................. 22 

Particulate Matter Filter Conditioning and Weighing .................................................. 23 

Test Cycles.................................................................................................................... 23 

Test Weights ................................................................................................................. 27

EQUIPMENT AND METHODS – NON-REGULATED SPECIES & PARTICLE

SIZING ............................................................................................................................. 31 

DRI’s Residence Time Dilution Tunnel ....................................................................... 31 

Mini Dilution System.................................................................................................... 33 

Particle Sizing with the SMPS...................................................................................... 37 

Particle sizing with the DMS500 .................................................................................. 40 

Unregulated Emissions ................................................................................................. 42 

Speciation Fleet and Approach ..................................................................................... 44 

QUALITY ASSURANCE AND QUALITY CONTROL................................................ 46 

RESULTS AND DISCUSSION, REGULATED SPECIES ............................................ 48 

HHDT Data Gathered ................................................................................................... 48 

MHDT Data Discussion................................................................................................ 60 

Continuous Data............................................................................................................ 69 

HHDDT Effect of Test Weight..................................................................................... 72 

MHDT Effect of Test Weight....................................................................................... 74 

COMPARISON OF DATA BETWEEN PHASES .......................................................... 75 

RESULTS AND DISCUSSION, NONREGULATED SPECIES.................................... 78 

Semi-Volatile Organic Compounds.............................................................................. 78 
Volatile Organic Compounds ....................................................................................... 82 

SPECIATION AND SIZING RESULTS ......................................................................... 87 

CONCLUSIONS, NONREGULATED SPECIES ......................................................... 126 

TAMPERING, MALMAINTENANCE AND REFLASH VEHICLES ........................ 131 

T&M Criteria .............................................................................................................. 131 

Determination of Candidates from Vehicle Inspection .............................................. 131 

Determination of T&M Candidate from Emissions.................................................... 132 

Results: T&M by Inspection....................................................................................... 135 

Verifying the Criteria in Phase 1: NOx Analysis ........................................................ 136 

Verifying the Criteria in Phase 1: PM Analysis.......................................................... 137 

Criteria ratios for all phases ........................................................................................ 142 

“Before and After” Emissions .................................................................................... 151 

T&M and Reflash Discussion..................................................................................... 167 

ACKNOWLEDGEMENTS............................................................................................ 170 

REFERENCES ............................................................................................................... 171 

ii 
LIST OF FIGURES 

Figure 1: WVU Sampling System Schematic................................................................... 20 

Figure 2: AC5080 Short Test (time not to scale).............................................................. 26 

Figure 3: The AC5080 Schedule as driven by a 1990 Kenworth road tractor with a 370 hp 

Cummins M11 engine and a 10-speed manual transmission, with a simulated vehicle 

test weight of 56,000 lbs. .......................................................................................... 27 

Figure 4: PM emissions for vehicle E55CRC-27 which was tested at four weights, before 

66,000 lbs. was adopted as the highest test weight................................................... 28 

Figure 5: NOx emissions for vehicle E55CRC-27 which was tested at four weights, before 

66,000 lbs. was adopted as the highest test weight................................................... 28 

Figure 6: PM emissions for vehicle E55CRC-53 tested at two weights........................... 29 

Figure 7: NOx emissions for vehicle E55CRC-53 tested at two weights. ........................ 30 

Figure 8: Schematic of DRI dilution tunnel sampler (Hildemann, et al.6) ....................... 32 

Figure 9: Exhaust Coupler with Sampling Probe for mini dilution tunnel....................... 33 

Figure 10: West Virginia University-Mini Dilution System ............................................ 34 

Figure 11: Schematic Representation of the Damping System ........................................ 36 

Figure 12: Exhaust Pulsation Damper .............................................................................. 36 

Figure 13: Differential Mobility Analyzer........................................................................ 37 

Figure 14: TSI Model 3936 SMPS System ...................................................................... 39 

Figure 15: Working principle of the DMS5008

. ............................................................... 41 

Figure 16: NOx emissions for the Idle Mode, in units of g/minute................................... 49 

Figure 17: NOx emissions for the Creep mode (56,000 lbs.)............................................ 49 

Figure 18: NOx emissions for the Transient mode (56,000 lbs.). One of the vehicles in the 

1975-1976 MY bin emitted NOx at 60 g/mile. ......................................................... 50 

Figure 19: NOx emissions for the Cruise mode (56,000 lbs.). One 1998 vehicle (E55CRC10) was identified as a high NOx emitter in Phase 1................................................. 51 

Figure 20: NOx emissions for HHDDT_S mode (56,000 lbs.). The high value for the 

1975-1976 MY bin is due to a single truck with high NOx emissions. .................... 52 

Figure 21: NOx emissions for UDDS mode (56,000 lbs.). ............................................... 53 

Figure 22: PM emissions for Idle Mode. Truck E55CRC-45, in the 1991-1993 MY bin, 

was a prodigious emitter and raised the average value for that bin substantially..... 53 

Figure 23: PM emissions for Creep mode (56,000 lbs.). One vehicle in the 1991-1993 

MY bin was a very high emitter of both PM and HC at light load........................... 54 

Figure 24: PM Emissions for the Transient mode (56,000 lbs.). Truck E55CRC-16, a high 

emitter, caused the high average in the 1977-1979 MY bin..................................... 55 

Figure 25: PM emissions for the Cruise mode (56,000 lbs.). E55CRC-16 contributed to 

the one very high MY bin average............................................................................ 55 

Figure 26: PM emissions for HHDDT_S mode (56,000 lbs.). Four MY groups show data 

from only one vehicle. .............................................................................................. 56 

Figure 27: PM emissions for UDDS mode (56,000 lbs.).................................................. 57 

Figure 28: CO emissions for Transient mode (56,000 lbs.).............................................. 57 

Figure 29: CO emissions for Cruise mode (56,000 lbs.). ................................................. 58 

Figure 30: HC emissions for Transient mode (56,000 lbs.).............................................. 59 

Figure 31: HC emissions for Cruise mode (56,000 lbs.). ................................................. 59 

Figure 32: NOx emissions for AC5080 (both laden and unladen). Gasoline-fueled 

vehicles are separated from diesel-fueled vehicles for comparison.......................... 60 

iii 
Figure 33: NOx emissions for the Lower Speed Transient mode (both laden and 

unladen)..................................................................................................................... 61

: PM emissions for the Lower Speed Transient mode (both laden and unladen).

: PM emissions for the Higher Speed Transient mode (both laden and unladen).

Figure 34: NOx emissions for the Higher Speed Transient mode (both laden and unladen).

................................................................................................................................... 62 

Figure 35: NOx emissions for the MHDT Cruise mode (both laden and unladen)........... 62 

Figure 36: NOx emissions for the HHDDT_S mode (both laden and unladen)............... 63 

Figure 37: NOx emissions for the UDDS mode (both laden and unladen)...................... 63 

Figure 38: PM emissions for the AC5080 mode (both laden and unladen)...................... 64 

Figure 39

................................................................................................................................... 65 

Figure 40

................................................................................................................................... 65 

Figure 41: PM emissions for the Cruise mode (both laden and unladen)........................ 66 

Figure 42: PM emissions for the HHDDT_S mode (both laden and unladen)................. 66 

Figure 43: PM emissions for UDDS mode (both laden and unladen). ............................. 67 

Figure 44: CO emissions for MHDTHI mode (both laden and unladen). ........................ 67 

Figure 45: CO emissions for the MHDTCR mode (both laden and unladen). ................ 68 

Figure 46: HC emissions for MHDTHI mode (both laden and unladen). ........................ 68 

Figure 47: HC emissions for MHDTCR mode (both laden and unladen). ....................... 69 

Figure 48: Example of a continuous NOx emissions plot in g/s for E55CRC-42 (56,000 

lbs.) following the HHDDT Transient Mode............................................................ 70 

Figure 49: Example of a continuous HC emissions plot in g/s for E55CRC-42 (56,000 

lbs.) following the HHDDT Transient Mode............................................................ 70 

Figure 50: Example of a continuous CO emissions plot in g/s for E55CRC-42 (56,000 

lbs.) following the HHDDT Transient Mode............................................................ 71 

Figure 51: Example of a continuous exhaust temperature reading for E55CRC-42 

(56,000 lbs.) following the Transient mode schedule............................................... 71 

Figure 52: Transient mode NOx weight effects ............................................................... 72 

Figure 53: Transient mode PM weight effect ................................................................... 73 

Figure 54: Cruise mode NOx weight effect....................................................................... 73 

Figure 55: Cruise mode PM weight effect........................................................................ 74 

Figure 56: Variation of HHDDT CO2 emissions by vehicle model year and by phase of 

the program for the UDDS (56,000 lbs.). ................................................................. 75 

Figure 57: Variation of HHDDT CO emissions by vehicle model year and by phase of the 

program for the UDDS (56,000 lbs.). ....................................................................... 76 

Figure 58: Variation of HHDDT oxides of NOx by vehicle model year and by phase of 

the program for the UDDS (56,000 lbs.). ................................................................. 77 

Figure 59: Variation of PM emissions by vehicle model year and by phase of the program

for the UDDS (56,000 lbs.)....................................................................................... 77 

Figure 60: PAH in fuels and oils....................................................................................... 81

Figure 61: Concentrations of carbonyl compounds (in ppbv) measured during the runs. 84 

Figure 62: SMPS Particle Size Distribution for E55CRC-39 Operating on an Idle Mode88 

Figure 63: SMPS Particle Size Distribution for E55CRC-39 Operating on Various Steady 

Cycles........................................................................................................................ 89 

Figure 64: PM Mass Emissions for E55CRC-39.............................................................. 89

Figure 65: Ion Composite Results for E55CRC- 39 ......................................................... 91 

iv 
Figure 66: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-39 .......... 91 

Figure 67: DMS500 Total Number of Particles and Vehicle Speed vs. Time during the 

UDDS for E55CRC-39 tested at 56,000 lbs. ............................................................ 92 

Figure 68: DMS500 Total Number of Particles and Engine Power vs. Time during the 

UDDS for E55CRC-39 tested at 56,000 lbs. ............................................................ 93 

Figure 69: DMS500 60 nm and 20 nm Particle Number vs. Time during the UDDS for 

E55CRC-39 tested at 56,000 lbs............................................................................... 93 

Figure 70: DMS500 60 nm Particle Number vs. 20 nm Particle Number during the UDDS 

for E55CRC-39 tested at 56,000 lbs. ........................................................................ 94 

Figure 71: DMS500 60 nm Particle Number vs. Total Hub Power during the UDDS for 

E55CRC-39 tested at 56,000 lbs............................................................................... 94 

Figure 72: DMS500 20 nm Particle Number vs. Total Hub Power during the UDDS for 

E55CRC-39 tested at 56,000 lbs............................................................................... 95 

Figure 73: DMS500 size distribution of particles during Idle (t = 230 s) of the UDDS for 

E55CRC-39 tested at 56,000 lbs............................................................................... 96 

Figure 74: DMS500 size distribution of particles during acceleration (t = 530 s) of the 

UDDS for E55CRC-39 tested at 56,000 lbs. ............................................................ 97 

Figure 75: DMS500 size distribution of particles during deceleration (t = 770 s) of the 

UDDS for E55CRC-39 tested at 56,000 lbs. ............................................................ 97 

Figure 76: DMS500 size distribution of particles during HHDDT_S and Vehicle Speed 

vs. Time for E55CRC-39 tested at 56,000 lbs. ......................................................... 98 

Figure 77: DMS500 size distribution of particles during Transient and Vehicle Speed vs. 

Time for E55CRC-39 tested at 56,000 lbs................................................................ 98 

Figure 78: DMS500 size distribution of particles during Cruise3 and Vehicle Speed vs. 

Time for E55CRC-39 tested at 56,000 lbs................................................................ 99 

Figure 79: SMPS Particle Size Distribution for E55CRC-40 Operating on an Idle Mode

................................................................................................................................. 100 

Figure 80: SMPS Particle Size Distribution for E55CRC-40 Operating on Various Steady 

Cycles...................................................................................................................... 101

Figure 81: PM Mass Emissions for E55CRC-40............................................................ 102

Figure 82: Ion Composite Results for E55CRC-40 ........................................................ 102 

Figure 83: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-40 ........ 103 

Figure 84: SMPS Particle Size Distribution for E55CRC-41 Operating on an Idle Mode

................................................................................................................................. 104 

Figure 85: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-41 ........ 105 

Figure 86: Total PM Mass Emissions Rate (g/hour) for E55CRC-41............................ 106 

Figure 87: SMPS Particle Size Distribution for E55CRC-41 Operating under Cruise and 

Steady Conditions ................................................................................................... 106 

Figure 88: SMPS Particle Size Distribution for E55CRC-41 Operating on Cruise and 

Steady Conditions (50% GVWR)........................................................................... 107 

Figure 89: Ion Composite Results for E55CRC-41 ........................................................ 107 

Figure 90: SMPS Single Particle Trace (82 nm) for E55CRC-41 Operating on UDDS,

Low Transient and High Transient Cycles (75%GVWR) ...................................... 108 

Figure 91: SMPS Single Particle Trace (24 nm) for E55CRC-41 Operating on Low 

Transient and High Transient Cycles (75% GVWR) ............................................. 109 

v 
Figure 92: SMPS Single Particle Trace (88 nm) for E55CRC-41 Operating on Low 

Transient and High Transient Cycles (50% GVWR) ............................................. 109 

Figure 93: DMS500 Total Number of Particles and Vehicle Speed vs. Time during 

UDDS for E55CRC-41 tested at 56,000 lbs. .......................................................... 110 

Figure 94: DMS500 60 nm and 20 nm Particle Number vs. Time for E55CRC-41 tested 

at 56,000 lbs............................................................................................................ 111 

Figure 95: DMS500 Total Number of Particles and CO vs. Time for E55CRC-41 tested at 

56,000 lbs................................................................................................................ 112 

Figure 96: DMS500 60 nm Particle Number vs. 20 nm Particle Number for E55CRC-41

tested at 56,000 lbs.................................................................................................. 112 

Figure 97: DMS500 20 nm Particle Number vs. Total Hub Power for E55CRC-41 tested 

at 56,000 lbs............................................................................................................ 113 

Figure 98: DMS500 60 nm Particle Number vs. Total Hub Power for E55CRC-41 tested 

at 56,000 lbs............................................................................................................ 113 

Figure 99: DMS500 size distribution of particles during acceleration and deceleration for 

E55CRC-41 tested at 56,000 lbs............................................................................. 114 

Figure 100: SMPS Particle Size Distribution for E55CRC-42 Operating on an Idle Mode

................................................................................................................................. 115 

Figure 101: SMPS Particle Size distribution for E55CRC-42 operating on various steady 

cycles....................................................................................................................... 115 

Figure 102: PM Mass Emissions for E55CRC-42.......................................................... 116

Figure 103: Ion Composite Results for E55CRC-42 ...................................................... 117 

Figure 104: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-42 ...... 117 

Figure 105: DMS500 Total Number of Particles and Vehicle Speed vs. Time on Transient 

mode for E55CRC-42 tested at 56,000 lbs. ............................................................ 118 

Figure 106: SMPS Particle Size Distribution for E55CRC-43 Operating on an Idle Mode

................................................................................................................................. 119 

Figure 107: SMPS Particle Size Distribution for E55CRC-43 Operating on Various 

Steady Cycles.......................................................................................................... 119 

Figure 108: PM Mass Emissions for E55CRC-43.......................................................... 120

Figure 109: Ion Composite Results for E55CRC-43 ...................................................... 121 

Figure 110: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-43 ...... 121 

Figure 111: DMS500 Total Number concentration of Particles and Vehicle Speed vs. 

Time for E55CRC-43 tested at 56,000 lbs.............................................................. 122 

Figure 112: SMPS Particle Size Distribution for E55CRC-44 Operating on an Idle Mode

................................................................................................................................. 123 

Figure 113: SMPS Particle Size Distribution for E55CRC-44 Operating on Various 

Steady Cycles.......................................................................................................... 123 

Figure 114: PM Mass Emissions for E55CRC-44.......................................................... 124

Figure 115: Ion Composite Results for E55CRC-44 ...................................................... 125 

Figure 116: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-44 ...... 125 

Figure 117: Elemental Carbon Emissions (Percentage of Total Carbon)....................... 127 

Figure 118: Inorganic Ionic Species Emissions.............................................................. 128 

Figure 119: Lubrication Oil Emissions........................................................................... 129

Figure 120: Engine Wear Emissions............................................................................... 130 

vi 
Figure 121: NOx/CO2 ratios for each run on the 25 vehicles, both transient and cruise. 

One vehicle was found to have high NOx emissions on two runs of the cruise mode

................................................................................................................................. 136 

Figure 122: NOx emissions plotted against the dispersed and time aligned power for 

vehicle E55CRC-10. Most emissions during the Cruise mode were at an off-cycle 

level. The vehicle was targeted for Reflash as a result of these data...................... 137 

Figure 123: PM/CO2 ratios for Cruise Mode operation of average value for each vehicle. 

There are two runs each for E55CRC-1 to -13, and three runs each for E55CRC-14 

to -25. ...................................................................................................................... 138 

Figure 124: PM/CO2 ratios for the Transient Mode operation of average value for each 

vehicle. There are 2 runs each for E55CRC-1 to -13, 3 runs each for E55CRC-14 to -

25. One run for E55CRC-20 was anomalous low, but no cause was evident......... 139 

Figure 125: Occurrence of criterion ratios by bin for the Laden Transient Mode 

(PM/CO2). E55CRC-16 was not included in this analysis, because it was an extreme 

outlier. ..................................................................................................................... 140 

Figure 126: Occurrence of criterion ratios by bin for the Laden Cruise mode (PM/CO2). 

E55CRC-16 was not included in this analysis because it was an extreme outliner.141 

Figure 127: Transient Mode NOx emissions before and after reflashing E55CRC-10... 153 

Figure 128: NOx emissions versus power for E55CRC-10 after reflashing. The mass rate 

of NOx emissions was reduced in many parts of the Cruise mode (compared to 

Figure 122). The highest mass rate emissions were also slightly lower than before 

the reflash................................................................................................................ 154 

Figure 129: NOx emissions on Cruise mode (56,000 lbs.) for three vehicles before reflash. 

NOx emissions and hub power were time-aligned before plotting. ........................ 158 

Figure 130: NOx emissions on the three reflash vehicles were reduced in Cruise mode 

after reflash. Test weight was 56,000 lbs................................................................ 158 

Figure 131: As-received and retest after reflash NOx data for E55CRC-26 (56,000 lbs.).

................................................................................................................................. 159 

Figure 132: As-received and retest after reflash PM data for E55CRC-26 (56,000 lbs.).

................................................................................................................................. 159 

Figure 133: PM emission for E55CRC-28 for the UDDS, Cruise and HHDDT_S Modes.

................................................................................................................................. 160 

Figure 134: PM emissions for the Transient and Creep Modes for E55CRC-28. .......... 161 

Figure 135: NOx emissions for E55CRC-28 at 56,000 lbs. on the UDDS and the Cruise 

and HHDDT_S Modes............................................................................................ 162 

Figure 136: NOx emissions for E55CRC-28 at 56,000 lbs. on the Transient and Creep 

Modes...................................................................................................................... 162 

Figure 137: As-received and reflash emissions for NOx emissions for E55CRC-31 tested 

at 56,000 lbs............................................................................................................ 164 

Figure 138: As-received and reflash emissions for PM emissions for E55CRC-31....... 164

Figure 139: shows the inability of E55CRC-57 to meet the target trace........................ 167 

vii 
LIST OF TABLES 

Table 1: Highest, lowest, and average emissions of NOx and PM for all HHDDT (56,000 

: List of Gas-phase Compounds Quantified by GC/MS Method from Canisters.

: T&M Determination Data for the HHDDT Vehicles over the Transient Mode

lbs.).............................................................................................................................. 2 

Table 2: Emissions of regulated species by MY for HHDDT tested on the UDDS (56,000 

lbs.).............................................................................................................................. 3 

Table 3: Highest, lowest, and average emissions of NOx and PM for all MHDDT tested at 

75% GVWR................................................................................................................ 3 

Table 4: The effect of changing test weight on the diesel-fueled MHDT, in terms of a 

simple average of emissions for that fleet................................................................... 4 

Table 5: Vehicles planned for recruiting in the E-55/59 program. .................................. 10 

Table 6: Federal and ARB past and present emissions standards..................................... 11 

Table 7: Vehicle Selection Matrix: NOx, PM, VMT population (as percentages of total).

................................................................................................................................... 11 

Table 8: Basic Information on the 78 trucks actually recruited....................................... 12 

Table 9: Sampling system description and media type..................................................... 21 

Table 10: Test Schedule Summary. AC5080 performance depends on truck power to 

weight ratio. .............................................................................................................. 24 

Table 11: AC5080 Methodology. ..................................................................................... 26 

Table 12: Test Vehicle Details.......................................................................................... 44 

Table 13: List of Target Analytes in the Particulate and Semi-Volatile Fractions........... 78 

Table 14

................................................................................................................................... 82 

Table 15: List of Target Analytes in the Gas-Phase Carbonyl Compound Fraction ........ 83 

Table 16: Nitrosoamines Targeted for Analysis in the Vehicle Exhaust.......................... 84 

Table 17: List of Heavy Hydrocarbons for Tenax Samples ............................................. 85 

Table 18: Damaged Tenax Samples. ............................................................................... 86 

Table 19: Emissions level criteria used to declare a truck to be a high NOx emitter...... 134 

Table 20: Definition of criterion ratios by bin for the Laden Transient Mode: see Figure 

125........................................................................................................................... 140 

Table 21: Definition of criterion by bin for the Laden Cruise Mode: See Figure 126. .. 141 

Table 22: T&M Determination Data for the HHDDT Vehicles over the Cruise Mode . 143 

Table 23

................................................................................................................................. 147 

Table 24: E55CRC-3: UDDS (g/mile)............................................................................ 151 

Table 25: E55CRC-3 retest UDDS (g/mile) ................................................................... 151 

Table 26: E55CRC-3: 1828-1 Idle, 1828-2 Creep, 1828-3 Transient, 1828-4 Cruise. 

(g/mile, except idle in g/cycle)................................................................................ 151 

Table 27: E55CRC-3: 1829-1 Idle, 1829-2 Creep, 1829-3 Transient, 1829-4 Cruise. 

(g/mile, except idle in g/cycle)................................................................................ 152 

Table 28: E55CRC-3 retest: 1939-1 Idle, 1939-5 Creep, 1939-3 Transient, 1939-4 Cruise 

(g/mile, except idle in g/cycle)................................................................................ 152 

Table 29: E55CRC-3 retest: 1942-1 Idle, 1942-5 Creep, 1942-3 Transient, 1942-4 Cruise. 

(g/mile, except idle in g/cycle)................................................................................ 152 

viii 
Table 30: E55CRC-10 baseline emissions and “reflash” emissions. T&M runs are 

denoted in bold. NOx

1

 and NOx

2

 show values from two similar analyzers in parallel. 

It should be noted that Idle and Creep Modes often return highly variable emissions 

due to changing auxiliary loads on the vehicle....................................................... 154 

Table 31: E55CRC-16 Emissions before and after T&M procedures. T&M 1 in bold 

represents testing with a new fuel injection pump; T&M 2 in bold italics represents 

testing with a new pump and EGR totally disabled................................................ 155 

Table 32: E55CRC-21 emissions T&M results in bold.................................................. 157 

Table 33: Sequence of testing for E55CRC-31............................................................... 163 

Table 34: E55CRC-45 as received, after first repair (R), and after second repair (RR).166 

ix 
LIST OF APPENDICES 

Appendix A: Photograph and Description of Each Test Vehicle 

Appendix B: WVU Test Vehicle Information Sheets 

Appendix C: Description of the WVU Transportable Heavy Duty Vehicle Emissions 

Testing Laboratory (Translab) 

Appendix D: WVU Vehicle Inspection Sheets 

Appendix E: WVU Tampering and Malmaintenance (T&M) Issues Sheets 

Appendix F: Engine Control Unit Downloads 

Appendix G: DRI Methods 

Appendix H: Graphical Representation of Each Test Schedule 

Appendix I: SMPS and CPC reduction program 

Appendix J: Table of Test Runs 

Appendix K: WVU Short Reports for Each Test 

Appendix L: WVU Summary Data Tables 

Appendix M: Graphical Representation of Data Found in the WVU Short Reports 

Appendix N: Chemical Speciation Results 

Appendix O: List of Target Chemical Species Analyzed 

Appendix P: Quality Assurance and Control 

x 
EXECUTIVE SUMMARY 

Program E-55/59 had the objective of acquiring regulated emissions measurements (for 

the whole test fleet) and non-regulated emissions measurements (on a subset of the test 

fleet) from in-use trucks in southern California. The project was conducted in four Phases 

(denoted 1, 1.5, 2 and 3). The Phase 1 test fleet consisted of 25 Heavy Heavy-Duty Diesel 

Trucks (HHDDT), selected to match a model year (MY) distribution developed by the 

sponsors and to reflect engines in common use in California. In Phase 1.5 an additional 

twelve HHDDT were studied, with a thirteenth truck tested on idle alone. The Phase 2 

test fleet consisted of ten HHDDT and nine Medium Heavy-Duty Trucks (MHDT), 

which included seven diesel - fueled MHDT (MHDDT) and two gasoline-fueled MHDT 

(MHDGT). Phase 3 gathered data from nine HHDDT, eight MHDDT, and two MHDGT. 

The Phase 2 and 3 data were valuable in adding post-2002 MY (2.5 g/bhp-hr NOx 

standard) HHDDT to the E-55/59 program. 

Test cycles for all HHDDT were the Urban Dynamometer Driving Schedule (UDDS) and 

the HHDDT schedule, and some trucks were tested using the AC50/80. The HHDDT 

Schedule consisted of four modes, namely Idle, Creep, Transient and Cruise, and a high 

speed” cruise mode (HHDDT_S) was added for phase 1.5, 2 and 3. The MHDT were all 

tested using a Lower Speed Transient Mode (MHDTLO), a Higher Speed Transient 

Mode (MHDTHI) and a Cruise Mode (MHDTCR) of a recently developed California Air 

Resources Board (CARB) MHDT Schedule, and three MHDT were tested using the 

High-speed HHDDT_S mode of the HHDDT Schedule as well.. All HHDDT were tested 

at 56,000 lbs weight, with subsets tested at 30,000 lbs. and 66,000 lbs. as well. MHDT 

were tested at 50% and 75% of Gross Vehicle Weight Rating (GVWR). The first thirteen 

HHDDT in Phase 1 were subjected to sampling for non-regulated emissions, and the 

samples from the first three of these trucks were analyzed. Non-regulated species were 

measured from five HHDDT and one MHDDT in the Phase 2 test fleet. The HHDDT 

emissions were characterized using the West Virginia University (WVU) Transportable 

Heavy-Duty Emissions Testing Laboratory (TransLab). 

Emissions were diluted in an 18 inch diameter tunnel, with flow controlled by a critical 

flow venturi. Gaseous emissions were measured with research grade analyzers, and total 

PM was measured from dilute exhaust using 70mm filters. PM data were acquired in 

Phases 1.5, 2 and 3 using both conventional filters and a Tapered Element Oscillating 

Microbalance (TEOM). The TEOM correlated well with the filters in each phase. Two 

chemiluminescent analyzers were used to assure quality of NOx measurements. 

The regulated emissions data for HHDDT (56,000 lbs. test weight) were compared 

between phases. Carbon dioxide data agreed well between phases, suggesting that vehicle 

loading was consistent from phase to phase. Data for CO, NOx and PM were compared 

between phases. There were too few trucks, distributed over a wide range of model years, 

to reach emissions conclusions based on data from a single phase. For example, the Phase 

2 fleet included only one truck in the 1991-1993 model year range, and its NOx emissions 

were substantially lower than the NOx emissions from the five trucks in the 1991-1993 

1 
model year range tested in Phases 1 and 1.5. The value of using the combined emissions 

data from all phases to reach conclusions on age or model year effects was evident. 

Table 1 provides a summary of NOx and PM data averages and ranges for the HHDDT 

fleet in all Phases, and for all MY, by test cycle or mode, at 56,000 lbs. test weight. 

Oxides of nitrogen (NOx) varied fourfold on the Transient Mode, but sevenfold on the 

Cruise Mode, reflecting both off-cycle behavior and recent stringent NOx standards. The 

high-speed HHDDT_S mode also showed a sevenfold range of NOx. Average values for 

NOx, in distance specific units, declined with respect to average cycle or mode speed. PM 

variation (geometrically) was greater than NOx variation, with trucks producing 

emissions at the laboratory lower detection limit on all modes, but with the maximum 

values between four and eighteen times the average value for each mode or cycle. 

Table 1: Highest, lowest, and average emissions of NOx and PM for all HHDDT 

(56,000 lbs.). 

Idle 

HHDDT 

Creep 

HHDDT 

Transient 

HHDDT 

Cruise 

HHDDT 

HHDDT_S UDDS 

(g/min) (g/mile) (g/mile) (g/mile) (g/mile) (g/mile) 

Highest NOx 4.43 162.94 60.22 49.43 55.75 53.35 

Average NOx 1.10 56.68 23.50 18.07 17.94 21.67 

Lowest NOx 0.00 7.77 13.65 7.03 8.05 11.98 

Highest PM 0.71 67.77 17.14 17.14 3.83 12.99 

Average PM 0.04 5.25 2.65 1.08 0.85 1.78 

Lowest PM 0.00 0.00 0.00 0.00 0.00 0.00 

Emissions were influenced by MY, as shown in Table 2, for the UDDS. Fuel consumed 

(by carbon balance from CO2) was highest for the oldest MY bin. For the remaining 

vehicles the 1999 and later MY vehicles used more fuel than the pre-1999 MY vehicles. 

2003 and later MY HHDDT used 16% more fuel on the UDDS than 1975-1998 MY 

trucks, on average. HHDDT for the three oldest MY bins produced about 27 g/mile NOx 

on the UDDS. NOx was lower for intermediate MY trucks, rising back to about 27 g/mile 

in 1998 MY trucks. For 1999-2002 MY, NOx was reduced to 19.22 g/mile, and, for 2003 

and later MY, NOx was reduced to 13.74 g/mile on the UDDS. There was a strong trend 

showing that PM was reduced for the HHDDT on the UDDS as MY advanced, with the 

1986 and older MY fleet at 2 to 5 g/mile, and 2003 and later MY trucks at 0.50 g/mile. 

The trend for CO followed the PM trend. Fleet-averaged HC emissions on the UDDS 

showed a substantial reduction in the mid ‘90s. 

2 
Table 2: Emissions of regulated species by MY for HHDDT tested on the UDDS 

(56,000 lbs.). 

CO 

g/mile 

CO2 

g/mile 

NOx 

g/mile 

HC 

g/mile 

PM 

g/mile 

Pre-1975 Average 

Std Dev. 

12.21 

1.82 

2766 

21 

28.46 

3.53 

6.11 

1.94 

3.47 

0.55 

1975-1979 Average 

Std Dev. 

33.53 

29.19 

2298 

206 

26.41 

10.98 

1.98 

0.47 

4.94 

5.33 

1980-1983 Average 

Std Dev. 

21.31 

11.60 

2225 

243 

27.40 

2.99 

2.11 

0.06 

2.18 

1.11 

1984-1986 Average 

Std Dev. 

16.40 

8.36 

2174 

80 

18.67 

8.71 

2.44 

1.37 

2.30 

1.03 

1987-1990 Average 

Std Dev. 

13.50 

6.11 

2111 

183 

19.42 

3.67 

1.63 

1.82 

1.86 

0.86 

1991-1993 Average 

Std Dev. 

8.45 

4.90 

2071 

71 

18.00 

2.21 

2.64 

3.67 

1.10 

0.50 

1994-1997 Average 

Std Dev. 

7.59 

4.25 

2142 

218 

23.77 

6.23 

1.24 

1.85 

0.76 

0.56 

1998 Average 

Std Dev. 

7.05 

2.36 

2206 

100 

26.87 

12.36 

0.69 

0.48 

0.75 

0.22 

1999-2002 Average 

Std Dev. 

9.89 

12.74 

2419 

314 

19.22 

5.54 

0.88 

0.74 

1.04 

1.30 

2003+ Average 

Std Dev. 

2.33 

2.44 

2529 

254 

13.74 

1.36 

0.54 

0.24 

0.50 

0.47 

Table 3 presents an overview of NOx and PM emissions for the MHDDT. NOx emissions 

from MHDDT varied less than for the HHDDT fleet. For laden operation on the all 

cycles and modes, the highest NOx emitter was about twice the level of the lowest 

emitter. PM variation was more substantial for the MHDDT; the highest PM mass 

emissions were four or five times the lowest emissions. MHDDT showed little change in 

NOx between tests at laden and unladen weight, as shown in Table 4. The increase of 

50% in test weight produced an average NOx increase of only 11% on the UDDS, and 

16% on the MHDTLO. There was virtually no weight effect on NOx emissions for the 

MHDTCR for the MHDDT. The mode with the highest weight influence on PM was the 

MHDTLO (40% increase). The mode with the lowest weight influence on PM was the 

MHDTCR (7% increase). 

Table 3: Highest, lowest, and average emissions of NOx and PM for all MHDDT 

tested at 75% GVWR. 

MHDT AC5080 MHDTCR MHDTHI MHDTLO UDDS 

(g/mile) (g/mile) (g/mile) (g/mile) (g/mile) 

Highest NOx 16.50 14.03 20.87 33.05 18.82 

Average NOx 9.81 10.48 12.95 20.20 12.71 

Lowest NOx 6.49 8.74 8.85 12.20 8.36 

Highest PM 2.52 1.72 2.95 4.38 4.13 

Average PM 0.79 0.71 0.94 1.48 1.10 

Lowest PM 0.16 0.19 0.20 0.25 0.19 

3 
Table 4: The effect of changing test weight on the diesel-fueled MHDT, in terms of a 

simple average of emissions for that fleet. 

MHDT AC5080 MHDTCR MHDTHI MHDTLO UDDS 

(g/mile) (g/mile) (g/mile) (g/mile) (g/mile) 

Average Laden NOx 9.81 10.48 12.95 20.20 12.71 

Average Unladen NOx 8.85 10.13 11.20 17.40 11.44 

Average Laden PM 0.79 0.71 0.94 1.48 1.10 

Average Unladen PM 0.62 0.66 0.72 1.06 0.82 

A Tampering and Malmaintenance (T&M) program was initiated in Phase 1 to identify 

the incidence of high emitters and to determine the effect of repair on high emitters. 

Vehicles were selected based either on an inspection, or on the measurement of PM and 

NOx emissions above thresholds that took into account MY emissions standards. A 1985 

MY truck showed reduction of PM and increase in NOx after a mechanical timing fault 

was repaired. A 1979 truck was a prodigious PM emitter, and was found to defy effective 

repair. A 1990 truck with a plugged air filter showed 27% PM reduction on the UDDS 

with a new air filter. A 1993 truck with high HC and PM was repaired twice but 

emissions remained high. A defective temperature sensor in one MHDT caused emissions 

effects, but it was not subjected to repair. A 1998 MY HHDDT with high NOx emissions 

was reflashed in Phase 1, and NOx was reduced during cruising behavior. Reflash of three 

additional HHDDT in Phase 1.5 showed NOx reductions of 13.3%, 21.5% and 30.7% on 

the Cruise Mode of the HHDDT schedule. One of these vehicles was also repaired by 

replacement of a manifold air pressure (MAP) sensor, which also affected NOx 

emissions. 

Size distributions of PM were characterized from six trucks that were selected for nonregulated emissions measurement. These data were acquired using a Scanning Mobility 

Particle Sizer (SMPS), as well as a Differential Mobility Spectrometer (DMS500), which 

was a newly released instrument. A raw exhaust slipstream was diluted by a factor of 

thirty in a mini-dilution tunnel, and this dilute stream was sampled by the SMPS. The 

DMS used the main dilution tunnel of the WVU TransLab, which had a fixed flow and a 

varying dilution ratio. The SMPS detected a bimodal distribution with a nuclei mode for 

Idle operation of one 2004 MY truck (E55CRC-40), and the DMS 500 detected both the 

nuclei mode and accumulation mode during deceleration on this truck. The nuclei mode 

was not evident under load for E55CRC-40. The other 2004 MY truck had only one 

mode, with a very low particle count on Idle. A 1989 MY truck had a bimodal Idle 

distribution, but the remaining HHDDT were unimodal. Comprehensive data were 

acquired for steady operation using the SMPS on all trucks, and the DMS500 acquired 

transient distributions for four of the trucks. 

Sampling for chemical speciation was performed on thirteen HHDDT in Phase 1 and on 

five HHDDT and one MHDDT in Phase 2. In Phase 1, only three of the thirteen trucks 

had the samples analyzed, and the remaining samples were archived. The exhaust from 

the TransLab tunnel was fed to a residence time chamber of the Desert Research Institute 

(DRI). Data were acquired for methane and volatile organic compounds using a canister 

and a field gas chromatograph. Semi-volatile organic compounds were captured in 

4 
PUF/XAD media and PM soluble fractions were captured on Teflon-Impregnated Glass 

Fiber Filters (TIGF) filters, and these were extracted and analyzed at the DRI laboratory. 

Carbonyls were captured using DNPH cartridges, and nitrosamines were captured in 

Thermosorb cartridges. Ions and Elemental/Organic carbon (EC/OC) split were 

determined from quartz filters. Results from the speciation data are legion, and examples 

include the fact that the EC/OC split differed substantially on Idle between the two 2004 

MY trucks equipped with EGR, and that the ion and metal analyses varied widely 

between trucks. The total carbon emissions from cruise mode were found to be the 

highest, while the total PM mass emissions rates were the highest from the transient 

mode. All pre-1999 vehicles, which were subjected to speciation analysis, were found to 

emit higher levels of engine wear elements, such as iron, than the newer vehicles. 

Likewise, oil control, as demonstrated by the lubricating oil-based ash components, was 

better in post-1999 vehicles. 

5 
NOMENCLATURE 

CA California 

CARB California Air Resources Board 

CFR Code of Federal Regulations 

CO Carbon Monoxide 

CO2 Carbon Dioxide 

CRC Coordinating Research Council 

CSHVR City Suburban Heavy Vehicle Route 

CTA California Trucking Association 

DAS Data Acquisition System 

DRI Desert Research Institute 

ECU Engine Control Unit 

EMFAC Emissions Inventory Model employed by CARB 

GVWR Gross Vehicle Weight Rating 

HC Hydrocarbons 

HEPA High Efficiency Particulate Air 

HHDDT Heavy Heavy-Duty Diesel Truck 

HHDDT_S HHDDT Short (referring to a shortened high-speed cruise mode) 

MEMS Mobile Emissions Measurement System 

mg Milligrams 

MHDDT Medium Heavy-Duty Diesel Truck 

MHDGT Medium Heavy-Duty Gasoline Truck 

MHDT Medium Heavy-Duty Truck 

MHDTCR MHDT Cruise Mode 

MHDTHI MHDT High-speed Transient Mode 

MHDTLO MHDT Low Speed Transient Mode 

MY Model Year 

N2O Nitrogen Dioxide 

NIST National Institute of Standards and Technology 

NOX Oxides of Nitrogen 

PA Power Absorber 

PM Particulate Matter 

PSVOC Particulate/Semi-Volatile Organic Compound 

QA/QC Quality Assurance & Quality Control 

RH Relative Humidity 

SOP Standard Operating Procedures 

T&M Tampering and Malmaintenance 

TEOM Tapered Element Oscillating Microbalance 

TRANS3 HHDDT Transient 

Translab Transportable Heavy Duty Vehicle Emissions Testing Laboratory 

UDDS Urban Dynamometer Driving Schedule 

USDOE United States Department Of Energy 

VMT Vehicle Miles Traveled 

VOC Volatile Organic Compounds 

WVU West Virginia University 

6 
INTRODUCTION AND OBJECTIVES 

Heavy-duty diesel vehicles are known to be substantial contributors to the inventory of 

oxides of nitrogen (NOX) and particulate matter (PM), but the quantification of their real 

world emissions may be imprecise. As a result, emissions inventory predictions may err. 

To remedy this uncertainty, Program E-55/59 was initiated. This program, consisting of 

Phases 1, 1.5, 2, and Phase 3, was managed by the Coordinating Research Council 

(CRC), and supported by the following sponsors: 

Coordinating Research Council, Inc. 

California Air Resources Board 

United States Environmental Protection Agency 

United States Department of Energy Office of FreedomCar & Vehicle Technologies 

through the National Renewable Energy Laboratory 

South Coast Air Quality Management District 

Engine Manufacturers Association 

The primary objective of the E-55/59 research program was to quantify regulated and 

certain unregulated gaseous and PM emissions for heavy-duty (primarily diesel) vehicles 

in the South Coast Air Basin to support emissions inventory development. Another 

objective of the E-55/59 program was to quantify the influence of T&M on heavy-duty 

vehicle emissions. WVU and DRI also teamed to address the measurement of emissions 

in a comprehensive effort that carefully considered a representative fleet and 

representative vehicle activity. The overall E-55/59 research program involved both the 

medium and the heavy-duty chassis dynamometer operated together with a dilution and 

sampling system to address both regulated and unregulated species. 

WVU characterized exhaust emissions from a total of 25 Heavy Heavy-Duty Diesel 

Trucks (HHDDT) in California in Phase 1 of the E-55/59 study. A T&M study was also 

developed in Phase 1. The first three vehicles were so-called “overlap” vehicles and 

were evaluated both under the USDOE “Gasoline/Diesel PM Split Study” and the E55/59 study. The overlap vehicles were sampled for both regulated and unregulated 

emissions and the unregulated emissions samples were analyzed. The next ten vehicles in 

Phase 1 underwent testing for regulated emissions but the extent of sampling for 

chemical characterization was reduced and these samples were archived for possible 

chemical analysis at a later stage. The remaining twelve vehicles in Phase 1 were tested 

only for regulated emissions and the PM10 fraction. 

Phase 1 of the research program covered only heavy heavy-duty (gross vehicle weight 

rating greater than 33,000 lbs.) vehicles. Test cycles included the UDDS, and four modes 

of the HHDDT schedule developed for the E-55/59 program and the AC5080 cycle. 

Phase 1.5 of the program had the objective of acquiring regulated emissions 

measurements from twelve in-use trucks in southern California, and supporting a thirdparty characterization of certain non-regulated species from five vehicles in the Phase 1.5 

7 
test fleet. Processing of these third-party data is not addressed in this report. In addition, 

three vehicles were re-flashed with a post consent decree engine map, and re-tested. One 

of the re-flash vehicles was also repaired and re-tested. A thirteenth vehicle was added to 

the Phase 1.5 study when difficulties were encountered in testing a new 2004 model year 

(MY) truck with intelligent traction control on the chassis dynamometer. The thirteenth 

vehicle was also a 2004 MY truck selected to satisfy the requirements for MY 

distribution of the test plan for Phase 1.5. A high speed mode was added to the HHDDT 

schedule in Phase 1.5. 

Phase 2 had the objective of acquiring regulated emissions measurements from nineteen 

in-use trucks in southern California. Ten were HHDDT, seven were Medium Heavy-Duty 

Diesel Trucks (MHDDT) and two were Medium Heavy-Duty Gasoline Trucks 

(MHDGT). The Phase 2 effort supported a DRI characterization of non-regulated species 

from five HHDDT and one MHDDT (total of 6) in the Phase 2 test fleet. Non-regulated 

exhaust characterization included speciation of both particulate matter (PM) and volatile 

organic compounds (VOC), and determination of particle size distribution. For the 

MHDDT and MHDGT, the AC5080 schedule was combined with a three mode Medium 

Heavy-Duty Truck (MHDT) schedule consisting of a low speed transient, a high-speed 

transient, and a cruise cycle. A twentieth vehicle was added to the study when 

difficulties were encountered in testing a 2002 MY truck on the WVU medium-duty 

chassis dynamometer. 

The final phase, Phase 3, had the objective of acquiring both regulated and unregulated 

species from a selected fleet of California trucks. Nine trucks were HHDDT, eight were 

MHDDT, and two were MHDGT. For the HHDDT, test cycles were the UDDS and the 

HHDDT schedule. For the MHDT, the UDDS and MHDDT schedule were used. 

The overall CRC E-55/59 program was planned to include sixty three HHDDT, 

seventeen MHDDT, and four MHDGT for measurement of regulated emissions. 

Regulated emissions were collected from all vehicles. In addition, non-regulated 

emissions were collected and analyzed on eight HHDDT and one MHDDT. 

8 
VEHICLE PROCUREMENT 

Table 5 shows the combined truck recruiting objectives for all phases. This table lists the 

vehicles planned for each phase of the E-55/59 program broken down by vehicle MY, 

weight, fuel, and whether vehicles were to be subjected to non-regulated emissions 

analysis. 

These vehicles complied with a MY distribution determined by the Air Resources Board 

and Coordinating Research Council. HHDDT were considered to be vehicles with a 

gross vehicle weight rating (GVWR) over 33,000 lbs., as well as any “full size” single 

axle tractors, since these typically have a Gross Combination Weight of 52,000 lbs. to 

80,000 lbs. The term “full size” was intended to exclude any medium heavy-duty “hot 

shot” combinations that have become more common on the highways over the last 

decade. 

The rationale for basing recruitment on MY is discussed below. The most important 

variable that influences emissions was believed to be the engine certification standard. 

This is reflected in the engine MY and the vehicle MY corresponds closely to the engine 

MY. The vehicle MY may not reflect the appropriate standard in the unusual case of a 

vehicle re-power when an engine of a newer standard may be installed. Rebuilds will 

normally return the engine to its original condition, whereas a re-power will usually 

employ a newer technology engine. The engine MY influences the level of emissions for 

certification, as shown in Table 6, which presents the Federal and California standards for 

such engines. At time of manufacture, vehicle MY is either the same as engine MY, or 

one year later. 

The California Air Resources Board (CARB) used the EMFAC emissions inventory 

program to generate data for vehicle population, VMT, NOX production and PM 

production. These CARB data (each weighted 25%) were combined to arrive at a test 

vehicle distribution by MY. 

Table 7 shows the VMT, NOX, PM and population distributions. WVU was instructed by 

ARB and CRC to employ these distributions in the execution of E-55/59. The Table 7 

matrix was processed further to yield an integer number in each MY group. The target 

MY distribution was altered in Phase 2 and 3 to allow the inclusion of 2002-2004 MY 

trucks. 

9 
Table 5: Vehicles planned for recruiting in the E-55/59 program. 

Phase 1 Phase 1.5 Phase 2 Phase 3 

Subttl 

Reg 

Species 

Qty 

Chemical 

analysis 

qty1 

Post-Oct ‘02 

2.5g/bhp-hr 

NOx2 

Reg Species 

Qty 

Chemical 

analysis 

qty1 

Post-Oct ‘02 

2.5g/bhp-hr 

NOx2 

Reg 

Species 

Qty 

Chemical 

analysis 

qty1 

Post-Oct 

‘02 

2.5g/bhp-hr 

NOx2 

2004 

4.0g/bhphr Nox 

Reg 

Species 

Qty 

HHDDT 

pre-1975 1 0 0 0 0 0 0 0 0 1 2 

HHDDT 1975-76 1 0 0 0 0 0 0 0 0 1 2 

HHDDT 1977-79 1 0 0 0 0 0 0 0 0 0 1 

HHDDT 1980-83 2 0 0 0 0 0 0 0 0 1 3 

HHDDT 1984-86 3 0 0 0 0 0 1 0 0 0 4 

HHDDT 

Pre-1987 

(Phase 

1.5 only) 0 0 0 1 0 0 0 0 0 0 1 

HHDDT 1987-90 4 0 0 0 0 0 2 1 0 3 10 

1987-92 

(Phase 0 0 0 1 0 0 0 0 0 0 1 

HHDDT 1.5 only) 

HHDDT 1991-93 3 0 0 0 0 1 0 0 0 4 

HHDDT 1994-97 5 0 0 0 0 2 1 0 2 10 

HHDDT 1998 2 0 0 3 0 0 1 0 0 0 6 

HHDDT 99-02 3 0 0 8 0 0 1 1 0 0 13 

HHDDT 03+ 0 0 0 0 0 0 2 2 1 1 6 

HHDDT Subttl 25 0 0 13 0 0 10 5 1 0 9 63 

MHDDT pre-1975 0 0 0 0 0 0 0 0 0 0 1 1 

MHDDT 1975-76 0 0 0 0 0 0 0 0 0 0 0 0 

MHDDT 1977-79 0 0 0 0 0 0 0 0 0 0 0 0 

MHDDT 80-83 0 0 0 0 0 0 1 0 0 0 0 1 

MHDDT 84-86 0 0 0 0 0 0 0 0 0 0 1 1 

MHDDT 87-90 0 0 0 0 0 0 1 0 0 0 1 2 

MHDDT 

1988-

1990 0 0 0 0 0 0 0 0 0 0 0 0 

91-97 0 

(Phase 3 0 0 0 0 0 0 0 0 0 0 0 

MHDDT Only) 

MHDDT 91-93 0 0 0 0 0 0 1 0 0 0 1 2 

MHDDT 94-97 0 0 0 0 0 0 1 0 0 0 2 3 

MHDDT 98 0 0 0 0 0 0 1 1 0 0 1 3 

99+ 3 

(Phase 2 0 0 0 0 0 0 2 0 1 0 0 

MHDDT Only) 

99-02 1 

MHDDT 

(Phase 3 

Only) 

0 0 0 0 0 0 0 0 0 0 1 

MHDDT 00+ 0 0 0 0 0 0 0 0 0 0 0 0 

MHDDT Subttl 0 0 0 0 0 0 7 1 1 0 8 17 

MHDGT pre-1975 NA NA NA NA NA NA 0 0 0 0 0 0 

MHDGT 1975-76 NA NA NA NA NA NA 0 0 0 0 0 0 

MHDGT 1977-79 NA NA NA NA NA NA 0 0 0 0 0 0 

MHDGT 80-83 NA NA NA NA NA NA 0 0 0 0 0 0 

MHDGT 84-86 NA NA NA NA NA NA 1 0 0 0 0 1 

MHDGT 87-90 NA NA NA NA NA NA 0 0 0 0 0 0 

MHDGT 1988-

1990 NA NA NA NA NA NA 0 0 0 0 1 1 

91-97 

MHDGT (Phase 3 NA NA NA NA NA NA 0 0 0 0 1 1 

Only) 

MHDGT 00+ NA NA NA NA NA NA 1 0 0 0 0 1 

MHDGT Subttl 0 0 0 0 0 0 2 0 0 0 2 4 

Overall 

Total 25 0 0 13 0 0 19 6 2 0 19 84 

10
Table 6: Federal and ARB past and present emissions standards. 

FEDERAL HEAVY-DUTY TRUCK STANDARDS CALIFORNIA HEAVY-DUTY TRUCK 

STANDARDS 

MODEL 

YEAR 

HC1 CO NOX PM HC+NOX MODEL 

YEAR 

HC1 CO NOX PM HC+NOX 

g/bhp-hr g/bhp-hr 

1974-78 

1979-83 

1984-87 

1988-90 

1991-93 

1994-97 

1998-02 

2003+ 

--- 

1.5 

1.3 

1.3 

1.3 

1.3 

1.3 

0.52 

40.0 

25.0 

15.5 

15.5 

15.5 

15.5 

15.5 

15.5 

--- 

--- 

10.7 

10.7 

5.0 

5.0 

4.0 

2.0 

--- 

--- 

--- 

0.60 

0.25 

0.10 

0.10 

0.10 

16.0 

10.0 

--- 

--- 

--- 

--- 

--- 

--- 

1975-76 

1977-79 

1980-83 

1984-86 

1987-90 

1991-93 

1994-97 

1998-02 

2003+ 

--- 

1.0 

1.0 

1.3 

1.3 

1.3 

1.3 

1.3 

0.52

30.0 

25.0 

25.0 

15.5 

15.5 

15.5 

15.5 

15.5 

 15.5 

--- 

7.5 

5.1 

6.0 

5.0 

5.0 

4.0 

2.0 

--- 

--- 

--- 

--- 

--- 

0.60 

0.25 

0.10 

0.10 

0.10 

10.0 

6.0 

--- 

--- 

--- 

--- 

--- 

--- 

--- 

1 Note: the HC standards shown are total hydrocarbons except for model year 2003+ which is NMHC. 2 Assumes 2.5 g/bhp-hr (NOX+NMHC) with a 0.5 g/bhp-hr NMHC cap effective October 2002. 

Table 7: Vehicle Selection Matrix: NOx, PM, VMT population (as percentages of 

total).

 Pop VMT NOX PM Average 

pre-1975 5.2 1.2 2.0 3.4 2.95 

1975-76 1.5 0.5 0.8 1.3 1.03 

1977-79 4.8 1.9 3.1 5.3 3.78 

1980-83 7.8 3.9 6.1 10.7 7.13 

1984-86 12 7.7 9.1 13.7 10.63 

1987-90 23.7 19.8 18.5 21.8 20.95 

1991-93 13.3 14.2 13.1 14.1 13.68 

1994-97 16.6 22.9 24.4 18.1 20.50 

1998 4.0 7.0 8.5 4.2 5.93 

1999-01 11.1 20.9 14.5 7.4 13.48 

100 100 100.1 100 100.03 

The California Trucking Association (CTA), through a survey, obtained information for 

use in Phase 1 on the distribution of engine types by MY, and so by certification standard 

(MY group). The CTA matrix was then reviewed to identify preferred engine 

manufacturers in each MY group. The matrix did contain errors due to imprecise survey 

replies (with similar engine models having multiple names, truck models substituted for 

engines, some medium duty engines in the matrix and engines assigned to the wrong 

manufacturer) and an effort was made to compensate for these errors. The test matrix 

was selected considering engine count and in some cases the need to gather some engine 

models together or represent a variety of engines. 

Many of the vehicles recruited in Phase 1 were procured by CTA. To identify potential 

11 
study participants, CTA first contacted the survey respondents that had the desired MY 

trucks and engines in their fleets and indicated on the survey that they would be willing to 

participate in the study. CTA also sent out several faxes soliciting participation and 

phoned the entire membership in the Los Angeles/Orange/San Bernardino/Riverside 

areas to complete the study. Since not all the members had participated in the survey, the 

engine makeup of many fleets was unknown and the CTA staff were "cold calling" to 

find the appropriate study engines. One truck, E55CRC-21, was procured from a rental 

company by CTA. 

A few trucks in Phase 1 were procured directly by WVU. In all subsequent phases of the 

study, WVU recruited all of the test vehicles. These vehicles were procured from a 

variety of sources including owner-operators, truck fleets, and rental companies. Many 

of the trucks in Phase 1.5 and following were procured from used truck dealerships. 

Table 8 lists the vehicles which were actually recruited under this program. The vehicles 

are broken down by their reference number, weight class and fuel, vehicle MY, vehicle 

manufacturer, horsepower, and engine manufacturer. Trucks were designated as 

E55CRC-XX according to the order of recruitment. Details are provided in Table 8 for 

78 trucks, but three of the trucks recruited were not characterized fully for emissions. 

Truck E55CRC-37 was a 2004 Volvo HHDDT with traction control and the truck could 

not be operated on the chassis dynamometer. Idle emissions only were obtained for this 

truck. Truck E55CRC-67 was a 1975 Ford HHDDT procured with assistance from the 

Gateway Cities Program. It was not functional beyond brief periods of idle. Truck 

E55CRC-52 was a 2002 Isuzu MHDDT. Subsequent to testing, a detailed quality 

assurance review of the data found that coastdown parameters had been incorrect and, 

therefore, that the dynamometer loading was significantly in error. The vehicle had been 

sold and the new owner would not allow it to be returned for a retest. A substitute 

vehicle was found. 

Table 8: Basic Information on the 78 trucks actually recruited. 

E55CRC-

(truck) 

M=MHDT 

H=HHDT 

Vehicle 

model 

year 

Vehicle 

Manufacturer 

Engine Model Engine 

Power 

(hp) 

Engine 

Manufacturer 

E55CRC-1 H 1994 Freightliner Series 60 470 Detroit 

E55CRC-2 H 1995 Freightliner 3406B 375 Caterpillar 

E55CRC-3 H 1985 International NTCC-300 300 Cummins 

E55CRC-4 H 2000 International C-10 270 Caterpillar 

E55CRC-5 H 2000 Freightliner N14-435E1 435 Cummins 

E55CRC-6 H 1995 Freightliner M11-370 370 Cummins 

E55CRC-7 H 1990 Peterbilt Series 60 450 Detroit 

E55CRC-8 H 1996 Kenworth M11-300 370 Cummins 

E55CRC-9 H 1998 Peterbilt C12 410 Caterpillar 

E55CRC-10 H 1998 Sterling Series 60 470 Detroit 

E55CRC-11 H 2000 Freightliner ISM-11 330 Cummins 

E55CRC-12 H 1986 International 300 300 Cummins 

E55CRC-13 H 1978 Freightliner 350 350 Cummins 

E55CRC-14 H 1986 Freightliner LTA10 270 Cummins 

12 
E55CRC-

(truck) 

M=MHDT 

H=HHDT 

Vehicle 

model 

year 

Vehicle 

Manufacturer 

Engine Model Engine 

Power 

(hp) 

Engine 

Manufacturer 

E55CRC-15 H 1973 Kenworth NTC-350 350 Cummins 

E55CRC-16 H 1979 White 3208 200 Caterpillar 

E55CRC-17 H 1993 Freightliner L-10 330 Cummins 

E55CRC-18 H 1991 Ford L-10 300 Cummins 

E55CRC-19 H 1987 International L-10 300 Cummins 

E55CRC-20 H 1992 Peterbilt Series 60 450 Detroit 

E55CRC-21 H 1990 Freightliner 3406B 400 Caterpillar 

E55CRC-22 H 1993 Ford L10-280 280 Cummins 

E55CRC-23 H 1983 Peterbilt Plate Not 

Available 

UNK Cummins 

E55CRC-24 H 1975 Kenworth NTCC-350 350 Cummins 

E55CRC-25 H 1983 Freightliner Plate Not 

Available 

UNK Cummins 

E55CRC-26 H 1999 Freightliner C-10 270 Caterpillar 

E55CRC-27 H 2000 Freightliner Series 60 500 Detroit 

E55CRC-28 H 1999 Freightliner Series 60 500 Detroit 

E55CRC-29 H 2000 Volvo 1SX475ST2 450 Cummins 

E55CRC-30 H 1999 Freightliner Series 60 500 Detroit 

E55CRC-31 H 1998 Kenworth N14-460E+ 460 Cummins 

E55CRC-32 H 1992 Volvo 3406B 280 Caterpillar 

E55CRC-33 H 1985 Freightliner 3406 310 Caterpillar 

E55CRC-34 H 2004 Freightliner Series 60 500 Detroit 

E55CRC-35 H 2001 Sterling Series 60 470 Detroit 

E55CRC-36 H 2001 Peterbilt C-15 475 Caterpillar 

E55CRC-37 H 2004 Volvo ISX 500 Cummins 

E55CRC-38 H 2003 Volvo ISX 530 Cummins 

E55CRC-39 H 2004 Volvo ISX 530 Cummins 

E55CRC-40 H 2004 Freightliner Series 60 500 Detroit 

E55CRC-41 M 1998 Ford B5.9 210 Cummins 

E55CRC-42 H 2000 Freightliner 3406 435 Caterpillar 

E55CRC-43 H 1995 Peterbilt Series 60 470 Detroit 

E55CRC-44 H 1989 Volvo 3406 300 

(est.) 

Caterpillar 

E55CRC-45 H 1993 Volvo GM L10-280 280 Cummins 

E55CRC-46 H 1989 Volvo GM 3176 400 

(est.) 

Caterpillar 

E55CRC-47 H 1986 Ford 6V92 350 Detroit 

E55CRC-48 H 1998 Freightliner N14 Plus 447 Cummins 

E55CRC-49 H 1994 International 3406? 300 

(est.) 

Caterpillar 

E55CRC-50 M 2001 International DT466 C-195 195 International 

E55CRC-51 M 1994 International DT-408 

A210F 

210 International 

E55CRC-52 M 2002 Isuzu 4HE1-TCS 175 Isuzu 

E55CRC-53 M 2001 GMC 1GMXH08.15 

12 Gas V8 

270 GM 

13 
E55CRC-

(truck) 

M=MHDT 

H=HHDT 

Vehicle 

model 

year 

Vehicle 

Manufacturer 

Engine Model Engine 

Power 

(hp) 

Engine 

Manufacturer 

E55CRC-54 M 1983 Ford 370-2V Gas 296 Ford 

V8 

E55CRC-55 M 1992 Ford 210 210 Ford 

E55CRC-56 M 1988 Ford 3208 215 Caterpillar 

E55CRC-57 M 2000 Freightliner 3126 330 Caterpillar 

E55CRC-58 M 1982 Ford V8-8.2 4087-

7300 770 

160 

(est.) 

Detroit 

E55CRC-59 M 1990 International LTA10 300 Cummins 

E55CRC-60 H 1995 Ford L10 300 Cummins 

E55CRC-61 M 2000 1999 3126 190 Caterpillar 

E55CRC-62 H 1983 Kenworth 3406 350 Caterpillar 

E55CRC-63 H 2005 Freightliner C15 500 Caterpillar 

E55CRC-64 H 1994 Kenworth N14 310 Cummins 

E55CRC-65 H 1988 International LTA10 240 Cummins 

E55CRC-66 H 1989 International LTA10 270 Cummins 

E55CRC-67 

(not tested) 

H 1975 Ford UNK UNK Cummins 

E55CRC-68 M 1995 International DT466 C-195 230 International 

E55CRC-69 H 1989 Ford C215 215 Ford 

E55CRC-70 M 1998 Freightliner LTA10 210 Cummins 

E55CRC-71 M 1995 Ford LTA10 300 Cummins 

E55CRC-72 M(G) 1992 Ford 7.0 EFI UNK Ford 

E55CRC-73 M 1974 Ford 1150 185 Caterpillar 

E55CRC-74 H 1969 Kenworth UNK UNK Cummins 

E55CRC-75 M 1975 Ford V8-8.2 4087-

7300 C59 

UNK Detroit Diesel 

E55CRC-76 M 1993 Ford 8.3L UNK Ford 

E55CRC-77 M(G) 1987 Chevrolet V8 UNK Chevrolet 

E55CRC-78 H 1975 Peterbilt UNK UNK Cummins 

Once a vehicle was recruited, a WVU driver or WVU commercial driver (when required) 

drove the vehicle to the WVU test site. The driver inspected the vehicle before moving 

the vehicle: no vehicles were rejected on the basis of this preliminary inspection. A few 

vehicles, not licensed at the time of testing, were towed to the test site. 

Each vehicle was photographed at the laboratory site. These photographs are gathered in 

Appendix A of this report. Basic vehicle information was logged on the Vehicle 

Information Forms which are gathered in Appendix B. 

14 
EQUIPMENT & METHODS – REGULATED SPECIES 

Translab Description 

The characterization of the emissions took place using a WVU Transportable Heavy Duty 

Vehicle Emissions Testing Laboratory (Translab). The Translab incorporated a chassis 

dynamometer testbed, full scale dilution tunnel with a critical flow venturi and blower, 

70mm PM filtration system and research grade analyzers. For all of Phases 1 and 1.5 

and for the first several vehicles of Phase 2, the Translab was located at Ralphs Grocery, 

1500 Eastridge Ave., Riverside, CA. The latter part of the testing was completed at 1084 

Columbia Ave., Riverside, CA on property leased from the University of California, 

Riverside. The Translab had the same basic arrangement in all of phases of the E-55/59 

CRC Study. WVU employed two different HHDDT chassis dynamometer test beds, one 

for Phase 1 and the other for Phases 1.5, 2, and 3. These test beds were similar in design 

and calibrated to provide the same inertia and road-load characteristics. Some MHDTs 

were tested using the second HHDDT test bed, while others were tested using WVU’s 

medium-duty chassis dynamometer. The coastdown methodologies used to determine 

vehicle inertial and drag characteristics assured that loading was properly applied 

independent of which chassis dynamometer was utilized. 

The laboratory equipment, including the gaseous emissions analyzer bench, PM system 

and dilution system used, remained the same throughout the program. Procedures with 

respect to PM filter processing, analyzer calibration and background correction were the 

same for all four phases. For completeness of this report, a description of the WVU 

Translab has been included in Appendix C. 

Beginning with E55CRC-26, the laboratory used a Tapered Element Oscillating 

Microbalance (TEOM) analyzer to quantify continuous PM mass. The TEOM sampled at 

a rate of 2 liters/minute from the primary (full scale) dilution tunnel using the same port 

as the PM filter. 

In Phase 1.5, Phase 2, and Phase 3 research, exhaust temperature was measured in the 

first section of test exhaust after the tailpipe using a J-type thermocouple. Exhaust 

temperature was not measured in Phase 1 research. 

Preparation of the Vehicle for Testing 

Vehicle Inspection 

Each truck, when received at the test site, was inspected for safety, tampering or 

malmaintenance and engine control unit (ECU) status. The safety inspection was 

conducted by the truck’s test driver (who in most instances also drove the vehicle from its 

source). The vehicle was inspected for: 

• Exhaust leaks 

15 
• Air leaks in the brake system 

• Other visible brake problems (including frayed lines, damaged slack adjusters) 

• Damaged drive tires 

• Drivetrain damage (including worn universal joints) 

• Loose fan bearing or worn engine drive belts 

• Damaged vehicle controls 

Vehicle information was collected on the WVU Test Vehicle Information Sheets and they 

are included in Appendix B. The vehicle safety inspection was verified by the 

completion of WVU Vehicle Inspection Report. These sheets appear in Appendix D. 

Each vehicle was also visually inspected for T&M. This inspection procedure was 

developed in Phase 1 of this program. Items for inspection appeared in the WVU T&M 

Issues sheet for each vehicle. Copies of the WVU T&M Issues Sheets appear in 

Appendix E of this report. 

The engine control unit (ECU), in vehicles so equipped, was interrogated where possible. 

An interface and software for this interrogation, developed for use by the WVU Mobile 

Emissions Measurement System (MEMS) and used in other related programs for onboard vehicle emissions measurement1

 was used to log ECU data continuously for 

vehicles equipped with a compatible ECU. These data were transmitted to WVUMorgantown electronically as soon as they were available. In several cases, relating both 

to the system used to read the data and to the vehicle ECU, interrogation was not 

possible. All available ECU downloads are presented in Appendix F. In cases where the 

same vehicle ECU download was performed on two occasions (and was identical), only 

the first download is shown in Appendix F. 

Engine/Vehicle Preparation 

Prior to being placed on the dynamometer, each vehicle was inspected and the following 

inspections and checks were performed and recorded as the T&M report for that vehicle: 

•Engine oil, power steering fluid, and coolant levels confirmed to be in operating range. 

• Fuel tanks filled to provide sufficient fuel for the entire testing procedure (typically 3⁄4 

tank for multiple weights with repeated runs or 1⁄2 tank for testing at one or two 

weights with single runs). 

• Inspection for signs of fuel, oil, and coolant leaks from the vehicle. 

•Exhaust after-treatment devices, when installed, inspected and model/type recorded 

and compared to specifications provided on engine and vehicle data plates. 

•Condition of the air filter checked air cleaner service indicator checked and, if the air 

filter was severely blocked, project supervisors and sponsors contacted prior to fitting 

with a new filter. 

• Fuel sample (32 oz.) and oil sample (4 oz.) take for post testing analysis. 

•Exhaust system inspected for leaks. 

•Engine checked for excessive/irregular noise and malfunctions in the cooling system. 

16 
Wheel-Hub Adapter Installation 

In order to connect the drivetrain of the vehicle to the dynamometer components, the 

outer wheels of the dual wheel set were removed on the forward-most drive axle and 

replaced with rims designed to accept specially designed adapters. The inside tires were 

checked for any cuts and bulges and tire pressure was verified/adjusted to be within +5 

psi of the manufacturer’s maximum tire pressure specifications. 

For vehicles equipped with a power divider, the power divider was locked in. 

Using the information stamped on the vehicle tires, the rolling diameter was determined 

and recorded into the vehicles database to allow for the proper dynamometer flywheel 

selection. 

Certain MHDT were characterized using a medium-duty chassis dynamometer test bed. 

In these cases the installation on the dynamometer was conventional. Power was taken 

from the vehicle’s wheels by the rollers, and no hub connection was employed. 

Test Vehicle Mounting 

In order to mount the vehicle onto the dynamometer, ramps were installed and the vehicle 

was backed on to the test bed with the driven wheels (forward wheel set in the case of 

dual axle vehicles) centered over the front set of rollers. The vehicle axles were then 

attached to the dynamometer bed using chains to prevent both forward-aft and side-toside motion. The hub adapters were then connected to the dynamometer drivetrain and 

the front of the vehicle was raised to level the vehicle. 

If excess tire side wall deflection was observed (or later if tire heating became an issue) 

on vehicles with single rear axles, the rear of the vehicle was supported partly using 

jacks. Up to 50% of the normal weight was removed from the single wheel (which 

normally would share the weight with another wheel). Scales were used beneath the 

jacks to verify the amount of weight reduced. 

Connections of Vehicle to Laboratory 

A monitor, used by the driver to observe the target and actual vehicle speed, was placed 

in the vehicle. The exhaust of the vehicle was routed to the dilution tunnel using 

insulated, flexible exhaust tubing. 

Pre-test Vehicle Operation 

Prior to operating the vehicle, the test engineer estimated the dilution tunnel flow rate that 

would provide the optimum balance between providing sufficient flow to maintain the 

particulate filter face temperature below 125OF while not over diluting the exhaust such 

that emissions concentrations could be accurately measured by the laboratory analyzers. 

After starting the dilution tunnel blower, the vehicle engine was started and operated 

17 
throughout its range while the safety officer inspected the exhaust system (including both 

the vehicle exhaust and the exhaust transfer tube) for leaks. 

In cases where the vehicle would not start after 10 seconds of cranking, technicians 

investigated to determine the cause for the failure and attempted to affect repairs. 

At all times, the vehicle was operated a manner representative of in-use operation, and 

where appropriate and available, according to the manufacturer’s recommendation. For 

vehicles equipped with automatic transmissions, idle modes less than one minute in 

duration were run with the transmission in “Drive” and the brakes applied. In the case of 

vehicles equipped with manual transmissions, the vehicles were run in gear with the 

clutch disengaged. 

Vehicle Driving Instructions 

During high acceleration portions of the trace, the vehicle was driven at maximum power 

while in gear with the clutch engaged, but the gears were changed in the same manner 

that they would be changed while driving on the road. The gears were not "crashed" 

aggressively to keep up with the trace. Conversely, the vehicle was not driven with 

casually slow shifting. The objective during acceleration was not solely to match the 

trace as closely as possible, but also to mimic the way in which the subject vehicle would 

actually accelerate on the road. 

During braking events, where that portion of the trace ended at zero velocity (idle), the 

driver would downshift during braking at speeds above 15 to 20 miles per hour. Below 

15 to 20 miles per hour, brakes alone were used. In many 9 and 10 speed transmissions 

with typical over-the-road gear ratios, this would typically mean that downshifting would 

continue until the highest gear in low range (5th gear in a 10 speed, 4th gear in a "L plus 

8" 9 speed configuration) was attained. When the deceleration did not reach zero, but 

blended into another acceleration ramp, or a cruise section, gears were used throughout to 

maintain normal on-road driving practice. 

The driver selected gears based upon judgment of the gears that would be used on the 

road. For example, the driver did not take off in the lowest gear if a higher gear would be 

the norm in use. In driving 13 and 18 speed (ranged and split) transmissions, it was not 

considered necessary to use all gears and typically splitting was not performed in this 

case. However, 10 speed splitter transmissions were not driven as 5 speed units at high 

inertial loads. 

Vehicle Practice Run 

For each vehicle, a practice test was performed. This served to help the driver familiarize 

himself with the driving/shifting/braking characteristics of the vehicle while the ranges of 

the gaseous emissions analyzers were set. The practice run also allowed the test engineer 

to ensure that the dynamometer was loading the vehicle properly. 

18 
If the driver did not follow the trace properly, variances were recorded in the comments 

section of the test report and an explanation was offered. If any abnormality was 

observed during this practice run, the supervising engineer was informed. 

Test Run Procedures 

Overall Vehicle Test Procedure 

Background PM samples were taken at the beginning and end of each test day, unless 

otherwise designated by program requirements. 

To execute a hot test, the truck was warmed through operation on or off the dynamometer 

until it had reached an operating temperature that caused the radiator to engage in 

cooling. This may be judged by the heat of the radiator or opening of the thermostat. 

Alternately, it was considered sufficient that the truck was operated for a cycle with a 

minimum duration of 10 minutes with a minimum energy intensity of 7.5 x 10–6 cycle 

energy per mile per mass of vehicle (axle hp-hr/lb.-mile). Cycles meeting this criterion 

include the WVU 5mile route, the CSHVR, the UDDS, and the Transient and Cruise 

modes of the California Heavy Heavy-Duty Diesel Vehicle Test (HHDDT) cycle. It is 

acknowledged that when cold weather testing is performed, these cycles may not warm 

the vehicle to the point that the radiator is in use but the vehicle was deemed to be at 

operating temperature under those ambient conditions. No cold conditions were 

encountered during the testing in Riverside. The truck was keyed off 30-60 seconds after 

the end of this warm-up. 

The test schedule commenced no later than 20 minutes after the warm-up but not before 

10 minutes after the warm-up. If the20 minute period was exceeded, another warm-up 

was required. These criteria were based on a prior study that evaluated HHDDT schedule 

repeatability. Based upon measurements of emissions during the warm-up, analyzers 

were re-ranged during this 10 to 20 minute period as required. The vehicle was started 

and allowed to idle between 30 and 60 seconds prior to the beginning of the test and, after 

the completion of the test, the vehicle was idled for 30 seconds and then keyed off. 

During the 10 to 20 minute period between tests, integrated and background bags were 

analyzed, particulate filters were changed out and analyzers were checked for drift by 

checking their response to samples containing 0% and 100% of the respective analysis 

gas. 

Gaseous and PM sampling system 

WVU’s Total-Exhaust Double-Dilution Tunnel 

19 
Diluted 

Exhaust 

Vehicle 

Exhaust

4 

3 

7 

8 

DRI 

1 

2 

Dilution 

Air 

Overflow 

5 

9 

ATOFMS 

HEPA

Filtered

Dilution

Air

Figure 1: WVU Sampling System Schematic. 

Figure 1 shows the WVU double dilution tunnel. A description of the various 

components on WVU’s sampling system is given in Table 9. This table includes details 

of the DRI residence chamber and the sampling for non-regulated species from the 

chamber. 

20 

6 
Table 9: Sampling system description and media type. 

ID Sample Description Media Type 

Phase 1 Phase 2 

1 HC Heated FID Analyzer Heated FID Analyzer 

2 CO/CO2 NDIR Analyzers NDIR Analyzers 

3 NOx Chemiluminescent Analyzer Chemiluminescent Analyzer 

4 TEOM TEOM Filter TEOM Filter 

5 TPM 70 mm T60A20 70 mm T60A20 

6 PM10 Fraction for Gravimetric 

Analysis 

URG Model 2000-30 EA 

Cyclone @ 28.3 lpm ; 47 mm 

TX40HI20WW Filters 

URG Model 2000-30 EA 

Cyclone @ 28.3 lpm ; 47 mm 

TX40HI20WW Filters 

7 MOUDI Greased Aluminum 

Substrates; TX40HI20WW 

Afterfilter 

Not Applicable 

8 DRI Dilution Chamber. 

The chamber diluted exhaust from 

WVU’s tunnel through two PM2.5 

cyclones. 

Model Bendix-Unico 240 

Cyclones@113 lpm 

Model Bendix-Unico 240 

Cyclones@113 lpm 

Volatile Organic Compounds (VOC) Canister, Field GC Canister, Field GC 

Methane Canister Canister 

Semi-volatile Organic Compounds 

(VOC) 

PUF/XAD and TIGF Filters PUF/XAD and TIGF Filters 

SVOC – Low Molecular weight TENAX Tubes TENAX Tubes 

Nitro-PAH PUF/XAD and TIGF Filters PUF/XAD and TIGF Filters 

Carbonyls DNPH Cartridges DNPH Cartridges 

Nitrosamines Thermosorb Cartridges Thermosorb Cartridges 

PM, SOF, Organic Compounds TIGF Filters TIGF Filters 

Elemental Analysis and 

Gravimetric Analysis (PM2.5) 

TIGF Filters TIGF Filters 

Ammonium and Ions (Nitrate, Nitrite, 

Chloride, Sulfate) 

Quartz Filters Quartz Filters 

EC/OC Quartz Filters Quartz Filters 

9 Particle Analysis by Mass 

Spectroscopy 

ATOMFS ATOMFS 

10 Real-time PM Size Distribution DMS 500 

Total Particulate Matter 

Total Particulate Matter (TPM), as defined by the US EPA, is sampled by filtering diluted 

diesel exhaust at filter face temperatures of less than 52oC (125o F). TPM has been 

reported as a regulated emission species. A 70mm filter holder was connected that 

contained two 70mm T60A20 fiberglass filters, the primary and secondary filters to 

capture the regulated TPM. 

21 
Gas Analyzer Operation 

Pre-Test Procedure 

Prior to initiating each test, the background and integrated/dilute bags were evacuated to 

ensure that no sample was left in them from the previous test. Since the HC and NOX 

analyzers were sensitive to temperature changes, their sample pumps were started at least 

1 hour prior to starting an emissions test. The particulate filter holder was loaded with 

conditioned and weighed primary and secondary filters and connected to the secondary 

dilution tunnel. With the sample pumps and analyzers operating and sampling from the 

dilution tunnel, sample flow rates were adjusted to meet specifications and maintain testto-test consistency. 

In-Test Procedure 

At the onset of the data collection phase of each test, the gas operator ensured that the fill 

rates for the dilute and background bags were sufficient to provide enough sample for 

two analyses if required. The flow rate through the particulate filter was checked against 

the setting for the test (typically 2-4 scfm depending on PM loading and outside 

temperature). During a test, the engineer and gas operators monitored the responses of the 

dynamometer controls and emissions analyzers to ensure that they were operating 

properly. A safety operator, stationed at the dynamometer, watched for inconsistencies in 

vehicle or dynamometer operation. The most common vehicle problem involved tire 

degradation during the test due to overheating which was compensated for by the safety 

operator applying a water spray to the tires. The test engineer also reviewed the data 

collected during the previous test to ensure that the various lab analyzers and sensors had 

operated correctly. 

Post-Test Procedure 

At the conclusion of the test, the particulate filter holder was disconnected from the 

secondary dilution tunnel and the loaded particulate filters were placed stored in an 

environmental chamber for conditioning. The integrated and background bags were 

analyzed for HC, NOX, CO, CO2 concentration and the levels were recorded. The CO and 

CO2 concentrations from integrated and continuous measurements were compared to 

ensure that they agreed to within 5%. 

Calibration Procedures 

Sensors and analyzers were calibrated per the manufacturer’s recommendation and per 

Title 40, Part 86 of the CFR. Calibration procedures for the entire laboratory were 

followed for each analyzer when the calibration gas source was changed or after analyzer 

repair. 

22 
Particulate Matter Filter Conditioning and Weighing 

The relative humidity and temperature of the environmental chamber, used to condition 

particulate filters before weighing, were maintained at 50% (+/-10%) and 70 oF (+/- 10 o

F). Filters were stored in petri dishes that were cleaned using alcohol and lint free cloth 

prior to use. Filters were conditioned in the environmental chamber for a minimum of 5 

hours before weighing. A set of two particulate filters were kept in the chamber and 

weighed each time filters were weighed to check for possible problems with either the 

weighing instrument or the environmental chamber. Filter weight was determined using a 

CAHN-32 microbalance which was calibrated using a NIST traceable 200 mg calibration 

weight. 

Speciated analysis of filters, performed by DRI, is discussed in Appendix G. 

Forms 

A set of forms, shown in the Quality Assurance Program section were filled out by the 

field engineers/technicians during vehicle emissions evaluation tests: 

Quality Assurance/Quality Control and Emissions Data Report 

Field Custody Log 

Analyzer Check-off Sheet 

Analyzer Calibration Record 

Test Vehicle Information Sheet 

Vehicle Test Sequence 

Vehicle Inspection Form 

T&M Issues Form 

The “Test Sequence” form was designed to enable WVU field engineers keep track of the 

tests that have been completed. The “Test Sequence” depicts tests in the correct 

chronological order. 

Test sequence numbers are employed by WVU to keep track of all tests in its database. 

This is WVU’s primary means of accessing test results for any vehicle evaluated in the 

past 12 years. Each test sequence number has several run numbers associated with it. 

Test Cycles 

Each vehicle was tested using a suite of test schedules which varied between phases, and 

between HHDDT and MHDT. The target cycles and modes are shown graphically in 

Appendix H of this report. The UDDS was used for all classes of vehicles. For the 

HHDDT, the HHDDT Schedule2

, consisting of four modes (Idle, Creep, Transient and 

Cruise), was also used. The trucks were tested at 56,000 lbs. simulated weight on the 

UDDS and the HHDDT Schedule, plus a high-speed cruise mode created for Phase 1.5. 

The high-speed cruise mode caused high dilution tunnel and tire temperatures during 

testing and was shortened in duration at the beginning of Phase 1.5, after which it was 

23 
termed the “HHDDT Short” (HHDDT_S). In Phase 1.5, the five modes of the HHDDT 

schedule were also used to characterize emissions at 30,000 lbs. and 66,000 lbs. test 

weights, after preliminary work suggested that the original 75,000 lbs. maximum target 

weight placed too much stress on both truck brakes and the dynamometer. This mode 

was intended for use in testing all HHDDT. HHDDT_S has a maximum speed of 67 mph 

and an average speed of slightly over 50 mph. In some cases trucks were governed at a 

sufficiently low road speed so that the HHDDT_S mode could not be executed 

reasonably. In these cases, as judged by the WVU field engineer, no HHDDT_S mode 

was attempted. 

Table 10 shows the time duration, average speed, and distance covered for each cycle or 

mode, and the computer code used to describe that cycle or mode. 

Table 10: Test Schedule Summary. AC5080 performance depends on truck power to 

weight ratio. 

Code Schedule Time(sec) Ave 

Speed 

Distance 

(miles) 

TEST_D UDDS 1060 18.8 5.5 

IDLE32 HHDDT 

idle 1800 0 0 

CREEP34 HHDDT 

creep 

1032 1.7 0.5 

TRANS3 HHDDT 

Transient 688 14.9 2.9 

CRUISE3 HHDDT 

cruise 2083 39.9 23.1 

HHDDT_S HHDDT 

short 760 49.9 10.5 

MHDTLO 

MHDT 

low speed 

transient 

370 9.4 1.0 

MHDTHI 

MHDT 

high-speed 

transient 

1190 21.6 7.1 

MHDTCR MHDT 

cruise 1910 40.1 21.3 

AC5080 AC5080 

idle 10 sec 

50kph 60 sec 

80kph 80 sec 

N/A N/A 

For those HHDDT subject to further chemical analysis, the Idle, Creep, Transient, and 

Cruise and higher speed modes were each repeated. In order to collect sufficient mass for 

speciation, it was necessary to increase the length of some of the modes. For example, 

the mode denoted creep34 consisted of four HHDDT creep (creep3) modes in a sequence 

sampled as a single cycle. Similarly idle32 consisted of two idle runs together (i.e. the 

idle time was doubled). 

24 
For the MHDT not subject to speciation, the AC5080 and the MHDT Schedule were 

added to the UDDS. The MHDT schedule consisted of three modes: lower speed 

transient (MHDTLO), higher speed transient (MHDTHI), and cruise (MHDTCR)3,4 In 

Phase 2, for three of these vehicles, the HHDDT_S mode was included in the MHDT 

schedule. In Phase 3, all MHDT judged capable of adequately maintaining the necessary 

speed ran the HHDDT_S. For the one medium-heavy-duty vehicle subject to further 

chemical analysis in Phase 2, idle (not included on the other MHDT vehicles), lower 

speed transient, higher speed transient, and cruise modes were each repeated to create 

paired data sets at the laden weight. 

The AC5080 is a short test proposed as an Inspection and Maintenance (I/M) cycle5

. It is 

a mixed-mode test having two full-load accelerations and two steady-state cruises at 50 

km/hr (31.1 mph) and 80 km/hr (49.7 mph). It is less aggressive than the DT80, but 

according to its creators it may be more representative of on-road driving. It requires the 

use of an inertia-simulating dynamometer. WVU developed a specific protocol for 

implementing the AC5080 Short Test because the previous descriptions of the cycle were 

ambiguous in the cycle execution. 

The AC5080 test has two full-power accelerations and two steady-state cruises as shown 

in Table 11 and Figure 2. Since the time of occurrence of points "C" and "E" are vehicle 

and load dependent, the scheduled speed trace (the speed-time line that the driver is 

expected to follow) was generated in real time. When the program had finished 

initializing, the instruction "Start the Engine" appeared on the screen accompanied by 

three horn blasts. The driver then started the engine immediately and allowed it to idle. 

After sixty seconds, data capture commenced. This corresponds to point "A" on the Test 

Schematic. Ten seconds later, a ramp was drawn on the driver's display. This ramp was 

generated to reach point "C" in around six seconds. The driver was expected to treat this 

as a "free" acceleration (maximum acceleration, while driving in a normal style), and to 

reach the steady state speed of 50 Km/hr (31.1 mph) as quickly as possible. Once the 

vehicle reached 48 Km/hr (30 mph), point "D" is defined, at exactly sixty seconds in the 

future. When this time had elapsed, the second rapid acceleration ramp was generated. 

This ramp was drawn to reach point "E" in about 4.5 seconds. When the vehicle speed 

reached 78.5 Km/hr (49 mph), point "F" was defined to be 80 seconds later than this 

time. Upon reaching point "F," the data acquisition was stopped and the driver was free 

to slow the vehicle speed in the safest manner. The 49 mph value was determined to be a 

lower bound of approximation to reaching 50 mph. An actual test is shown in Figure 3. 

25 
Table 11: AC5080 Methodology. 

Path Description Duration 

A – B Idle. Select low gear. 10 seconds 

B – C Rapidly accelerate to 50 km/hr (31.1 mph) Vehicle Dependant 

C – D Maintain 50 km/hr. (31.1 mph) 60 seconds 

D – E Rapidly accelerate to 80 km/hr (49.7 mph) Vehicle Dependant 

E – F Maintain 80 km/hr. (49.7 mph) 80 seconds 

F - G Return vehicle to stop with engine at idle. Vehicle Dependant Vehicle Speed (mph) 

60 

50 

40 

30 

20 

10 

0 

A B C D E F G 

Figure 2: AC5080 Short Test (time not to scale). 

26 
60 

55 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

Vehicle Speed (mph) 

0 50 100 150 200 250 

Time (s) 

Figure 3: The AC5080 Schedule as driven by a 1990 Kenworth road tractor with a 

370 hp Cummins M11 engine and a 10-speed manual transmission, with a simulated 

vehicle test weight of 56,000 lbs. 

Test Weights 

All of the HHDDT tested in this study were deemed to have gross vehicle weights of 

80,000 pounds, in that they were all typical over-the-road tractors. The GVWR displayed 

in the cab of such tractors may vary from 30,000 lbs. (for single axle trailers) to over 

52,000 lbs. (for tandem axle trailers), but trailer weight is not considered in these GVWR 

values. For tractor-trailers, it is the combination weight that is of interest, rather than the 

tractor weight. The test weight used for all vehicles was planned to be 56,000 lbs., 

representative of laden use. The test weights for Phase 1.5 were planned to be 30,000 

lbs., 56,000 lbs. and 75,000 lbs. However, it was evident that the 75,000 lbs. operation 

proved stressful to the truck brakes because only one or two axles were being used to 

slow an inertia that would be slowed with five axles in normal on-road use. Also, the 

accelerations and decelerations at 75,000 lbs. showed potential to cause dynamometer 

damage. Some preliminary test runs, presented in Figure 4 and Figure 5, showed that a 

difference still existed in emissions between 56,000 lbs. and 66,000 lbs. operating weight, 

and so the 66,000 lbs. weight was used as a maximum weight test weight instead of the 

75,000 lbs. weight for the remainder of the program. PM increased monotonically with 

test weight for the Transient Mode, but did not change appreciably between the 56,000, 

66,000, and 75,000 lbs. runs on the HHDDT_S, where wind drag becomes more 

important. For the case of NOx (see Figure 5), the Transient mode NOx emissions at 

66,000 lbs. were substantially higher than at 75,000 lbs. 

27 
g/mile 

1.6 

1.4 

1.2 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

Transient 

Cruise 

HHDDT_S 

30,000 56,000 66,000 75,000 

Simulated Test Weight 

Figure 4: PM emissions for vehicle E55CRC-27 which was tested at four weights, 

before 66,000 lbs. was adopted as the highest test weight. 

35.0

Transient

Cruise 

HHDDT_S 

30.0 

25.0 

20.0 

30,000 56,000 66,000 75,000 

Simulated Test Weight 

g/mile 

15.0 

10.0 

5.0 

0.0 

Figure 5: NOx emissions for vehicle E55CRC-27 which was tested at four weights, 

before 66,000 lbs. was adopted as the highest test weight. 

28 
The MHDT were tested at both laden and unladen weights. Laden weight was set to be 

75% of the gross vehicle weight rating (GVWR). The unladen weight was set at 50% of 

the GVWR. 

Figure 6 shows an example of the monotonic increase in distance-specific emissions of 

PM as test weight increases. Figure 7 shows that, with the exception of the AC5080 

driving schedule, NOx emissions increased with test weight as well. These emissions 

differences vindicated the effort associated with testing at two weights. 

0.000 

0.005 

0.010 

0.015 

0.020 

0.025 

g/mile 

75% GVWR 

50% GVWR 

75% GVWR 0.020 0.014 0.001 0.023 0.004 

50% GVWR 0.006 0.009 0.001 0.000 0.001 

AC5080 MHDTCR MHDTHI MHDTLO TEST_D 

Figure 6: PM emissions for vehicle E55CRC-53 tested at two weights 

29 
0.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

7.0 

8.0 

g/mile 

75% GVWR 

50% GVWR 

75% GVWR 5.60 5.47 4.58 7.42 3.67 

50% GVWR 5.92 4.22 3.17 4.39 3.10 

AC5080 MHDTCR MHDTHI MHDTLO TEST_D 

Figure 7: NOx emissions for vehicle E55CRC-53 tested at two weights. 

30 
EQUIPMENT AND METHODS – NON-REGULATED SPECIES & PARTICLE 

SIZING 

DRI’s Residence Time Dilution Tunnel 

DRI provided a “residence time dilution sampling system” for sample collection during 

Phase 1 and Phase 2 of this study. The dilution tunnel was identical to those used during 

the Northern Front Range Air Quality Study and it was based on a dilution stack sampler 

designed and tested by a group led by Dr. G.R. Cass6

. Figure 8 shows a schematic of the 

DRI sampler. Because of the short sampling time and generally low PM emission rates 

expected for certain cycles (particularly the Idle mode), the sampler was used without 

dilution as a residence time chamber only. The dilution sampler was interfaced with the 

WVU dynamometer dilution system. The samples were drawn through cyclone 

separators with a cut-off diameter of 2.5 mm, operating at 113 lpm and collected using 

the DRI Sequential Filter Sampler (for inorganic species) and the DRI Sequential Fine 

Particulate/Semi-Volatile Organic Compound (PSVOC) Samplers for organic species. In 

addition, a separate sampling line (without cyclone) was used for collecting canisters, 

DNPH cartridges and Tenax samples. The details of sample collection techniques are 

described in the appropriate standard operating procedures (SOPs) and are available upon 

request from the Organic Analytical Laboratory (OAL) of DRI. 

31 
Figure 8: Schematic of DRI dilution tunnel sampler (Hildemann, et al.6) 
Mini Dilution System 

The Scanning Mobility Particle Sizer (SMPS) employed a mini dilution tunnel to dilute 

the raw exhaust for sampling. The DMS 500 did not employ this mini dilution tunnel, but 

was used to sample directly from the main CVS tunnel. 

The mini dilution system shown in Figure 10 incorporated a tunnel with its length 

maintained at ten times its diameter to facilitate good mixing and uniform distribution at 

the sampling zone. An orifice plate was provided at the inlet of the dilution system to 

ensure proper turbulence. The tunnel was wrapped with heating tape and insulation to 

maintain a temperature of 46o C (115o F) to prevent water condensation. A dilution ratio 

of 1:30 was maintained throughout this study. A 12 cm (5 inch) exhaust coupling with a 2 

cm (3⁄4 inch) probe welded on its body was used to draw a partial sample from the raw 

exhausts shown in Figure 9. One end of the probe had a quick disconnect fitting for ease 

of coupling the probe to the mini dilution tunnel. The sampling was not isokinetic. The 

sample line from the probe to the mini dilution tunnel was kept as short as possible and 

well insulated. Dilution air was supplied immediately before the mixing orifice by a 

separate pump. The dilution air was passed through a refrigerated dryer and a HEPA 

filter to provide particle and moisture free air. A separate vacuum pump was used to draw 

in the exhaust sample. 

Raw Exhaust 

5 Inch 

Exhaust 

Coupling 

3/4 Inch 

Probe 

Figure 9: Exhaust Coupler with Sampling Probe for mini dilution tunnel 

33 
Mini Dilution Tunnel 

70 mm Filter Holder 

Diluted Exhaust Co 2 Sample 

Temperature Controllers 

Refrigerated Dryer 

(Dilution Air) 

Heat Exchanger 

(Dilution Air) 

Mini Tunnel Vacuum Pump (Dilution Air) 

Dilution Air Pump 

West Virginia Un i ve rsi ty 

ECU 

Ch iller 

TEXTEXET 

Tunnel 

Pressure 

Co Sa

2

Co By

2

2 

Mass Power 

Co An

Data A

ThermCondit

Dual C

Raw 

Heater 

Dilutio

Figure 10: West Virginia University-Mini Dilution System 
Both the dilution air and total air flow rates were controlled by two Sierra mass flow 

controllers calibrated from 0 to 200 slpm (0 to 7 scfm). Sampling probes were installed 

ten diameters downstream of the mixing orifice to ensure uniform concentration. A dual 

range CO2 analyzer was used to measure the raw and dilute CO2 concentrations. A 10-

point analyzer calibration was employed using 15% and 1% CO2 bottles. The analyzer 

was checked everyday for a zero and span using nitrogen as zero gas and 15% and 1% 

CO2 bottles as span gas for the analyzers. The raw and dilute exhaust gases were filtered 

by inline filters and chilled by thermoelectric chillers for removal of particulates and 

moisture, respectively. The filters were checked every day and replaced if necessary. A 

purge air supply for the CO2 analyzers was provided by an external oil free compressor 

through a HEPA filter. This purge air was useful in flushing the analyzer of any residual 

gas present, which may provide erroneous readings. 

The mass flow controllers and the CO2 analyzers were connected to a data acquisition 

system (National Instruments DAS 6020-E BNC). A program in Visual Basic was 

developed by WVU to control the data acquisition system (DAS) pad and to save 

continuous data from the analyzer and the mass flow controller. Other parameters such as 

tunnel pressure, and temperature were also recorded on a continuous basis. The DAS pad 

also maintained the user defined dilution ratio. The desired dilution ratios were achieved 

in two ways, first a flow-based system and the other is a CO2 based system. With the 

flow based system, the dilution ratio was calculated using the following equation: 

DR = total / (total – dilute) 

The dilution ratio was maintained by adjusting both the total and dilute flow rates. The 

total and dilute flow rates were measured and set by the mass flow controllers. The CO2-

based system measured the raw and dilute CO2 concentrations and the dilution ratio was 

the simple ratio of raw to dilute concentrations. The dilution ratio was maintained by 

controlling the mass flow controllers based on the CO2 readings. Through experience it 

had been determined by WVU that the flow based system was more accurate in 

controlling the dilution ratio and the CO2 readings were used to verify the set dilution 

ratio. It may be argued that the dilution ratios may be better controlled using CO2 

concentrations than using mass flow controllers. WVU has both systems on the minidilution tunnel that is used for PM sizing work. Problems associated with deskew times, 

gas dispersion in the tunnel, and chillers complicate the CO2-based control method, 

especially during transient tests. Over steady state tests, the CO2-based dilution ratio 

control can be very accurate. One probe was installed next to the dilute CO2 probe for 

particle size distribution measurements using the SMPS. Carbon impregnated electrically 

conductive Tygon tubing was used to transfer the sample from the tunnel to the 

instrument. This tubing was used to prevent any particle losses due to electrostatic 

deposition on the walls of the sampling tube. 

Exhaust pulsations from the engine were encountered during this study and an exhaust 

pulsation damper was devised, as shown in Figure 12. The damper consisted of a 5 gallon 

tank with one end cut off and sealed with a rubber diaphragm. The rubber diaphragm was 

35 
helpful in reducing the exhaust pulsations. The top of the tank had a tee connection which 

incorporated a straight probe as seen in Figure 11, to minimize particle losses into the 

damper. This system provided a pulsation free stream of sample with minimal particle 

loss. The damper was flushed with particle free air and evacuated after every test to 

remove any remaining particles or even volatile compounds, which may have found their 

way into the damper. This was done because the volatile compounds may adhere to the 

walls of the damper and subsequently form particles and create sampling artifacts. 

Straight probe 

Pulsation 

pressure 

acting on 

rubber 

Pulsation free sample to SMPS Sample 

from Mini 

Tunnel 

Figure 11: Schematic Representation of the Damping System 

Figure 12: Exhaust Pulsation Damper 

36 
Particle Sizing with the SMPS 

The SMPS consists of two basic components, the Electrostatic Classifier or the Mobility 

Analyzer and a Condensation Particle Counter. The use of the classifier to produce 

monodisperse aerosols is illustrated in Figure 13. The classifier or mobility analyzer 

separates particles based upon their electrical mobility and the resulting particles are 

transported to the particle counter to obtain number concentrations. In mobility analyzers 

particles are first charged, and then the aerosol is classified in a high electric field 

according to the electrical mobility of the particles. The particle size distribution is 

obtained on the basis of the relationship between mobility and sizes. The ultimate size 

parameter determined from electrical mobility measurements is the equivalent mobility 

diameter. 

Polydisperse 

aerosol 

Impactor 

Kr-85 

Bipolar 

Charger 

Sheath Air 

Particles of same 

mobility 

diameter passing 

through te slit 

Monodisperse 

aerosol 

Bypass air 

High 

Voltage 

Power 

Supply 

Figure 13: Differential Mobility Analyzer 

The inlet of the classifier has an impactor which removes all particles above 1μm since 

large particles tend to have multiple charges and stripping these charges is very difficult. 

The impactor has a nozzle and an impactor plate and different size orifices (0.071 and 

0.0475 cm) are used depending on the flow rate. The polydisperse aerosol passes through 

37
the bipolar charger containing a radioactive source (Krypton), which exposes the aerosol 

particles to high concentrations of bipolar ions. The particles and ions undergo frequent 

collisions due to random thermal motion of the ions. After reaching a state of 

equilibrium, the particles carry a bipolar charge distribution. The polydisperse aerosol 

passes into the DMA between the sheath flow, which creates an air curtain, and the outer 

cylinder. The central rod is charged with a high negative voltage and the positive 

particles are attracted to the rod. Particles with high mobility precipitate at the top end of 

the rod and particles with low mobility exit the DMA along with the bypass air. Only 

particles with a narrow mobility range exit the DMA through the slit as monodisperse 

aerosol, which pass on to the Condensation Particle Counter for concentration 

measurements. 

To obtain a full scan of the particle sizes, the voltage in the central rod of the classifier is 

increased exponentially with respect to time which is termed the up-scan of the DMA and 

the voltage is dropped to zero which is termed as the down-scan. The up-scan and downscan times are typically 120 and 15 seconds, respectively. These times can be increased 

by the user to obtain a better resolution if the particle concentrations are steady. 

The Condensation Particle Counter (CPC), also called the condensation nucleus counter 

(CNC), is the most common instrument used to determine number concentrations of 

diesel particles. Upon entering the CPC the aerosol stream is saturated with alcohol 

(typically butanol) vapor. As the mixture is cooled in the condenser tube, the vapor 

becomes supersaturated and condenses on particles. As a result, the particles grow to a 

diameter of about 10 μm, allowing for optical detection. Particle size detection limit in 

the CPC is related to the increasing saturation ratio which is required with decreasing 

particle diameters. Modern CPCs have detection limits of around 3-10 nm. 

CPCs can be operated in two modes: (1) the counting mode and (2) the opacity mode. In 

the counting mode, pulses of scattered light from individual particles are counted. This 

mode provides the most accurate measurements, but can be used only at low particle 

concentrations. In the opacity mode, used for concentrations above 104

/cm3, number 

concentrations are determined from the total scattering intensity. This mode, generally 

subject to a larger error, requires that all particles grow to the same diameter and that the 

optical system be frequently calibrated. The CPC instrument is very sensitive to the 

ambient temperature, which affects the degree of supersaturation, as well as to 

positioning and vibrations. For these reasons, it is suitable primarily for laboratory 

measurements and its use for in-field measurements is more challenging. The CPC is 

used for particle detection in many aerosol size distribution measurement instruments. 

Both the CPC and the Electrostatic Classifier make up the SMPS system. The CPC and 

the classifier are interfaced with an analog BNC connector cable. A personal computer 

with custom software provided by TSI was used to record data and control the classifier. 

A TSI model 3936 SMPS system was used for this study (Figure 14). DMA models 3081 

(Long DMA) and 3085 (Nano DMA) were used interchangeably to obtain a full particle 

size distribution down to 4 nm and up to 800 nm. A Model 3025A CPC was used for 

38 
particle counting since it could detect particles with diameters as low as 3 nm and had a 

response time of one second. 

The SMPS is basically designed for steady state operations, where the exhaust 

characteristics are invariant with time; that is, the engine is at a constant load and RPM or 

when the vehicle is operated at a constant speed. During these steady states, 

concentrations of all particles are almost constant, but the concentrations vary whenever 

the load or speed of the engine/vehicle varies. For transient measurements of the 

engine/vehicle, the engine/vehicle was first operated on a steady state mode and a full 

size scan was obtained. Particle sizes were chosen from the full scan and the number of 

particles chosen was dependent upon the number of times the vehicle was operated 

through the transient cycle. For transient tests, the classifier operated in manual mode, 

which allowed the user to enter a particular particle size and track the concentration of 

that particular size for the entire test. 

Figure 14: TSI Model 3936 SMPS System 

To assure accurate measurements, the SMPS was flow calibrated before the start of the 

project. An electrospray aerosol generator was used to calibrate the SMPS. The generator 

was capable of producing 15, 30 and 70 nm sucrose particles. Leak checks were 

performed every day to ensure that the SMPS had no leaks. Two types of leak checks 

were performed, a HEPA filter check and a zero voltage check. Since HEPA filters have 

high filtration efficiencies, a HEPA filter was connected to the inlet of the SMPS and a 

full size scan was performed. If any particles were detected above the noise level of the 

instrument, which was typically 1x103

 particles/cm3, then a thorough leak check was 

performed according to the instrument instruction manual. The second method required 

the voltage on the collector rod to be set at zero and checked for any particles being 

measured by the CPC. Since the voltage on the collector rod determines the particle size 

that exits the classifier, a zero voltage on the rod should ensure no particles exit the 

classifier. Both these methods were used everyday to make sure the SMPS had no leaks. 

If any leak was detected in the system, the manufacturer’s leak check procedure was used 

to track and solve the problem. The inlet nozzle on the classifier was cleaned everyday 

with alcohol to remove any particle deposits, which may block the flow. The impactor 

plate was also cleaned with alcohol and a thin layer of vacuum grease was applied to 

prevent particle bounce. 

39 
Particles are classified in the DMA by increasing the voltage exponentially and the 

particles leaving the classifier are increasing in size. The particles are then counted by the 

CPC and the values for concentrations for each particle size are stored in the PC as raw 

counts. The particle size obtained from the raw data assumes that each particle has a 

single charge on it after passing through a bipolar charger, which is not actually true. 

Multiple charges on a particle increase its mobility and can be incorrectly binned into the 

smaller diameter range. TSI uses an inbuilt algorithm in its SMPS software (Aerosol 

Instrument Manager-SMPS) to correct for multiple charges based on Fuchs-Gunn aerosol 

charging theory and a truncated triangular transfer function based on Knutson and 

Whitby7

. 

The software provided by TSI to record only CPC concentrations (Aerosol Instrument 

Manager-CPC) does not provide any algorithm for the reduction of data. The single 

particle charge correction, transfer function and efficiencies of the CPC and impactor 

have to be applied to the raw data. Two programs were developed in MathCAD, one to 

reduce the CPC data and the other to correct the SMPS data for the dilution ratio 

(Appendix I). The final data for the SMPS were presented as particle size based 

concentration variations with concentrations in normalized units of particles/cm3 

(dN/dlogDp). A log normal distribution was found to fit the data from the SMPS very 

well. The final data from the CPC were presented as time-based concentration variations 

of a selected particle size with concentrations in normalized particles/ cm3 (dN/dlogDp). 

Particle sizing with the DMS500 

A second instrument used in Phase 2 to measure the size and number distributions of PM 

was a differential mobility spectrometer, DMS500 (Figure 15). The DMS500 was 

directly connected to the secondary dilution tunnel and was used to sample at a point 

close to the standard 70mm filter of the laboratory. Only primary dilution in the full-scale 

CVS tunnel was employed. Secondary dilution was not needed in the tests because the 

filter face temperature remained below 52o

C with just primary dilution. The working 

principle of the DMS500 is that it draws sample flow from the dilution tunnel containing 

aerosols/ particles. It is capable of measuring 41 particle size bins (3.16 nm – 1000 nm) 

as a continuous number count at a maximum frequency of 10Hz. The size bins start at a 

diameter of 3.16 nm and increase in the geometric ratio of 1.15 for each next size bin up 

to the end limit of 1000 nm. The impactor at the inlet removes particles greater than 1000 

nm and then the particles are charged by a corona charger. The charging of the particles 

is argued to depend only on size and not on material composition. The dilute exhaust then 

flows as a uniform laminar sheath through an annular geometry between the inner and 

outer electrodes, as shown in Figure 15, and the charged particles are carried in this dilute 

exhaust flow. The particles are then deflected towards grounded electrometer rings by 

their repulsion from a central high voltage rod. Their landing position on the electrometer 

rings is a function of the particle’s charge and momentum. The particles give up their 

charge to the electrometer amplifiers through the rings and the resulting currents are 

output as particle number and size distribution through the user interface. There are 

40 
studies showing the good accuracy of the DMS500 when compared with the SMPS and 

ELPI7

. 

Figure 15: Working principle of the DMS5008. 

Micro-Orifice Uniform Deposit Impactor (MOUDI) 

WVU used the Micro-Orifice Uniform Deposit Impactor (MOUDI) for gravimetric 

analysis of size-segregated PM0.1 emissions from 10 vehicles (E55CRC-2 – E55CRC-11) 

in Phase 1. The MOUDI, MSP Model 110 is a cascade impactor that classifies particles 

by their aerodynamic diameter in the range of 18 μm to 0.056 μm. Model 110 has ten 

stages with nominal 50% efficiency curve aerodynamic diameters of 0.056, 0.100, 0.180, 

0.320, 0.560, 1.0, 1.8, 3.2, 5.6, 10 and 18.0 μm. The MOUDI moderates the pressure 

drop needed to size submicron aerosols by using nozzles of very small diameter (2000 

nozzles of 52 μm in diameter in the final stage). It operates at a rate of 30 lpm. The flow 

rate is monitored by measuring the pressure drop between the first and the fifth stage with 

a differential pressure gage. The differential pressure was adjusted by a needle valve to a 

pre-calibrated pressure drop corresponding to a flow rate of 30 lpm. The advantage that 

the MOUDI has over other cascade type impactors is its ability to collect ultra fine 

particles with a moderate pressure drop and a uniform deposit. 

Samples from the MOUDI were collected on greased aluminum substrates and one 37 

mm Gelman Sciences TX40 after filter (for PM size fraction less than 0.056 μm). 

41 
Gelman Sciences 47 mm Analyslides were used for transport and storage of the 

substrates. Several researchers have espoused the necessity of applying a thin layer of 

grease to the substrate surface in order to minimize particle bounce (Baron and Willeke, 

1993; Marple et al., 1991). According to the majority of researchers, particle bounce is 

not an important issue in diesel particulate matter sampling. This claim was found to be 

in error by the Principal Investigators in an NREL-funded study (Gautam et al., 2002). 

Particle bounce is a major problem in diesel particulate matter sampling. Upon impact, 

some of the particles may bounce off the substrates and get re-entrained in the sample 

stream where they will pass to successive stages. This will distort the size distribution 

toward the smaller diameter regions, with no definitive method to predict or correct for 

this phenomenon. Substrates, used in this study were greased by Ms. Sue Stine, who had 

formerly worked for the US Bureau of Mines with Dr. Bruce Cantrell, and later for MSP, 

Inc. (manufacturer of the MOUDI). 

Cyclones 

Size-selective cyclone samplers (URG Model 2000-30 EA, 28.3 lpm, 50dae=10μm) were 

used to collect samples of PM10 of exhaust PM. The PM10 cyclone is an inertial particle 

separator that uses centrifugal force to remove heavier particles from a gas stream (>10 

μm and >2.5 μm, respectively). The diluted exhaust sample enters the cyclone 

tangentially, and is drawn through the cyclone body and the in-line filter by a vacuum 

pump. Maintenance of this exact flow rate can be difficult if the conditions at which the 

sample is being collected are not near standard. Cyclone use in a dilution tunnel requires 

a feedback control system to adjust the flow to account for variations in temperature and 

pressure. This signal is used to control a mass flow rate controller that will be 

responsible for maintaining the required constant actual flow rate. 

DRI used a Model Bendix-Unico 240 PM2.5 cyclone to draw dilute exhaust samples from 

WVU’s dilution tunnel into the DRI’s residence time dilution chamber. The cyclones 

were an integral part of the residence time chamber. The cyclone in the DRI residence 

time chamber operated at a volumetric flow rate of 113 liters/minute. 

Unregulated Emissions 

WVU and DRI (subcontractor to WVU) were jointly responsible for unregulated 

emissions measurement, and WVU also provided support for Dr. Kim Prather’s Aerosol 

Time-of-Flight Mass Spectrometer (ATOFMS) data collection. ATOFMS data are not 

discussed in this final report. Listed below are the specific tasks/activities conducted by 

WVU and DRI. 

42 
In addition to the gaseous sampling probes and a secondary dilution tunnel, WVU 

installed the following on the primary dilution tunnel: 

1. PM10 cyclone with TX40 filters for gravimetric analysis (PM2.5 sampling was 

conducted by DRI using the DRI residence time chamber). 

2. Micro-Orifice Uniform Deposit Impactor (MOUDI) probe for gravimetric 

analysis of size-selective PM0.1 samples. Greased aluminum substrates were 

employed for the purpose (for E55CRC-2 to E55CRC-11). 

3. Probe for DRI’s residence time dilution chamber. 

4. Probe for Dr. Kim Prather’s ATOFMS sampling in Phase 1. 

Samples were collected by WVU using DRI’s residence time dilution chamber (with 

dilution) for the first two runs (1773-2 and 1773-3) of E55CRC-01. These runs are not 

considered for the study since the filters and other media did not collect sufficient 

quantity of samples. For all subsequent runs in Phase 1, and for the rest of the study (6 

vehicles in Phase 2), the DRI’s residence time dilution chamber was used without any 

secondary dilution to increase the captured mass. 

Tunnel blanks and tunnel backgrounds were also collected, as listed in the Test Sequence, 

for the three overlap vehicles. 

1. Volatile organic compounds (VOC) – Canisters; field GC 

2. Methane - Canisters 

3. Semi-volatile organic compounds (SVOC) – PUF/XAD and TIGF filters 

4. SVOC, low molecular weight compounds – Tenax tubes 

5. Nitro-PAHs – PUF/XAD and TIGF filters 

6. Carbonyls – DNPH cartridges 

7. Nitrosamines - Thermosorb cartridges 

8. PM soluble organic fraction (SOF): organic compounds – TIGF filters 

9. Elemental analysis and gravimetric analysis (PM2.5) – TIGF filters 

10. Ammonium and Ions (Nitrate, Nitrite, Chloride, Sulfate) – Quartz filters 

11. Elemental Carbon/Organic Carbon (EC/OC) – Quartz filters 

12. PM2.5 fraction for gravimetric analysis 

WVU collected the PM10 fraction using a cyclone for all 25 vehicles in Phase 1, and 6 

‘speciation vehicles’ in Phase 2. The PM0.1 fraction was sampled in Phase 1 using the 

MOUDI for E55CRC-2 to E55CRC-11 only. 

Chemical speciation samples were collected by DRI, using the residence time dilution 

chamber. DRI used a Model Bendix-Unico 240 PM2.5 cyclone to draw dilute exhaust 

samples from WVU’s dilution tunnel into the DRI’s residence time dilution chamber. 

The cyclones were an integral part of the residence time chamber. The cyclone in the DRI 

residence time chamber operated at a volumetric flow rate of 113 lpm (4 cfm). However, 

there was no additional dilution performed within the DRI chamber. The list of chemical 

compounds analyzed and the media used to collect them are given below: 

43 
Details of the sample collection and the analytical procedures followed by DRI are 

provided in Appendix G. 

Speciation Fleet and Approach 

The sampling of non-regulated species occurred at the same time that regulated species 

were sampled. Five HHDDT with a Gross Vehicle Weight Rating (GVWR) of 80,000 

lbs. were selected specifically for non-regulated sampling. These were E55CRC-39, 

E55CRC-40, E55CRC-42, E55CRC-43 and E55CRC-44. A sixth vehicle, E55CRC-41 

was a MHDT and hence cannot be used for comparison purposes directly with the 

HHDDT in this study. The details of the test vehicles, engines, model years and the test 

fuel used is given below in Table 12. 

Table 12: Test Vehicle Details 

Vehicle ID Vehicle 

Manufacturer 

Vehicle 

Model 

Year 

Engine 

Manufacturer 

Engine 

Model 

Engine 

Model 

Year 

Primary 

Fuel 

E55CRC- 39 Volvo 2004 Cummins ISX 530 2004 CARB 

E55CRC- 40 Freightliner 2004 Detroit Diesel Series 60 2003 CARB 

E55CRC- 41 Ford 1998 Cummins B5.9 1997 CARB 

E55CRC- 42 Freightliner 2000 Caterpillar 3406 1999 CARB 

E55CRC- 43 Peterbilt 1995 Detroit Diesel Series 60 1994 CARB 

E55CRC- 44 Volvo 1989 Caterpillar 3406 1989 CARB 

No aftertreatment devices were used on any vehicle. The vehicles were tested in an “as 

received tank fuel” condition in the same way as for regulated emissions characterization. 

Fuel samples for every vehicle were collected at the end of the test period and were sent 

for chemical analysis to Core Laboratories for analysis of cetane number, total sulfur 

content, aromatic content and viscosity. Another sample of the fuel was sent to DRI for 

analysis of inorganic and organic compounds. Oil samples were collected for every 

vehicle and were sent to oil sciences laboratory for 27-point analysis and sulfur content. 

Another sample of the oil was sent to DRI for organic and inorganic analysis. 

This non-regulated emissions study employed the same test schedules that were used for 

the regulated emissions measurement. 

The Idle mode was extended to run three times longer than the normal Idle mode to 

facilitate sufficient sample collection on the speciation media. No speciation or particle 

sizing data were recorded for the Creep mode. The Transient was run normally for 688 

seconds. The Cruise mode was run normally for 2083 seconds. Chemical speciation and 

particle sizing data were recorded for the Idle, Transient, Cruise and High-speed Cruise 

Modes. 

Each mode was repeated twice for every vehicle. Similar multiple modes were 

composited by DRI on the same media to ensure sufficient sample collection. The SMPS 

operated in a full-scan mode during the HHDDT schedule. For the Transient Mode, the 

SMPS was locked onto a particle size of interest and concentration variation for that 

44 
mode was measured. Particle sizes were selected based on the steady state size 

distribution. A steady state run at 40 kph (25 mph) mode, not required for regulated 

emissions testing, was executed prior to any other tests for the sole purpose of obtaining a 

full particle size distribution by the SMPS. The steady state speed of 40 kph (25 mph) 

was selected based on the average speed of the transient cycle. The DMS500 was 

operated during the modes because it was not restricted to steady-state measurements. 

45 
QUALITY ASSURANCE AND QUALITY CONTROL 

The WVU Transportable Laboratory (TransLab) evaluated the emissions from vehicles 

operating in Southern California fueled with diesel or gasoline between August 2001 and 

May 2005. Testing was conducted in Riverside, CA. The independent Quality Assurance 

Quality Control (QA/QC) review of the regulated emissions is summarized below. 

The procedure used in reviewing the data involved four levels of checks. First, the field 

engineer would make an assessment of the quality of the data as it was generated. If a 

test was deemed to be invalid, the field engineer would mark that test as being invalid, 

and provide the reason(s) why the test was invalid, and a new test would be run in its 

place. Additionally, if a test was performed with an atypical result, but there were no 

known problems, the field engineer would annotate the dataset in which this occurred and 

would list potential reasons for the result. For example, if the vehicle was underpowered 

and could not meet the desired target distance then this comment would be added to the 

test record. At the end of the test day, the field engineer electronically transferred the 

data to the project engineer at WVU in Morgantown, WV. 

The second level of assessment of the data quality was performed at WVU by the project 

engineer assigned to maintain the data. The project engineer received the data collected 

the previous day and reviewed the dataset to insure that the correct vehicle/engine model, 

test weights, and test cycles were performed. In instances when there were problems or 

when atypical results were obtained, the field engineer would interact with the project 

engineer during testing via email and/or phone conservations to make an assessment of 

the actions, if any, to take. Additionally, the project engineer would review the integrated 

mass emissions data and the pertinent analog and digital signals required to calculate the 

emissions for potential problems. The project engineer maintained a database of the 

results in tabular and graphical format to be able to identify tampered and or malmaintained (T/M) engines and or vehicles based on criterion developed during this 

project. If a potential T/M vehicle was identified, this information was passed on to the 

Principal Investigators, and this information was then communicated to the sponsors. If a 

problem was identified with the data by the project engineer, then the project engineer 

would interact with the field engineer to rectify the problem. 

The third level of assessment was done by the Principal Investigators. The Principal 

Investigators examined the data and provided feedback to the project engineer of 

potential problems, who was separated from the data gathering process. 

The fourth level of data quality assessment was performed by the QA/QC officer. The 

QA/QC officer received the integrated mass emissions data in the form of single page 

short reports from the project engineer in hardcopy or electronic (Microsoft Word) 

format. Short reports are presented in Appendix K. The QA/QC officer would, at times, 

examine raw and processed data with the project engineer as a spot check throughout this 

test program. The test, vehicle, and emissions data summarized in each short report were 

reviewed on a per test basis and per vehicle basis for inconsistencies in the information 

46 
and emissions data. Inconsistencies in the information were brought to the project 

engineer’s attention and corrected. These corrections included misspellings, incorrect 

vehicle description, incorrect engine description, lack of comments, and other minor 

corrections. These corrections are not summarized in the table below. Questions, 

concerns, and inconsistencies in the emissions data that were directed to the project 

engineer are summarized in the table below. The corrective action taken is also listed. 

The majority of the inconsistencies in the emissions data can be attributed to trying to 

measure very low emissions levels (such as low engine power Idle and Creep modes) and 

higher level emissions (high engine power transient and cruise modes) with one set of 

emissions analyzers and one calibration range. There was a two order of magnitude 

difference in the emissions concentration levels between the low and high engine power 

modes, so that low power modes to have a much greater variability in this data. 

There were difficulties in comparing the results from two different NOx analyzers during 

the first half of the test program. The difference in the two NOx analyzers was addressed 

throughout this test program by improving the test procedure to adjust the second NOx 

analyzer flow and the changing of NOx analyzers to newer technology. 

47 
RESULTS AND DISCUSSION, REGULATED SPECIES 

HHDT Data Gathered 

Test Runs 

Each execution of a cycle or mode was assigned a sequence number and a run number. 

Appendix J presents a listing of sequence and run numbers, with the corresponding name 

of the cycle, vehicle number and test weight. Some sequence and run numbers are 

omitted in Table 3 because they are associated with background tests or with rejected 

runs. In Table 3 the test modes or cycles are designated by the actual file names used. 

“Test D” corresponds to the UDDS, trans3 and cruise3 refer to the three point smoothed 

versions of the Transient and Cruise Modes that are customarily used. Some modes were 

lengthened by being repeated to collect sufficient PM mass during the mode. Idle32 

refers to a double length idle (1,800 seconds instead of 900 seconds), and creep34 refers 

to four repeats of a creep run as a single mode. Table 3 corresponds to the sequence and 

run numbers in the short reports appearing in Appendix K. MHDT are shown with 50% 

and 75% test weights. The actual weights used appear in Appendix J. 

Data Gathered 

The cycle or mode-averaged data, in units of g/mile (except for idle, which is in timespecific units) are all presented in Appendix K in the form of “short reports.” These data 

have also been translated into graphical representations in Appendix H. Data have been 

gathered into summary tables in Appendix L. The full database containing continuous 

vehicle operating data and gaseous emissions rates has been made available to the 

sponsors separately in electronic form. 

Discussion of individual truck emissions within the body of this report emphasizes two 

species, NOx and PM, since NOx and PM data are assumed to be of greatest interest for 

truck operation. However, CO and HC have also been presented with respect to select 

cycles below and for all cycles in the appendices. The ARB cycles (Idle, Creep, Trans, 

Cruise, and HHDDT_S) demonstrate a variety of driving conditions. Additional, more 

comprehensive plots of the data appear in Appendix M. Some vehicles were “speed 

limited” to the point where they were unable to follow the schedule trace and were not 

tested for the HHDDT_S. HHDDT in Phase 1 were not exercised through the 

HHDDT_S. 

Figure 16 presents the NOx emissions for all of the HHDDT on the Idle mode of the 

HHDDT schedule. The range of years appearing in Figure 16 corresponds to the CRC 

grouping of the years of engine certification. The number below indicates the number of 

vehicles tested in that MY range for which data are included in the chart. The 1998 

vehicles show the highest NOx emissions of all MY bins. Later MY trucks produce 

higher NOx than early MY trucks because the injection timing may be advanced on later 

model trucks to reduce white smoking. The reader is cautioned that small number counts 

of vehicles in some MY bins may cause the program data in some represent the whole 

48 
California fleet faithful. This is especially true if one of the vehicles in the group is an 

outlier, or high emitter. 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

g/mile g/mile 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

2 2 2 3 5 7 6 10 3 11 

Figure 16: NOx emissions for the Idle Mode, in units of g/minute. 

100.0 

90.0 

80.0 

70.0 

60.0 

50.0 

40.0 

30.0 

20.0 

10.0 

0.0 

Pre1975 1975-

1976 

1977-

1979 

1980-

1983 

1984-

1986 

1987-

1990 

1991-

1993 

1994-

1997 

1998 1999-

2002 

2003+ 

2 2 2 3 6 7 6 10 3 11 5 

Figure 17: NOx emissions for the Creep mode (56,000 lbs.). 

49 

6 
Figure 17 shows NOx emissions for all HHDDT trucks operated through the Creep mode 

at 56,000 lbs. test weight. This mode is primarily low speed with repeated upward and 

downward speed ramps. The small distance traveled and high idle content lead to high 

distance-specific emissions values. Results are less variable over the MY bins than for 

idle, but idle and low load injection timing advance is also the most likely cause for the 

high NOx emissions over the 1987 to 2002 period. 

Figure 18 shows NOx emissions for all HHDDT trucks operated through the Transient 

mode at 56,000 lbs. test weight. The Transient mode represents typical urban driving 

activity. Figure 18 shows that the NOx emissions for 1998 were higher than for 

neighboring MY bins, but the highest NOx arose from the oldest vehicles. The 1975 to 

1976 MY bin was the highest at 47 g/mile. This was primarily due to their being only 

two sample vehicles, one of which emitted 60 g/mile while the other was 34 g/mile. The 

1980 to 1983 MY bin contained vehicles consistently emitting high NOx. The emissions 

of NOx prior to 2002 were all higher than 20 g/mile. The NOx emissions of the five 2003 

and newer MY vehicles (equipped with exhaust gas recirculation for Cummins and 

Detroit Diesel, or bridging/ACERT technology for Caterpillar) differ in that they 

averaged less than 17 g/mile. 

50.0 

45.0 

40.0 

35.0 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

g/mile 

Pre1975 1975-

1976 

1977-

1979 

1980-

1983 

1984-

1986 

1987-

1990 

1991-

1993 

1994-

1997 

1998 1999-

2002 

2003+ 

2 2 3 5 7 13 13 3 12 5 

Figure 18: NOx emissions for the Transient mode (56,000 lbs.). One of the vehicles in 

the 1975-1976 MY bin emitted NOx at 60 g/mile. 

50 

2 
Figure 19 shows NOx emissions for all HHDDT trucks operated through the Cruise mode 

at 56,000 lbs. test weight. Figure 19 shows that the NOx emissions for 1998 were higher 

than all but the 1975-1976 group of trucks. The 1998 trucks were also relatively higher 

than they were for the Transient mode. This suggests that off-cycle injection timing was 

enacted more on the Cruise mode than the Transient mode, which would be expected. 

This issue is discussed in more detail in the section on T&M and reflash. The NOx 

emissions of the five 2003 and newer MY engines (equipped with exhaust gas 

recirculation or bridging/ACERT technology) differ in that they averaged to about 9 

g/mile. 

Prior studies with fewer HHDDT1,10,11,12 and earlier reports in the E-55/59 program have 

suggested that NOx did not decline with MY. Figure 19 shows a pattern of high NOx on 

the oldest trucks, as well as trucks in the 90’s that have off-cycle injection timing 

advance, with a decline in NOx for the latest MY trucks. However, there is no clear trend 

in NOx with respect to MY from 1977 to 1997 for trucks exercised through the Cruise 

mode at 56,000 lbs. test weight. 

40.0 

35.0 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

Pre1975 1975-

1976 

1977-

1979 

1980-

1983 

1984-

1986 

1987-

1990 

1991-

1993 

1994-

1997 

1998 1999-

2002 

2003+ 

2 2 2 3 5 7 6 10 3 12 5 

Figure 19: NOx emissions for the Cruise mode (56,000 lbs.). One 1998 vehicle 

(E55CRC-10) was identified as a high NOx emitter in Phase 1. 

Figure 20 shows NOx emissions for the HHDDT_S mode at 56,000 lbs. test weight. This 

sample of trucks excludes the Phase 1 HHDDT because they were not tested on the 

51 

g/mile 
HHDDT_S. This mode has a high content of near-steady high-speed freeway operation. 

A 2003 MY truck exhibited lowest NOx, at 8.05 g/mile. The 1969, 1975 and 1998 engine 

years exhibited the highest NOx at approximately 29, 56, and 22 g/mile respectively. A 

1975 Cummins-powered truck had the highest with 56 g/mile, as the lone truck in the 

1975-1976 category that completed the HHDDT_S mode. 

60.0 

50.0 

40.0 

30.0 

20.0 

10.0 

0.0 

Pre1975 1975-

1976 

1980-

1983 

1984-

1986 

1987-

1990 

1991-

1993 

1994-

1997 

1998 1999-

2002 

2003+ 2003+ 2003+ 

1 1 1 2 2 2 6 1 6 2 2 

g/mile 

Figure 20: NOx emissions for HHDDT_S mode (56,000 lbs.). The high value for the 

1975-1976 MY bin is due to a single truck with high NOx emissions. 

Figure 21 shows the NOx emissions for the UDDS. The distribution of emission levels of 

this urban driving cycle is similar to that found in the Transient mode of Figure 18 above. 

Figure 22 shows the PM emissions for the Idle mode. E55CRC-37 was tested in this 

mode only since it could not operate on the dynamometer due to traction control 

technology. For this reason there is an additional 2003+ data point on the Idle graph 

(Figure 22) relative to the active modes. Some MY bins were high due to outlying 

performance by individual vehicles. For example, E55CRC-45, discussed in the T&M 

section, was a prodigious emitter of both PM and HC and biased the data for the 1991-

1993 MY group. PM was lowest in the 2003 and later MY group. 

52 

6 
45.0 

40.0 

35.0 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

Pre1975 

2 

1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1976 1979 1983 1986 1990 1993 1997 2002 

2 2 3 5 7 6 10 3 11 

g/mile g/mile 

Figure 21: NOx emissions for UDDS mode (56,000 lbs.). 

0.18 

0.16 

0.14 

0.12 

0.10 

0.08 

0.06 

0.04 

0.02 

0.00 

Pre1975 

2 

1975-

1976 

2 

1977-

1979 

2 

1980-

1983 

3 

1984-

1986 

5 

1987-

1990 

7 

1991-

1993 

6 

1994-

1997 

10 

1998 

3 

1999-

2002 

11 

2003+ 

6 

Figure 22: PM emissions for Idle Mode. Truck E55CRC-45, in the 1991-1993 MY 

bin, was a prodigious emitter and raised the average value for that bin substantially. 

53 

5 
Figure 23 shows PM emissions for HHDDT for the Creep mode. The two highest bins 

for the Creep mode are the same as for the Idle mode. The 2003+ group has a 

significantly lower output than even the second lowest group (1998). g/mile 

18.0 

16.0 

14.0 

12.0 

10.0 

8.0 

6.0 

4.0 

2.0 

0.0 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

2 2 2 3 6 7 6 10 3 11 5 

Figure 23: PM emissions for Creep mode (56,000 lbs.). One vehicle in the 1991-1993 

MY bin was a very high emitter of both PM and HC at light load. 

Figure 24 shows PM emissions for all HHDDT trucks operated through the Transient 

mode at 56,000 lbs. test weight. E55CRC-45, a 1993 Cummins-powered tractor 

demonstrated significantly higher PM emissions than the other test vehicles at low load, 

but E55CRC-45 biased the data far less in the Transient mode. In the highest emitting 

group, E55CRC-16 emitted 15 grams per mile of PM and the other vehicle in the 1977-

1979 group emitted 2 grams per mile. E55CRC-16 is discussed in detail in the T & M 

section. There is a general downward trend in PM emissions on the Transient mode with 

respect to MY. 

Figure 25 shows the PM emissions for the Cruise mode. Unlike in most other modes, the 

2003+ group does not have the lowest emissions. E55CRC-16, a 1979 Caterpillarpowered HHDDT, had the highest PM emissions with 16 g/mile, and led to the high 

value for the 1977 to 1979 MY group. Even without this MY group, it is evident that PM 

has declined over three decades for cruising operation. PM emissions after the 

introduction of electronic engines in the 1991-1993 period are lower than the emissions 

from earlier mechanically controlled engines. This can be ascribed to improved fuel and 

boost management, and higher injection pressures for later MY regulations. 

54 
g/mile 

9.0 

8.0 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

2 2 2 3 5 7 13 13 3 12 

Figure 24: PM Emissions for the Transient mode (56,000 lbs.). Truck E55CRC-16, a 

high emitter, caused the high average in the 1977-1979 MY bin 

g/mile 

9.0 

8.0 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre1975 

2 

1975-

1976 

2 

1977-

1979 

2 

1980-

1983 

3 

1984-

1986 

5 

1987-

1990 

7 

1991-

1993 

6 

1994-

1997 

10 

1998 

3 

1999-

2002 

12 

2003+ 

5 

Figure 25: PM emissions for the Cruise mode (56,000 lbs.). E55CRC-16 contributed 

to the one very high MY bin average. 

55 

5 
Figure 26 shows PM emissions for all HHDDT trucks operated through the HHDDT_S 

mode at 56,000 lbs. test weight. E55CRC-27 was the first vehicle tested using the 

HHDDT_S Mode. E55CRC-69 was unable to attain sufficient speed to provide 

meaningful data in the HHDDT_S mode. It was governed to 55 mph maximum speed. 

The first three groups in Figure 26 had only one vehicle in each group, each of which had 

significantly higher emissions than the newer vehicles. There appears to have been a step 

change in PM emissions beginning with the 1991-1993 group. E55CRC-29, a 1999 

Cummins, escalated the average for the 1999-2002 group by emitting 2.52 g/mile of PM, 

a value more than twice as high as for any other vehicle in the group. 

4.5 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0

Pre- 1975- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 2003+ 2003+ 

1975 1976 1983 1986 1990 1993 1997 2002 

1 1 1 2 2 2 6 1 6 2 2 

g/mile 

Figure 26: PM emissions for HHDDT_S mode (56,000 lbs.). Four MY groups show 

data from only one vehicle. 

Figure 27 shows the PM emissions for the UDDS. As was the case with the NOx 

emissions, the UDDS and Transient modes show a similar distribution pattern. 

Figure 28 shows the CO emissions for the Trans3 Mode. While there were a handful of 

vehicles with emissions higher than other trucks in the MY bin, the highest was 

E55CRC-23 (1983 Cummins) with 40 g/mile. Also, the 2003 Detroit Diesel engine of 

E55CRC-44 was significantly (two to four times) higher in both CO and PM than the 

other four vehicles in the 2003+ group. 

56 

6 
g/mile g/mile 

8.0 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

2 2 2 3 5 7 6 10 3 11 5 

Figure 27: PM emissions for UDDS mode (56,000 lbs.). 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

2 2 2 3 5 7 13 13 3 12 5 

Figure 28: CO emissions for Transient mode (56,000 lbs.). 

57 
Figure 29 shows the CO emissions for the Cruise mode. In sympathy with the data for 

the Transient mode, E55CRC-23 with its 1983 Cummins was nearly the highest emitter. 

E55CRC-20 with a 1992 Detroit Diesel engine also had about 14 g/mile of CO emissions. 

If it were not for the 2003 Detroit Diesel engine of E55CRC-34, the 2003+ group would 

have represented an even more dramatic drop from previous model years. 

9.0 

8.0 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre1975 1975-

1976 

1977-

1979 

1980-

1983 

1984-

1986 

1987-

1990 

1991-

1993 

1994-

1997 

1998 1999-

2002 

2003+ 

2 2 2 3 5 7 6 10 3 12 

g/mile 

Figure 29: CO emissions for Cruise mode (56,000 lbs.). 

HC emissions from vehicles built over the last decade are lower than from older vehicles 

in the older vehicles in the test fleet. Figure 30 shows the HC emissions for the Transient 

mode. E55CRC-45 had a 1993 Cummins engine. It emitted the highest level of HC at 

5.43 g/mile. E55CRC-45 was a high emitter of both PM and HC at light loads, and has 

been discussed in the T & M section. The 1994 Cummins of E55CRC-60 emitted 4.18 

g/mile. Both of these trucks showed far higher emissions than were measured from the 

other vehicles in each of their respective MY bins. 

Figure 31 shows the HC emissions for the Cruise mode. E55CRC-45 (1993 Cummins) 

again ranked as one of the top HC emitting vehicles, and biased the 1991-1993 MY bin. 

The five most recent MY bins show lower emissions, on average than earlier MY bins, 

but there is no clear, monotonic, pattern to HC reduction with respect to MY. 

Additional plots showing the HHDDT emissions at test weights of 30,000 and 66,000 lbs. 

are available in Appendix M. 

58 

5 
g/mile g/mile 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002

2 2 2 3 5 7 13 13 3 12 5

Figure 30: HC emissions for Transient mode (56,000 lbs.). 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002

2 2 2 3 5 7 6 10 3 12 5

Figure 31: HC emissions for Cruise mode (56,000 lbs.). 

59 
MHDT Data Discussion 

This section discusses results of the testing of the MHDT. The MHDT Schedule includes 

a lower speed transient mode (MHDTLO), a higher speed transient mode (MHDTHI), a 

cruise mode (MHDTCR), and the HHDDT_S. Figure 32 shows emissions from the 

AC5080, which was also used. Figure 33 presents NOx emissions for the Lower Speed 

Transient mode from the MHDT. In these, and all other figures in this section, ‘laden’ 

refers to 75% of the gross vehicle weight rating (GVWR) and ‘unladen’ refers to 50% of 

the GVWR. NOx emissions from these MHDT are similar to those of the HHDDT 

transient mode. 

E55CRC-57, in the 1999-2002 group, showed an unusually high unladen NOx emissions 

value. This was ascribed to a failed temperature sensor, which caused a limp-home 

mode. E55CRC-57 has been discussed in detail in the T & M section. 

The three early model gasoline engines yielded NOx emissions on the Lower Speed 

Transient mode that were similar in emissions from the diesel vehicles, but the one newer 

gasoline vehicle, E55CRC-53, produced the lowest NOx relative to other categories of 

truck. 

18.0 

16.0 

14.0 

12.0 

10.0 

8.0 

6.0 

4.0 

2.0 

0.0 

Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Unladen 

Laden 

g/mile 

Figure 32: NOx emissions for AC5080 (both laden and unladen). Gasoline-fueled 

vehicles are separated from diesel-fueled vehicles for comparison. 

60 

3 
g/mile 

35.0 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

Pre-1975 1984- 1987- 1987- 1991- 1991- 1994- 1999- 1999-

1986 1990 1990 1993 1993 1997 2002 2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Unladen 

Laden 

Figure 33: NOx emissions for the Lower Speed Transient mode (both laden and 

unladen). 

Figure 34 shows that the NOx emissions for the Higher Speed Transient mode were 

consistently lower than for the Lower Speed Transient Mode. As in the previous mode, 

E55CRC-53, with a gasoline engine, produced the lowest NOx emissions at fewer than 4 

g/mile. The older gasoline vehicle, E55CRC-54, emitted NOx at a level characteristic of 

the diesel trucks. From Figure 32 to Figure 47 it is important to realize that varying test 

weights from truck to truck influences distance-specific emission levels. 

As seen in Figure 35, NOx emissions during the MHDT Cruise mode were slightly lower 

than for either of the Transient modes and were close to those of the high-speed cruise 

(HHDDT_S) shown in Figure 36. The older gasoline fueled trucks on average emitted 

NOx at a higher rate than the diesel fleet. Note that Figure 36 is for a small subset of 

vehicles. Figure 37 shows NOx on the UDDS for MHDT. 

61 

5 
Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 3 

Unladen 

Laden 

Figure 34: NOx emissions for the Higher Speed Transient mode (both laden and 

unladen). 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

g/mile g/mile 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

Unladen 

Laden 

Pre-1975 1984- 1987- 1987- 1991- 1991- 1994- 1999- 1999-

1986 1990 1990 1993 1993 1997 2002 2002 

1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Figure 35: NOx emissions for the MHDT Cruise mode (both laden and unladen). 

62 

1 3 
0.0 

5.0 

10.0 

15.0 

20.0 

25.0 

30.0 

35.0 

1984-1986 1987-1990 1987-1990 1991-1993 1991-1993 1994-1997 1999-2002 

1 1 1 (gas) 2 1 (gas) 3 2 

g/mile 

Unladen 

Laden 

Figure 36: NOx emissions for the HHDDT_S mode (both laden and unladen). 

20.0 

18.0 

16.0 

14.0 

12.0 

10.0 

8.0 

6.0 

4.0 

2.0 

0.0 

Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 3 

Unladen 

Laden 

g/mile 

Figure 37: NOx emissions for the UDDS mode (both laden and unladen). 

63 
3.0 

Figure 38, Figure 39, Figure 40, Figure 41, and Figure 42 show PM emissions for the 

AC5080, MHDT Lower and Higher Speed transients, the MHDT Cruise mode, and the 

HHDDT_S mode. As expected, PM values from the gasoline trucks were consistently 

well below those of the diesel vehicles. The influence of test weight (laden vs. unladen) 

on PM was noticeably greater than for NOx. For the limited number of trucks tested, one 

may conclude that PM levels have not changed from MY 1991 to MY 2002. 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Unladen 

Laden 

g/mile 

Figure 38: PM emissions for the AC5080 mode (both laden and unladen). 

For the HHDDT_S (Figure 42), only selected trucks were used from the MHDT fleet, 

leading to relatively higher MY 1991-1993 group emissions. E55CRC-76 contributed to 

the high emissions in the 1991-1993 MY group. 

Figure 43 shows emissions of PM for the UDDS. The four gasoline vehicles emitted, on 

average, an order of magnitude lower PM than the diesel fleet. 

Figure 44 and Figure 45 present CO emissions data for the MHDT on the Higher Speed 

Transient and MHDT Cruise modes. In contrast to their PM contribution, CO from the 

gasoline vehicles was substantially higher than from the diesel vehicles. 

64 

3 
g/mile 

5.0 

4.5 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 5 

Unladen 

Laden 

Figure 39: PM emissions for the Lower Speed Transient mode (both laden and 

unladen). 

3.5 

Unladen 

3.0 Laden 

2.5 

g/mile 

2.0 

1.5 

1.0 

0.5 

0.0 

Pre-1975 

1 

1984-

1986 

1 

1987-

1990 

2 

1987-

1990 

1 (gas) 

1991-

1993 

2 

1991-

1993 

2 (gas) 

1994-

1997 

5 

1999-

2002 

1 (gas) 

1999-

2002 

3 

Figure 40: PM emissions for the Higher Speed Transient mode (both laden and 

unladen). 

65 
8.0 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre-1975 1984- 1987- 1987- 1991- 1991- 1994- 1999- 1999-

1986 1990 1990 1993 1993 1997 2002 2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Unladen 

Laden 

Figure 41: PM emissions for the Cruise mode (both laden and unladen). 

g/mile 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

1984-1986 1987-1990 1987-1990 1991-1993 1991-1993 1994-1997 1999-2002 

1 1 1 (gas) 2 1 (gas) 3 2 

g/mile 

Unladen 

Laden 

Figure 42: PM emissions for the HHDDT_S mode (both laden and unladen). 

66 

3 
g/mile g/mile 

4.5 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 3 

Unladen 

Laden 

Figure 43: PM emissions for UDDS mode (both laden and unladen). 

200.0 

180.0 

160.0 

140.0 

120.0 

100.0 

80.0 

60.0 

40.0 

20.0 

0.0 

Pre-1975 1984- 1987- 1987- 1991- 1991- 1994- 1999- 1999-

1986 1990 1990 1993 1993 1997 2002 2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Unladen 

Laden 

Figure 44: CO emissions for MHDTHI mode (both laden and unladen). 

67 

3 
g/mile g/mile 

100.0 

90.0 

80.0 

70.0 

60.0 

50.0 

40.0 

30.0 

20.0 

10.0 

0.0 

Unladen 

Laden 

Pre-1975 1984- 1987- 1987- 1991- 1991- 1994- 1999- 1999-

1986 1990 1990 1993 1993 1997 2002 2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 3 

Figure 45: CO emissions for the MHDTCR mode (both laden and unladen). 

14.0 

Pre-1975 1984-

1986 

1987-

1990 

1987-

1990 

1991-

1993 

1991-

1993 

1994-

1997 

1999-

2002 

1999-

2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 3 

Unladen 

12.0 Laden 

10.0 

8.0 

6.0 

4.0 

2.0 

0.0 

Figure 46: HC emissions for MHDTHI mode (both laden and unladen). 

68 
g/mile 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Pre-1975 1984- 1987- 1987- 1991- 1991- 1994- 1999- 1999-

1986 1990 1990 1993 1993 1997 2002 2002 

1 1 2 1 (gas) 2 2 (gas) 5 1 (gas) 

Unladen 

Laden 

Figure 47: HC emissions for MHDTCR mode (both laden and unladen). 

Figure 46 and Figure 47 present HC emissions for the MHDT on the Higher Speed 

Transient and the MHDT Cruise modes. The oldest MHDDT produced substantially 

higher emissions of HC than the remaining MHDDT on the MHDT Cruise mode. The 

newest MHDGT produced no more HC on cruise than the diesel truck of similar MY. 

Additional plots for MHDT emissions on other modes and cycles are presented in 

Appendix M. 

Continuous Data 

All dynamometer speeds and torques, all regulated gaseous emissions, exhaust and tunnel 

temperatures, and TEOM data are available on a continuous basis. These data are 

available to the sponsors separately from this report. Figure 48, Figure 49, and Figure 50 

present examples of continuous NOx, HC and CO emissions from E55CRC-42 on the 

Transient mode at 56,000 lbs. test weight and Figure 51 shows the exhaust temperature of 

this vehicle. 

69 

3 
g/s 

0.4 

0.3 

0.2 

0.1 

0.0 

0 100 200 300 400 500 600 700 

Time (s) 

Figure 48: Example of a continuous NOx emissions plot in g/s for E55CRC-42 

(56,000 lbs.) following the HHDDT Transient Mode. 

0.035 

0.030 

0.025 

0.020 

0 100 200 300 400 500 600 700 

Time (s) 

g/s 

0.015 

0.010 

0.005 

0.000 

Figure 49: Example of a continuous HC emissions plot in g/s for E55CRC-42 

(56,000 lbs.) following the HHDDT Transient Mode. 

70 
g/s 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0.00 

0 100 200 300 400 500 600 700 

Time (s) 

Figure 50: Example of a continuous CO emissions plot in g/s for E55CRC-42 (56,000 

lbs.) following the HHDDT Transient Mode. 

0 

100 

200 

300 

400 

500 

600 

700 

800 

E x h au st T em p eratu re (F ) 

0 100 200 300 400 500 600 700 

Time (s) 

Figure 51: Example of a continuous exhaust temperature reading for E55CRC-42 

(56,000 lbs.) following the Transient mode schedule. 

71 
E55CRC-26 

E55CRC-27 

E55CRC-28 

E55CRC-29 

E55CRC-30 

E55CRC-31 

E55CRC-32 

E55CRC-3 3

E55CRC-34 

E55CRC-35 

E55CRC-36 

E55CRC-38 

HHDDT Effect of Test Weight 

HHDDT data have been provided above only for the 56,000 lbs. test weight, which was 

used for all trucks. Data for fleet subsets tested at 30,000 lbs. and 66,000 lbs. appear in 

Appendix N. Figure 52, Figure 53, Figure 54 and Figure 55 show the effect of test 

weight for Transient and Cruise modes, for PM and NOx, for all trucks that were tested at 

all three weights. NOx rose in all cases as the weight rose from 30,000 to 56,000 lbs., but 

in a few cases, NOx was lower when the weight was increased to 66,000 lbs. This may 

be ascribed to variability in injection timing over the engine map, and to different gear 

selection at the higher weight. 

0.0 

5.0 

10.0 

15.0 

20.0 

25.0 

30.0 

35.0 

40.0 

45.0 

50.0 

g/mile 

30,000 lbs. 

56,000 lbs. 

66,000 lbs. 

Figure 52: Transient mode NOx weight effects 

72 
E55CRC-26 

E55CRC-27 

E55CRC-28 

E55CRC-29 

E55CRC-30 

E55CRC-31 

E55CRC-32 

E55CRC-3 3

E55CRC-34 

E55CRC-35 

E55CRC-36 

E55CRC-38 

E55CRC-26 

E55CRC-27 

E55CRC-28 

E55CRC-29 

E55CRC-30 

E55CRC-31 

E55CRC-32 

E55CRC-3 3

E55CRC-34 

E55CRC-35 

E55CRC-36 

E55CRC-38 

0.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

7.0 

8.0 

g/mile 

30,000 lbs. 

56,000 lbs. 

66,000 lbs. 

Figure 53: Transient mode PM weight effect 

0.0 

5.0 

10.0 

15.0 

20.0 

25.0 

30.0 

35.0 

30,000 lbs. 

56,000 lbs. 

66,000 lbs. 

g/mile 

Figure 54: Cruise mode NOx weight effect 

73 
E55CRC-26 

E55CRC-27 

E55CRC-28 

E55CRC-29 

E55CRC-30 

E55CRC-31 

E55CRC-32 

E55CRC-3 3

E55CRC-34 

E55CRC-35 

E55CRC-36 

E55CRC-38 

For PM, the weight effect was far less clear. No simple conclusions can be presented 

except that PM rose as test weight was raised from 30,000 to 56,000 lbs. for almost all 

cases for the Transient mode. 

3.5 

30,000 lbs. 3.0 56,000 lbs. 

66,000 lbs. 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Figure 55: Cruise mode PM weight effect 

MHDT Effect of Test Weight 

Figure 34 and Figure 35 in the section above provide a partial view of the effect of test 

weight on NOx emissions. While there were substantial truck-to-truck variations, the 

average effect of weight across the MHDT fleet was a rise in NOx of 9% for the Higher 

Speed Transient mode and 8% for the cruise mode as the weight increased from 50 

percent to 75 percent of the GVWR. The research effort to establish the MHDT schedule3 

found, in agreement with the present study, that effect of weight on NOx was smaller than 

previously established for HHDDT. The average effect on PM seen in Figure 40 and 

Figure 41 indicated an increase of 50% for the Higher Speed Transient mode and 47% for 

the MHDT Cruise mode as weight was increased from unladen to laden. g/mile 

74 
COMPARISON OF DATA BETWEEN PHASES 

Data for the same MY bins were compared between phases to assess phase to phase 

repeatability. Figure 56 shows data for CO2 emissions, in units of g/mile, for all HHDDT 

operated through the UDDS at 56,000 lbs. test weight. 

0 

500 

1000 

1500 

2000 

2500 

3000 

3500 

g/mile 

Phase 1 

Phase 1.5 

Phase 2 

Phase 3 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

Figure 56: Variation of HHDDT CO2 emissions by vehicle model year and by phase 

of the program for the UDDS (56,000 lbs.). 

There is little variation in the CO2 emissions values over MY or by phase, because CO2 

values are governed by the engine efficiency and cycle energy demands. (The standard 

deviation of the data below is 302 g/mile, approximately 13 percent of the average.) 

These data build confidence in the repeatability of data between phases, and suggest that 

both the dilution tunnel flowrate calibration and the CO2 analyzer response remained 

consistent between phases. In contrast, Figure 57 shows that CO varied substantially 

within MY group. (The standard deviation of the data in Figure 57 is 8.7 g/mile, or 84% 

of the average.) Since CO is known to be a species that varies widely from truck to truck, 

this suggests that too few vehicles were selected in each phase to form a reliable opinion 

on average CO emissions for each MY bin. NOx emissions are less variable over the fleet 

than CO emissions, as shown in Figure 58. However, Figure 58 still shows variation 

between phases. The NOx data were guaranteed to have reasonable accuracy by 

employing two separate NOx analyzers for most of the program. PM data also varied 

between phases, as shown in Figure 59. (The standard deviation of the data in Figure 59 

75 
is 9.7 g/mile, or 41% of the average.) A correspondence of Figure 57 and Figure 59 show 

a correspondence of high CO and PM by phase in sympathy with one another. Examples 

are the Phase 1.5 data in the 1999-2002 and 2003+ MY bins. One must conclude that the 

fleets in each individual phase were also too small for use in reaching conclusions on CO, 

NOx or PM averages. 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

Figure 57: Variation of HHDDT CO emissions by vehicle model year and by phase 

of the program for the UDDS (56,000 lbs.). 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

g/mile 

Phase 1 

Phase 1.5 

Phase 2 

Phase 3 

76 
0 

10 

20 

30 

40 

50 

60 

g/mile 

Phase 1 

Phase 1.5 

Phase 2 

Phase 3 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

Figure 58: Variation of HHDDT oxides of NOx by vehicle model year and by phase 

of the program for the UDDS (56,000 lbs.). 

0 

1 

2 

3 

4 

5 

6 

7 

8 

g/mile 

Phase 1 

Phase 1.5 

Phase 2 

Phase 3 

Pre- 1975- 1977- 1980- 1984- 1987- 1991- 1994- 1998 1999- 2003+ 

1975 1976 1979 1983 1986 1990 1993 1997 2002 

Figure 59: Variation of PM emissions by vehicle model year and by phase of the 

program for the UDDS (56,000 lbs.). 

77 
RESULTS AND DISCUSSION, NONREGULATED SPECIES 

Semi-Volatile Organic Compounds 

Exhaust Samples 

Table 13 lists PAH, oxy-PAH, nitro-PAH, hopanes, steranes, organic acids and other 

compounds of interest (with their mnemonics) quantified for this study. The minimum 

detection limit (MDL) for PAH, oxy-PAH and other organic compounds was compounddependent, and in general, in the range of 20-50 pg/μl. For nitro-PAH analyzed by 

negative ion CI method, the MDL was in the range of 1pg/μl. 

Table 13: List of Target Analytes in the Particulate and Semi-Volatile Fractions. 

Mnemonic Compound Mnemonic Compound 

Polycyclic Aromatic Hydrocarbons (PAH)and oxy-PAH 

NAPHTH Naphthalene ANTHONE Anthrone 

MNAPH2 2-methylnaphthalene ANRQUONE Anthraquinone 

MNAPH1 1-methylnaphthalene DM36PH 3,6-dimethylphenanthrene 

BIPHEN Biphenyl A_DMPH A-dimethylphenanthrene 

ENAP12 1+2ethylnaphthalene B_DMPH B-dimethylphenanthrene 

DMN267 2,6+2,7-dimethylnaphthalene C_DMPH C-dimethylphenanthrene 

DM1367 1,3+1,6+1,7dimethylnaphth DM17PH 1,7-dimethylphenanthrene 

D14523 1,4+1,5+2,3-dimethylnaphth D_DMPH D-dimethylphenanthrene 

DMN12 1,2-dimethylnaphthalene E_DMPH E-dimethylphenanthrene 

M_2BPH 2-Methylbiphenyl ANTHRA Anthracene 

M_3BPH 3-Methylbiphenyl M_9ANT 9-methylanthracene 

M_4BPH 4-Methylbiphenyl FLUORA Fluoranthene 

DBZFUR Dibenzofuran PYRENE Pyrene 

ATMNAP A-trimethylnaphthalene ANTAL9 9-Anthraaldehyde 

BTMNAP B-trimethylnaphthalene RETENE Retene 

CTMNAP C-trimethylnaphthalene BNTIOP Benzonaphthothiophene 

ETMNAP E-trimethylnaphthalene C1MFLPY 1-MeFl+C-MeFl/Py 

FTMNAP F-trimethylnaphthalene BMPYFL B-MePy/MeFl 

TMI235N 2,3,5+I-trimethylnaphthalene CMPYFL C-MePy/MeFl 

TM245N 2,4,5-trimethylnaphthalene DMPYFL D-MePy/MeFl 

JTMNAP J-trimethylnaphthalene M_4PYR 4-methylpyrene 

TM145N 1,4,5-trimethylnaphthalene M_1PYR 1-methylpyrene 

ACNAPY Acenaphthylene BZCPHEN Benzo(c)phenanthrene 

ACNAPE Acenaphthene BAANTH Benz(a)anthracene 

FLUORE Fluorene M_7BAA 7-methylbenz(a)anthracene 

PHENAN Phenanthrene CHRYSN Chrysene 

A_MFLU A-methylfluorene BZANTHR Benzanthrone 

M_1FLU 1-methylfluorene BAA7_12 Benz(a)anthracene-7,12-dione 

B_MFLU B-methylfluorene CHRY56M 5+6-methylchrysene 

FL9ONE 9-fluorenone BBJKFL Benzo(b+j+k)fluoranthene 

XANONE Xanthone M_7BPY 7-methylbenzo(a)pyrene 

ACQUONE Acenaphthenequinone BEPYRN BeP 

PNAPONE Perinaphthenone PERYLE Perylene 

A_MPHT A-methylphenanthrene BAPYRN BaP 

78
Mnemonic Compound Mnemonic Compound 

M_2PHT 2-methylphenanthrene INCDPY Indeno[123-cd]pyrene 

B_MPHT B-methylphenanthrene BGHIPE Benzo(ghi)perylene 

C_MPHT C-methylphenanthrene DBANTH Dibenzo(ah+ac)anthracene 

M_1PHT 1-methylphenanthrene CORONE Coronene 

Hopanes/Steranes 

STER35 20S-13ß(H),17a(H)-diasterane STER52 20S5a(H),14ß(H),17ß(H)-

stigmastane 

STER36 20R-13ß(H),17a(H)-diasterane HOP13 18a(H),21ß(H)-22,29,30-

Trisnorhopane 

STER37 20S-13a(H),17ß(H)-diasterane HOP14 17a(H),18a(H),21ß(H)-25,28,30-

Trisnorhopane 

STER38 20R-13a(H),17ß(H)-diasterane STER53 20R5a(H),14a(H),17a(H)-

stigmastane 

STER39 20S-13ß(H),17a(H)-diasterane HOP15 17a(H),21ß(H)-22,29,30-

Trisnorhopane 

STER42 C27-20S5a(H),14a(H)- HOP16 17a(H),18a(H),21ß(H)-28,30-

cholestane Bisnorhopane 

STER43 20R5a(H),14ß(H)-cholestane HOP17 17a(H),21ß(H)-30-Norhopane 

STER44 C27-20S5a(H),14ß(H),17ß(H)- HOP18 18a(H),21ß(H)-30-Norneohopane 

cholestane 

STER45_40 20R5a(H),14a(H),17a(H)- HOP19 17a(H),21ß(H)-Hopane 

cholestane&C29-

20S13ß(H),17a(H)-diasterane 

STER46 20S5a(H),14a(H),17a(H)- HOP20 17ß(H),21a(H)-hopane 

ergostane 

STER47 20R5a(H),14ß(H),17ß(H)- HOP21 22S-17a(H),21ß(H)-30-

ergostane Homohopane 

STER48 20S5a(H),14ß(H),17ß(H)- HOP22 22R-17a(H),21ß(H)-30-

ergostane Homohopane 

STER41 20R-13a(H),17ß(H)-diasterane HOP23 17ß(H),21ß(H)-Hopane 

HOP9 C27-tetracyclic terpane HOP24 22S-17a(H),21ß(H)-30,31-

Bishomohopane 

STER49 20R5a(H),14a(H),17a(H)- HOP25 22R-17a(H),21ß(H)-30,31-

ergostane Bishomohopane 

HOP10 C27-tetracyclic terpane HOP26 22S-17a(H),21ß(H)-30,31,32-

Trisomohopane 

HOP11 C28-tetracyclic terpane HOP27 22R-17a(H),21ß(H)-30,31,32-

Trishomohopane 

STER50 20S5a(H),14a(H),17a(H)- STER51 20R5a(H),14ß(H),17ß(H)-

stigmastane stigmastane 

HOP12 C28-tetracyclic terpane 

Polar Organic Compounds 

HEXAC hexanoic acid HEPDAC heptanedioic (pimelic) acid 

HEPTAC heptanoic acid ACVAN acetovanillone 

BENAC benzoic acid PHTHAC phthalic acid 

OCTANAC octanoic acid LEVG levoglucosan 

MALEAC maleic acid TDECAC tridecanoic acid 

SUCAC succinic acid ISPHAC isophthalic acid 

MEGUA4 4-me-guaiacol AZEAC azelaic acid 

MESUCAC me-succinic acid MYRAC myristic acid 

NONAC nonanoic acid PDECAC pentadecanoic acid 

ETGUA4 4-ethyl-guaiacol PALAC palmitic acid 

GUAC glutaric acid HEPTAD heptadecanoic acid 

79
Mnemonic Compound Mnemonic Compound 

SYRI syringol OLAC oleic acid 

DIMEB25 2,5-dimethylbenzoic acid ELAC elaidic acid 

DIMEB24 2,4-dimethylbenzoic acid STEAC stearic acid 

DIME235 2,3- and 3,5- dimethylbenzoic NDECAC nonadecanoic acid 

acid 

DECAC decanoic acid DHABAC dehydroabietic acid 

ALGUAI4 4-allyl-guaiacol (eugenol) ECOSAC eicosanoic acid 

MESYR4 4-methyl-syringol ABAC abietic acid 

DIMEB34 3,4-dimethylbenzoic acid HCOSAC heneicosanoic acid 

HEXDAC hexanedioic (adipic) acid DOCOSA docosanoic acid 

CPINAC cis-pinonic acid TRICOSA tricosanoic acid 

SALCYL salcylic acid TETRACO tetracosanoic acid 

FGUAI4 4-formyl-guaiacol (vanillin) CHOL cholesterol 

UNDEC undecanoic acid BSIT sitosterol 

ISEUG isoeugenol 

Alkanes and Cycloalkanes 

NOYCYHX Nonylcyclohexane EICOSA Eicosane 

HPYCYHX Heptylcyclohexane HENEIC Heneicosane 

OCYCYHX Octylcyclohexane DOCOSA Docosane 

NORFARN Norfarnesane TRICOSA Tricosane 

FARNES Farnesane DEC5YHX Pentadecylcyclohexane 

TEDRAD Tetradecane DEC6YHX Hexadecylcyclohexane 

PENTAD Pentadecane DEC7YHX Heptadecylcyclohexane 

HEXAD Hexadecane_Norpristane DEC8YHX Octadecylcyclohexane 

HEPTAD Heptadecane_Pristane DEC9YHX Nonadecylcyclohexane 

OCTAD Octadecane COSAN4 Tetracosane 

NONAD Nonadecane COSAN5 Pentacosane 

PHYTAN Phytane COSAN6 Hexacosane 

DECYHX Decylcyclohexane COSAN7 Heptacosane 

DEC1YHX Undecylcyclohexane CYHXEIC Eicosylcyclohexane 

DEC2YHX Dodecylcyclohexane CYHXHEN Heneicosylcyclohexane 

DEC3YHX Tridecylcyclohexane COSAN8 Octacosane 

DEC4YHX Tetradecylcyclohexane 

Nitro-PAH 

NI1NAPTH 1-nitronaphthalene NI2FLUOR 2-nitrofluoranthene 

NI2NAPTH 2-nitronaphthalene NI3FLUOR 3-nitrofluoranthene 

NI2BIPH 2-nitrobiphenyl NI1PYRE 1-nitropyrene 

NI3BIPH 3-nitrobiphenyl NI27FLUO 2,7-dinitrofluorene 

NI4BPH 4-nitrobiphenyl NI27FL9ON 2,7-dinitrofluoren-9-one 

NI13NAP 1,3-dinitronaphthalene NI7BZANTH 7-nitrobenz(a)anthracene 

NI15NAP 1,5-dinitronaphthalene NI6CHRY 6-nitrochrysene 

NI5ACEN 5-nitroacenaphthene NI13PYR 1,3-dinitropyrene 

NI9ANTHR 9-nitroanthracene NI16PYR 1,6-dinitropyrene 

NI4PHEN 4-nitrophenanthrene NI18PYR 1,8-dinitropyrene 

NI9PHEN 9-nitrophenanthrene NI910ANTH 9,10-dinitroanthracene 

NI3PHEN 3-nitrophenanthrene NI6BAP 6-nitrobenz[a]pyrene 

NI18NAP 1,8-dinitronaphthalene 

The data were delivered in electronic format in units of ng/m3

. No unusual events for this 

group of samples were noticed. 

80 
Fuel and Oil Samples 

Six fuel and five oil samples were analyzed for PAH and hopanes/steranes. The data 

were presented in units of ug/ml and ug/g. Figure 60 shows the PAH concentrations in 

diesel fuel and oil. For simplicity, the methylated isomeric PAH were added together 

(i.e. dimethylnaphthalenes, trimethylnaphthalenes, etc). As seen from this figure, the 

lower molecular weight (MW) PAHs were much more abundant in diesel fuel than in the 

oil. Methylated PAH account for the majority of the PAH. 

Lower MW PAH 

CRC44 CRC43 CRC42 CRC41 CRC40 CRC39 CRC44 CRC43 CRC42 CRC40 CRC39 

FUEL FUEL FUEL FUEL FUEL FUEL OIL OIL OIL OIL OIL 

naphth mnaph2 mnaph1 biphen dmnaphth mbiphen dbzfur bibenz tmnaphth 

acnapy acnape fluore phenan mflu fl9one xanone acquone pnapone 

mphenan anthone anrquone dmphenan 

Higher MW PAH 

CRC44 CRC43 CRC42 CRC41 CRC40 CRC39 CRC44 CRC43 CRC42 CRC40 CRC39 

FUEL FUEL FUEL FUEL FUEL FUEL OIL OIL OIL OIL OIL 

anthra m_9ant fluora pyrene antal9 retene bntiop mflu/mpy bzcphen baanth m_7baa chrysn 

bzanthr baa7_12 chry56m bbjkfl m_7bpy bepyrn peryle bapyrn incdpy bghipe dbanth corone 

Figure 60: PAH in fuels and oils. 

0 

5000 

10000 

15000 

20000 

25000 

30000 

ug/g 

0 

100 

200 

300 

400 

500 

600 

ug/g 

81 
Volatile Organic Compounds 

Canister Samples 

Table 14 lists the compounds quantified on-site from the canister samples by the GC/MS 

method. The MDL was 0.1 ppbv for all compounds. 

Table 14: List of Gas-phase Compounds Quantified by GC/MS Method from 

Canisters. 

Mnemonic Compound Mnemonic Compound 

ethane ethane pa224m 2,2,4-trimethylpentane 

ethene ethene n_hept n-heptane 

acetyl acetylene p2e23m 2,3-dimethyl-2-pentene 

lpropa propane t13dcp t-1,3-dichloropropene 

lprope propene mecyhx methylcyclohexane 

lpropy propyne pa234m 2,3,4-trimethylpentane 

ibuta iso-butane tolue toluene 

but1e_ibute 1-butene + isobutene hx23dm 2,3-dimethylhexane 

bud13 1,3-butadiene hep2me 2-methylheptane 

butan n-butane hep4me 4-methylheptane 

t2but t-2-butene hep3me 3-methylheptane 

c2but c-2-butene hex225 2,2,5-trimethylhexane 

bud12 1,2-butadiene n_oct n-octane 

ipent iso-pentane etbz ethylbenzene 

pente1 1-pentene mp_xyl m/p-xylene 

b1e2m 2-methyl-1-butene oct3me 3-methyloctane 

n_pent n-pentane styr styrene 

i_pren isoprene o_xyl o-xylene 

t2pene t-2-pentene n_non n-nonane 

c2pene c-2-pentene iprbz i-propylbenzene 

b2e2m 2-methyl-2-butene ipcyhex isopropylcyclohexane 

bu22dm 2,2-dimethylbutane a_pine alpha-pinene 

cpente cyclopentene n_prbz propylbenzene 

cpenta cyclopentane m_etol 3-ethyltoluene 

bu23dm 2,3-dimethylbutane p_etol 4-ethyltoluene 

pena2m 2-methylpentane bz135m 1,3,5-trimethylbenzene 

pena3m 3-methylpentane o_etol 2-ethyltoluene 

p1e2me 2-methyl-1-pentene b_pine beta-pinene 

n_hex n-hexane bz124m_tbutbz 1,2,4-trimethylbenzene+tbutylbenzene 

t2hexe t-2-hexene n_dec n-decane 

p2e2me 2-methyl-2-pentene bz123m 1,2,3-trimethylbenzene 

p2e3mt 3-methyl-2-pentene limon limonene 

c2hexe c-2-hexene indan indan 

p2e3mc cis-3-methyl-2-pentene detbz13 1,3-diethylbenzene 

hxdi13 1,3-hexadiene (trans) detbz14 1,4-diethylbenzene 

mcypna methylcyclopentane n_bubz butylbenzene 

pen24m 2,4-dimethylpentane prtol propyltoluene 

cpene1 cyclopentene iprtol isopropyltoluene 

82 
Mnemonic Compound Mnemonic Compound 

benze benzene n_unde n-undecane 

cyhexa cyclohexane bz1245 1,2,4,5-tetramethylbenzene 

hexa2m 2-methylhexane bz1235 1,2,3,5-tetramethylbenzene 

pen23m 2,3-dimethylpentane ind_2m 2-methylindan 

hexa3m 3-methylhexane ind_1m 1-methylindan 

cyhexe cyclohexene 

cpa13m 1,3-dimethylcyclopentane (cis) 

hep1e 1-heptene 

After the first dynamic system background run, a very high acetone peak that obscured 

the iso-pentane peak was noticed. This peak persisted for a few subsequent runs but 

gradually diminished. The system (i.e. dilution tunnel and all sampling lines) was 

flushed overnight with ambient air on January 13, and the peak was nearly gone. 

Unfortunately it reappeared again on January 21. In addition, some other peaks identified 

as n-pentane, n-hexane, and 2-methyl-1-pentene were unusually high for some runs. 

Clearly, this appears to be a contamination with some solvent, or mixture of solvents, but 

the origin of the contamination was not determined. 

Carbonyl Compounds 

Table 15 lists the carbonyl compounds collected on DNPH cartridges and quantified by 

the HPLC method. The MDL for carbonyl compounds was approximately 0.1 ppbv. 

Table 15: List of Target Analytes in the Gas-Phase Carbonyl Compound Fraction 

Mnemonic Compound 

FORMAL Formaldehyde 

ACETAL Acetaldehyde 

ACETO Acetone 

ACROLN Acrolein 

PROAL Propionaldehyde 

CROTON Crotonaldehyde 

MEK Methyl ethyl ketone 

MACROL Methacrolein 

BUTAL Butyraldehyde 

BENZAL Benzaldehyde 

GLYOXL Glyoxal 

VALAL Valeraldehyde 

TOLUAL M-tolualdehyde 

HEXAL Hexanaldehyde 

The acetone contamination is clearly visible in these samples as well. Figure 61 shows 

the concentrations of carbonyl compounds (in ppbv) measured during various runs 

(shown in chronological sequence). 

83 
Carbonyls 

2000 

hexal 

ppbv 

1800 tolual

5250 11901 1600 valal 

1400 glyoxl 

1200 benzal 

1000 butal 

macrol 

mek 

800 

600 

croton 400 

proal 200 

acroln 

0 aceto 1 

3 

8 

2

9

9 

2

2

7 

7

3 

1

#

63

6

63

6

72

7

7

7

79

G #2

86

9

9

0

03 

13

#

2

21

G

8

8

8

8

8

8

8

8

8

9

90

9

9

acetal E

S

E 28

E

O 2

L

K

E 28

I

N

3 

3 

L

IS

2

ANS 2

E 2

DL

 2

SE 2

L 33 28

O 2

C

DL

ANS 2

E 2

E 29

S 2

2

2

G

E 2

A

S 29

BACK

I

I

L

IS

S

E3

N

ID

I

RANS

D

D

I

A

DLE3

BACK

formal T

RU

T

RU

ID

T

RU

RU

TR

I

I

RU

TR

R

C

C

MH

MH

BA

R

C

C

DL

C

Figure 61: Concentrations of carbonyl compounds (in ppbv) measured during the 

runs. 

For the cycles with sequence numbers 2886 (combining two idle33) and 2892 (six runs 

including a pair of Transient modes, Cruise modes, and HHDDT_S modes respectively), 

back-up cartridges were used to check for breakthrough. In general, the breakthrough 

was negligible. 

Nitrosoamines 

Table 16 shows the nitrosoamines measured for this program. 

Table 16: Nitrosoamines Targeted for Analysis in the Vehicle Exhaust 

Compound Name LQL a (μg/sample) 

Nitrosoamines 

n-nitrosomorpholine 0.01 

n-nitrosodiethylamine 0.01 

n-nitrosodimethylamine 0.01 

n-nitrosodibutylamine 0.01 

n-nitrosopyrolidine 0.01 

The concentrations of nitrosoamines in the exhaust were low, close to the MDL. It 

should be noted that due to the sampling on the same Thermosorb cartridge over all 

cycles from the individual vehicle, any invalidated run was also sampled on the same 

cartridge. Three samples out of the six collected have invalidated runs sampled on the 

cartridge: samples collected on 01/09/04, 01/16/04, and 1/28-1/30/04. 

84 
Tenax Samples 

Table 17 lists compounds quantified from Tenax cartridges. The MDL for these 

compounds was in the range of 0.1 ppbv per sample. 

Table 17: List of Heavy Hydrocarbons for Tenax Samples 

Mnemonic Compound Mnemonic Compound 

HEPAL Heptanal IPRXYL_5 5-isopropyl-m-xylene 

N_NON Nonane BZ1245 1,2,4,5-tetramethylbenzene 

IPRBZ Isopropylbenzene BZ1235 1,2,3,5-tetramethylbenzene 

N_PRBZ Propylbenzene IAMBZ Isoamylbenzene 

M_ETOL m-ethyltoluene IND_2M 2-methylindan 

P_ETOL p-ethyltoluene IND_1M 1-methylindan 

BZ135M 1,3,5-trimethylbenzene BZ1234 1,2,3,4-tetramethylbenzene 

PHENOL Phenol DIPRB_13 1,3-diisopropylbenzene 

O_ETOL o-ethyltoluene C5BZ_3 Pentylbenzene 

FURBZ 2,3-benzofuran THNAPH 1,2,3,4-tetrahydronaphthalene 

FURPEN 2-pentylfuran DHNAPH 1,2-dihydronaphthalene 

T_BUBZ t-butylbenzene DIPRB_14 1,4-diisopropylbenzene 

OCTAL Octanal NAPHTH Naphthalene 

BZ124M 1,2,4-trimethylbenzene INDDMA A-dimethylindane 

MESTYR 4-methylstyrene INDDMB B-dimethylindane 

MPCBZ 1,3-dichlorobenzene INDDMC C-dimethylindane 

DEC1E 1-decene INDDMD D-dimethylindan 

I_BUBZ Isobutylbenzene DECONE2 2-decanone 

N_DEC Decane DECAL Decanal 

S_BUBZ Sec-butylbenzene DODE1E Dodecene 

BZ123M 1,2,3-trimethylbenzene N_DODE Dodecane 

M_IPRTOL m-isopropyltoluene PMEBZ Pentamethylbenzene 

P_IPRTOL p-isopropyltoluene NAP_2M 2-methylnaphthalene 

ODCBZ 1,2-dichlorobenzene NAP_1M 1-methylnaphthalene 

INDAN Indan N_TRID Tridecane 

INDENE Indene BIPHEN Biphenyl 

O_IPRTOL o-isopropyltoluene ENAP12 1+2-ethylnaphthalene 

O_MEPHOL o-methylphenol DMN267 2,6+2,7-dimethylnaphthalene 

DETBZ1 1,3-diethylbenzene N_TETD Tetradecane 

M_TOLALD m-tolualdehyde DM1367 1,6+1,3+1,7-dimethylnaphthalene 

TOL4PR 4-n-propyltoluene + 1,4-diethylbenzene D14523 2,3+1,5+1,4-dimethylnaphthalene 

BUTBZ Butylbenzene ACENAP Acenaphthylene 

M_XYLET5 5-ethyl-m-xylene DMN12 1,2-dimethylnaphthalene 

DETBZ3 1,2-diethylbenzene ACENPE Acenaphthene 

MP_MEPHO m/p-methylphenol N_PEND Pentadecane 

TOL2PR 2-n-propyltoluene FLUORE Fluorene 

P_XYLET2 2-ethyl-p-xylene N_HEXD Hexadecane 

O_XYLET4 4-ethyl-o-xylene N_HEPD Heptadecane 

TBUTOL_4 4-tert-butyltoluene PHENA Phenanthrene 

NONAL Nonanal N_OCTD Octadecane 

UNDE1E 1-undecene N_NOND Nonadecane 

85
Mnemonic Compound Mnemonic Compound 

FUBZ2ME 2-methylbenzofuran N_EICO Eicosane 

N_UNDE Undecane 

Since Tenax samples cannot be combined for analyses, each replicate run was analyzed 

separately. Nine samples were invalidated due to problems with the B sampling channel 

and damage to some of the A cartridges during transport. These samples are shown in 

Table 18. 

Table 18: Damaged Tenax Samples. 

Cycle Test ID 

Test Run 

ID 

Cruise3 2863 09 

Cruise3 3863 10 

MHDTLO 2879 06 

MHDTLO 2879 07 

MHDTCR 2879 08 

MHDTCR 2879 09 

Idle33 2907 03 

Idle33 2913 01 

Idle33 2913 02 

Trans3 2921 01 

Cruise3 2921 05 

Cruise3 2921 06 

86 
SPECIATION AND SIZING RESULTS 

This section discusses exhaust particle size distributions (SMPS and DMS500) and 

chemical speciation results for five heavy heavy-duty diesel trucks operating on various 

modes of the California HHDDT cycle. Particle size distribution results from the SMPS 

were corrected for dilution ratios. Since dilution ratio on the main tunnel was not 

accurately known, DMS500 data presented in this report are for dilute flow in the main 

CVS tunnel. The raw uncorrected results obtained from DRI’s analytical laboratory for 

chemical speciation were presented in ng/m3

. All speciation data were reduced by 

correcting for flow rates in the sampling system. The mass values for chemical speciation 

were found using the equation 

g/cycle of chemical species= (Vtunnel* Speciated sample in ng/ m3

)/ 1.00E+09. 

Vtunnel = Vmix + Total PM volume + PM10 volume + DRI volume (m3

). 

Vmix was the total integrated volume sampled from the venturi for a particular cycle. 

Total PM volume was the integrated volume sampled from the secondary dilution tunnel 

for a particular cycle. PM10 volume was the integrated volume sampled from the PM10 

cyclone for a particular cycle. DRI operated three PM2.5 cyclones at 113 lpm each; e.g., 

0.34 m3

/min total. To obtain the total DRI sample volume, 0.34 m3/min was multiplied by 

the sample time. The PM10 and DRI flows were small with respect to tunnel flow. 

Chemical speciation results are usually reported in g/mile, but since Idle mode was also 

considered for comparison purposes, all speciation data are presented in g/hour. Only for 

chemical speciation, both the Cruise Modes were integrated and results reflect the 

combination of both the normal and High-speed Cruise Modes. 

The data are depicted as “Tunnel Background” and “Test, Uncorrected” to illustrate the 

magnitude of reductions, while being mindful of the role the tunnel background plays 

when the primary emissions are so low. 

Results presented for chemical speciation were not corrected for background values, 

which is a departure from regulatory compliance reporting, and is different from the 

treatment of regulatory emissions presented in this report. Background data are provided 

separately. There are two barriers to representing data with background correction. First, 

the exhaust dilution ratio in the main CVS was not known. The background correction for 

regulated species was performed using a dilution factor, prescribed in the Code of Federal 

Regulations (CFR), and this factor is not equal to the ratio. Second, background levels of 

each species are known to vary with time, so that accurate quantitative correction is not 

possible without parallel sampling trains. Finally, the role played by the tunnel 

background, and tunnel history effects in speciation results is an unknown. 

87 
E55CRC-39 

E55CRC-39 was powered with a Cummins ISX 530 MY 2004 engine. Particle sizing and 

chemical speciation results are presented below for various modes of the HHDDT 

schedule. Figure 62 and Figure 63 present the SMPS particle size distribution for Idle and 

steady modes. 

A very distinct clear bimodal distribution was noted for the Idle mode with a nuclei mode 

in the particle size range of 18 nm and an accumulation mode of 157 nm with 

concentrations in the range of 3.5x105 and 1.5x105, respectively. The nuclei mode 

formation is attributed to low engine load at Idle conditions. Exhaust temperatures are 

low under idling conditions, which lead to formation of higher levels of volatile organic 

compounds. 

These volatile compounds are usually in the gas phase in the tailpipe. As the exhaust is 

diluted and cooled in the atmosphere or the dilution system, these volatile compounds 

may either adsorb the nucleated sulfuric acid and/or undergo homogenous nucleation to 

form particles. Some semi-volatile particles adsorb onto existing soot particles and 

increase their size and these particles are measured as the agglomeration mode particles. 

Nuclei mode particles do not contribute much towards Idle mass emissions as seen in 

Figure 64, but their number concentrations are high. 

4.00E+05 

3.50E+05 

3.00E+05 

2.50E+05 

2.00E+05 

1.50E+05 

1.00E+05 

5.00E+04 

1.00E+01 

10 100 1000 

Particle Diameter (nm) 

Particle Number Concentration (dN/dlogDp) #/cm^3 

Figure 62: SMPS Particle Size Distribution for E55CRC-39 Operating on an Idle 

Mode 

88 
Particle Number Concentration (dN/dlogDp) #/cm^ 4.00E+06 

3.50E+06 

3.00E+06 

2.50E+06 

2.00E+06 

1.50E+06 

1.00E+06 

5.00E+05 

1.00E+01 

Steady State 

Cruise3 

HHDDT_S 

g/hour 

1 10 100 1000 Particle Diameter (nm) 

Figure 63: SMPS Particle Size Distribution for E55CRC-39 Operating on Various 

Steady Cycles 

14 

12 

10 

8 

6 

4 

2 

0

Idle Cruise3 HHDDT_S

Figure 64: PM Mass Emissions for E55CRC-39 

Chemical speciation of exhaust from E55CRC-39 showed that volatile organic compound 

emissions were very high in the Idle mode at 0.68 g/hour when compared to the Cruise 

mode at 0.21g/hour (Appendix O: Figure O1 to O5). In the semi-volatile group, polar 

compound emissions for the Cruise mode were very similar to Idle mode emissions 

89 
(Appendix O: Figure O9). The elemental carbon emissions for the Cruise mode were very 

high at 8.3 g/hour when compared with the Idle mode at 0.21 g/hour (Figure 66). At idle, 

the volatile compounds experience lower temperatures after being emitted or in the tail 

pipe. The saturation ratios (partial pressure/saturation pressure) are also higher in light of 

the fact that elemental carbon is present in very low quantities; hence, idle operation PM 

emissions are driven by the lower exhaust temperatures and higher saturation ratios. The 

lower concentration of elemental carbon contributes to nucleation of nano-particle 

formation. These analyses clearly indicate that, for this vehicle, the nano-particles or 

nuclei mode particles which are measured during the Idle Mode, are mostly made up of 

volatile compounds. The heavier organic species undergo condensation onto the hetromolecular complex of water, sulfuric acid and lubricating oil based nano-sized ash 

particles. For the steady state mode at 40 kmph (25mph), the Count Median Diameter 

(CMD) of the particle size distribution was 48.89 nm with a maximum concentration 

level of 1x106

 particles/cm3. For the High-speed Cruise and normal Cruise Mode, the 

particle size distribution was very similar with a CMD of 75.91 and 71.84 nm, 

respectively. The concentration levels for the Cruise Modes were almost twice that of the 

steady state mode and almost ten times that of the Idle Mode. 

The geometric standard deviation (GSD) for the steady state, Cruise and High-speed 

Cruise Modes were 1.83, 1.84 and 1.79, respectively. The geometric standard deviation 

represents the distance of shift from the mean of the whole distribution. GSD values close 

to 1.8 represent a good distribution about the mean for diesel exhaust. For the Idle mode 

the GSD was 2.9 which indicates that the distribution was skewed and this can also be 

inferred from Figure 62. The shift towards a higher particle size in the Cruise Modes was 

likely due to a higher concentration of carbonaceous agglomerates in the exhaust, which 

also tend to suppress nano-particle formation (see Figure 63). Sulfate emissions were 

almost 20 times higher in the Cruise mode than in the Idle mode (Figure 66). Acetone 

emissions were unusually high for the Transient mode at 212.4 g/hour (Appendix O: 

Figure O11). 

On a mass basis, the contribution of nitro-PAH and hopanes & steranes compounds 

(Appendix O: Figure O8 and O10) were not significant. Sulfates along with semi-volatile 

and carbonyl compounds usually adsorb onto carbon particles and form a cluster-like 

structure which increases the size of the particles, and the size spectrum is shifted 

towards the larger accumulation mode which is evident from Figure 63. These analyses 

show that accumulation mode particles formed during the Cruise mode are mostly made 

up of semi-volatile compounds with a solid carbonaceous core. 

90 
Idle Trans Cruise 

g/hour 0.00 

0.20 

0.40 

0.60 

0.80 

1.00 

1.20 

Soluble Calcium 

Soluble Potassium 

Soluble Magnesium 

Soluble Sodium 

Ammonium 

Sulfate 

Nitrate 

Nitrite 

Chloride 

Figure 65: Ion Composite Results for E55CRC- 39 

Idle Trans Cruise 

0 

2 

4 

6 

8 

10 

12 

g/hour 

Elemental Carbon 

Organic Carbon 

Figure 66: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-39 

91 
0.00E+00 

5.00E+05 

1.00E+06 

1.50E+06 

2.00E+06 

2.50E+06 

Total Number of Particles 

(N/cc) 

-100 

-80 

-60 

-40 

-20 

0 

20 

40 

60 

Vehicle Speed (mph) 

0 200 400 600 800 1000 

Time (s) 

Total Number (N/cc) Vehicle Speed (mph) 

Figure 67: DMS500 Total Number of Particles and Vehicle Speed vs. Time during 

the UDDS for E55CRC-39 tested at 56,000 lbs. 

Comprehensive DMS500 data are available for E55CRC-39. Figure 67 shows the total 

number of particles and vehicle speed versus time during the UDDS for E55CRC-39. The 

total number goes as high as 1.5x106 particles/cm3 during steep accelerations and goes 

down to 1.5x104

 during idle conditions. There is no strong correlation between the total 

number and engine speed, but as can be observed from Figure 67, during accelerations, 

the total number was high and when the high speed was continued for a period, the total 

number started to drop, e.g., between t = 600 and 700s. During decelerations, the total 

number dropped to a minimum and continued that way during the idle period. 

Figure 68 shows the total number of particles and engine power versus time. Figure 69 

shows the distribution of the total number concentration of particles in the 60 and 20 nm 

bins versus time. The 60 nm bin contains particles of diameters between approximately 

55 and 65 nm, and the diameters for the 20 nm bin range between 17.5 and 22.5 nm. As 

can be observed from the plot, the overall number of 60 nm particles, which represent the 

accumulation mode particles, are almost an order of magnitude higher than the total 

number of particles in the 20 nm bin. Figure 70 shows the total number of particles in the 

60 nm bin versus the total number of particles in the 20 nm bin. There is a much sharper 

increase in the total number of particles in the 20 nm bin during decelerations and a 

sharper increase in the total number of particles in the 60 nm bin during accelerations. As 

can be seen, there is no clear correlation between the two size bins. 

92 
Total Particle Number (N/cc) 

2.50E+06 

500 

2.00E+06 0 

1.50E+06 -500 

1.00E+06 -1000 

5.00E+05 -1500 

0.00E+00 -2000 

Engine Power (hp) 

0 200 400 600 800 1000 

Time (s) 

Total Number of Particles (N/cc) Engine Power (hp) 

Figure 68: DMS500 Total Number of Particles and Engine Power vs. Time during 

the UDDS for E55CRC-39 tested at 56,000 lbs. 

2.00E+05 

2.00E+04 

1.80E+05 

1.50E+04

1.60E+05 

1.00E+04 

60 nm bin (N/cc) 1.40E+05 20 nm bin (N/cc) 

5.00E+03 1.20E+05 

0.00E+00 1.00E+05 

-5.00E+03 8.00E+04 

-1.00E+04 6.00E+04 

4.00E+04 -1.50E+04 

2.00E+04 -2.00E+04

0.00E+00 -2.50E+04 

0 200 400 600 800 1000 

Time (s) 

60 nm 20 nm 

Figure 69: DMS500 60 nm and 20 nm Particle Number vs. Time during the UDDS 

for E55CRC-39 tested at 56,000 lbs. 

93 
1.40E+05 

1.20E+05 

1.00E+05 

60 nm bin N/cc) 8.00E+04 

6.00E+04 

4.00E+04 

y = 1.2398x + 12597 

R2

 = 0.0365 2.00E+04 

0.00E+00 

0.00E+00 5.00E+03 1.00E+04 1.50E+04 2.00E+04 2.50E+04 

20 nm bin (N/cc) 

Figure 70: DMS500 60 nm Particle Number vs. 20 nm Particle Number during the 

UDDS for E55CRC-39 tested at 56,000 lbs. 

1.E+05 

1.E+05 

60nm Bin Number (N/cc)

1.E+05 

8.E+04 

6.E+04 

4.E+04 

y = 74.011x + 13301 

R2

 = 0.305 2.E+04 

0.E+00 

-800 -600 -400 -200 0 200 400 600 

-2.E+04 

-4.E+04 

Total Hub Power (hp) 

Figure 71: DMS500 60 nm Particle Number vs. Total Hub Power during the UDDS 

for E55CRC-39 tested at 56,000 lbs. 

94
Chart Title 

3.E+04

60nm Bin Number (N/cc) 

2.E+04 

2.E+04 

1.E+04 

y = -1.3706x + 1975.8 

R2

 = 0.0044 

5.E+03 

0.E+00 

-800 -600 -400 -200 0 200 400 600 

Total Hub Power (hp) 

Figure 72: DMS500 20 nm Particle Number vs. Total Hub Power during the UDDS 

for E55CRC-39 tested at 56,000 lbs. 

Figure 71 shows the total number concentration of particles in the 60 nm bin versus the 

total hub power. There is no strong correlation, but the total number shows an upward 

trend with the positive hub power range. Since 60 nm particles are in the accumulation 

mode, one would expect their count to rise when higher power operation demands lower 

air to fuel ratio. Figure 72 shows the total number concentration of particles in the 20 nm 

bin versus the total hub power. Again, there is no strong correlation between the two 

series but in this case as one can observe from the plot, there are more particles in the 

negative hub power periods, that is during decelerations. This is something to be 

expected since nuclei mode particles are dominant during the deceleration phases. 

The following plots show the size distribution of particles during idle, acceleration and 

deceleration, respectively for E55CRC-39. As can be observed from Figure 73, particles 

of around 150 nm are mostly observed. This peak size agrees well with the 157 nm peak 

for the SMPS data, shown in Figure 62, but the nuclei mode peak evident in the SMPS 

plot is absent. One must note that the dilution system used for the two devices differed. 

During acceleration, as shown in Figure 74, a bimodal distribution is observed where 

there are two peaks centered at around 58 and 135 nm, respectively. This plot shows the 

transition from the Idle Mode, where particles of diameter 150 nm are dominant, to the 

acceleration mode, where particles of diameter around 60 nm are observed, which are the 

accumulation mode particles. Strong modes in the 50 to 100 nm range were observed for 

the SMPS data shown in Figure 63. Figure 75 shows the distribution during the 

deceleration region of the UDDS. Again, a bimodal distribution is seen. This time, the 

95 
transition is from deceleration to Idle Mode. The first peak is centered around 15 nm, 

which are mostly nuclei mode particles, and the second peak is centered around 175 nm, 

which is the Idle region distribution. 

Idle (t = 230 s) 

4500

4000

3500

3000

2500

2000

1500

1000

500

0

0 100 200 300 400 500 600 700 800 900 1000

Diameter (nm) 

Figure 73: DMS500 size distribution of particles during Idle (t = 230 s) of the UDDS 

for E55CRC-39 tested at 56,000 lbs. 

Number of Particles (N/cc) 

96 
Acceleration (t = 530 s) 

Number of Particles (N/cc) 

18000 

16000 

14000 

12000 

10000 

8000 

6000 

4000 

2000 

0 

0 100 200 300 400 500 600 700 800 900 1000 

Diameter (nm) 

Figure 74: DMS500 size distribution of particles during acceleration (t = 530 s) of 

the UDDS for E55CRC-39 tested at 56,000 lbs. 

Deceleration (t = 770 s) 

4500 

Number of Particles (N/cc) 4000 

3500 

3000 

2500 

2000 

1500 

1000 

500 

0 

0 100 200 300 400 500 600 700 800 900 1000 

Diameter (nm) 

Figure 75: DMS500 size distribution of particles during deceleration (t = 770 s) of 

the UDDS for E55CRC-39 tested at 56,000 lbs. 

97 
9.E+06

1.E+07 

2.E+06 

3.E+06 

4.E+06 

5.E+06 

6.E+06 

7.E+06 

8.E+06 

0 100 200 300 400 500 600 700 

Time (s) 

Total Number of Particles (N/cc) 

HHDDT_S (1) 

HHDDT_S (2) 

Vehicle Speed 

70 

60

50

Vehicle Speed (mph) 

40

30

20

10

1.E+06

0.E+00 0 

Figure 76: DMS500 size distribution of particles during HHDDT_S and Vehicle 

Speed vs. Time for E55CRC-39 tested at 56,000 lbs. 

Total Number of Particles (N/cc) 

2.E+06 

2.E+06 

2.E+06 

1.E+06 

1.E+06 

1.E+06 

8.E+05 

6.E+05 

4.E+05 

2.E+05 

0.E+00 

TRANS3 (1) 

TRANS3 (2) 

Vehicle Speed (mph) 

20 

0 

-20 

-40 

-60 

-80 

0 100 200 300 400 500 600 

Time (s) 

40 

Vehicle Speed (mph) 

Figure 77: DMS500 size distribution of particles during Transient and Vehicle 

Speed vs. Time for E55CRC-39 tested at 56,000 lbs. 

98 
Figure 76 shows the total number of particles, determined using the DMS500 and vehicle 

speed versus time during HHDDT_S for E55CRC-39. As can be observed, the total 

number of particles is as high as 9x106

 during steep accelerations, and drops to 9x104 

particles/cm3

 during idle regions. Looking at the data profiles for the two tests, the 

problem may be that the DMS500 inlet probe was not properly mounted on the second 

HHDDT_S test, thus sucking in air from the ambient and causing a decrease in the 

particle number concentration readings." 

Figure 77 shows the total number of particles, measured by the DMS500, and vehicle 

speed versus time for two different Transient runs. Again, as it is observed from previous 

plots, the total number of particles increases during accelerations and decreases during 

decelerations. During the High-speed Cruise section, the total number starts to decrease 

due to the decrease in the total number of accumulation mode particles. Repeatability is 

good for the two traces in Figure 77. 

2.E+06 

2.E+06 

Total Particle Number (N/cc) 

-80 

-60 

-40 

-20 

0 

20 

40 

60 

Vehicle Speed (mph) 

CRUISE3 (1) 

CRUISE3 (2) 

Vehicle Speed 

Data Transfer Error 

3.E+06

1.E+06 

5.E+05 

0.E+00 

0 500 1000 1500 2000 

Time (s) 

Figure 78: DMS500 size distribution of particles during Cruise3 and Vehicle Speed 

vs. Time for E55CRC-39 tested at 56,000 lbs. 

Figure 78 shows the total number of particles and vehicle speed versus time for two 

different Cruise runs. During acceleration, the total number of particles increases and 

during decelerations, the total number decreases. Repeatability is not as good as 

illustrated in Figure 77, and the researchers speculate that this may have been due to the 

accumulation of PM in the instrument. This was the first operation of the instrument in 

the field by the researchers, and protocols for cleaning the instrument were not well 

established at time of testing. 

99 
E55CRC-40 

E55CRC-40 was a powered by a Detroit Diesel Series 60, MY 2003 engine. Particle 

sizing and chemical speciation results are presented below for various modes of the 

HHDDT schedule. Figure 79 and Figure 80 present the SMPS particle size distributions 

for Idle and steady modes. 

A nuclei mode dominated distribution was seen for the Idle mode with a count median 

diameter (CMD) of 25.88 nm with a concentration of 8x104

 particles/cc and a geometric 

standard deviation of 1.64. These concentration levels were almost four times lower than 

those observed for E55CRC-39. This drop in concentration could be attributed to 

difference in the emissions of volatile organic compounds. The total VOC’s emitted for 

E55CRC-40 at 2.01 g/hour during the Idle mode was almost eight times lower in 

magnitude as compared to E55CRC-39 at 15.51 g/hour. The VOC mass emission rates 

reported here include contributions from unburnt fuel and oil. It should be noted that a 

recent study by Sakurai et al.13 indicated that the volatile component of diesel particles 

was comprised primarily of unburnt lubricating oil, and that contributions from unburnt 

fuel, oxidized organic combustion products, and sulfuric acid were small. Sakurai et al.13 

also reported that the organic component of diesel nanoparticles was comprised of 

compounds with carbon numbers in the C24 – C32 range, which are almost entirely 

derived from unburnt oil. 

9.00E+04 

8.00E+04 

7.00E+04 

6.00E+04 

5.00E+04 

4.00E+04 

3.00E+04 

2.00E+04 

1.00E+04 

1.00E+01 

10 100 1000 

Particle Diameter (nm) 

Particle Number Concentration (dN/dlogDp) #/cm^3 

Figure 79: SMPS Particle Size Distribution for E55CRC-40 Operating on an Idle 

Mode 

100 
1.00E+01 

1.00E+05 

2.00E+05 

3.00E+05 

4.00E+05 

5.00E+05 

6.00E+05 

7.00E+05 

8.00E+05 

Particle Number Concentration (dN/dlogDp) #/cm^3

Steady State 

Cruise3 

HHDDT_S 

10 100 1000 

Particle Diameter (nm) 

Figure 80: SMPS Particle Size Distribution for E55CRC-40 Operating on Various 

Steady Cycles 

VOC results were very similar for E55CRC-40 when Idle and Cruise mode were 

compared (Appendix O: Figure O13 to O17). Emissions of n-hexane and 2-methyl-1-

pentene were high during the Transient mode when compared with the Idle and Cruise 

Modes (Appendix O: Figure O15 and O16). For the steady state mode, the CMD for the 

particle size distribution was 84.96 nm with a concentration of 4.5x105 particles/cm3 and 

a GSD of 1.75. Particle size distributions were markedly different for the two Cruise 

Modes with a CMD of 45.1 nm for the normal Cruise mode and 62.24 nm for the Highspeed Cruise Mode. SMPS size distributions observed in the Cruise Modes were 

characterized by the accumulation mode particles. 

The shift of the size spectrum towards a higher accumulation range during the Cruise 

Modes when compared to the Idle mode could be attributed to higher concentrations of 

carbonaceous agglomerates (EC emissions) and higher sulfate emissions during the 

Cruise Mode. Sulfate emissions were very high during the Cruise Mode at 0.27 g/hour 

when compared with the Idle mode at 0.015g/hour (Figure 83). Sulfate emissions serve as 

the precursors of particle formation seen in the nuclei mode. Sulfates would undergo a 

hetero-molecular nucleation with water molecules to form complex clusters. Subsequent 

adsorption of volatile organics and agglomeration with the elemental carbon results in the 

distribution seen in Figure 80. Elemental carbon emissions for the Cruise Mode were 

high at 5.5 g/hour when compared to the Idle mode at 0.07 g/hour (Figure 83), which also 

contributed to most of the mass emissions (Figure 82). Semi volatile emissions were 

similar for Idle and Cruise Modes except for alkanes and hopanes & steranes which were 

higher during the Cruise Mode (Appendix O: Figure O18 to O22). 

101 
Idle Cruise3 HHDDT_S 

Figure 81: PM Mass Emissions for E55CRC-40 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

g/hour 

0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

0.35 

0.40 

0.45 

0.50 

Idle Trans Cruise 

CRC 40 

g/hour 

Soluble Calcium 

Soluble Potassium 

Soluble Magnesium 

Soluble Sodium 

Ammonium 

Sulfate 

Nitrate 

Nitrite 

Chloride 

Figure 82: Ion Composite Results for E55CRC-40 

102 
0 

1 

2 

3 

4 

5 

6 

7 

8 

Idle Trans Cruise 

CRC 40 

g/hour 

Elemental Carbon 

Organic Carbon 

Figure 83: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-40 

For E55CRC-40, DMS500 data proved unreliable, and were characterized by spikes in 

the output data that did not represent credible particle counts. 

E55CRC-41 

E55CRC-41 was the only MHDT subjected to speciation. 

CRC41 was a Medium Heavy-duty Vehicle (MHDT) powered by a MY 1997 Cummins 

B5.9, 210 hp engine. The vehicle was tested over a lower speed transient, a higher speed 

Transient, and the Cruise Mode. Additionally, PM concentration and size distribution 

data was collected over the MHDT schedule that comprised of driving modes mentioned 

above. Figure 84 shows the PM size distribution over the idle mode. 

103 
Particle Concentration at Idle (using LDMA) 

Number Concentration(dN/dlogdP) 

1.00E+06 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

1.00E+00 

Idle 1 with LDMA 

1 10 100 1000 

Particle Dia(nm) 

Figure 84: SMPS Particle Size Distribution for E55CRC-41 Operating on an Idle 

Mode 

The size distribution during idle operation (Figure 84) showed a nuclei mode centered at 

40 nm and an accumulation mode of 136 nm with concentrations in the range of 1.4x105 

and 1.3x105, particles/cc, respectively. Again, the lower exhaust temperatures under 

idling conditions, and the relatively low carbonaceous soot (resulting in higher saturation 

ratios) leads to formation of higher levels of nuclei mode particles, primarily from the 

organics compounds originating from the lubricating oil. Recent studies by Gautam et 

al.14 on natural gas-fueled heavy-duty vehicles have shown evidence that supports the 

argument that lubricating oil significantly contributes to nuclei mode particles. When 

total surface area provided by soot particles is reduced the nucleation process is 

advanced. Hence, in driving modes where the elemental carbon component of the total 

PM emissions is lower, the nuclei mode particles are emitted in higher concentrations, 

provided the exhaust temperatures and relative humidity are conducive to nucleation15,16. 

The binary nucleation theory of water and sulfuric acid has been shown to underestimate 

the formation of nucleation mode particles by several orders of magnitude17. However, 

organic compounds have been considered as a key species to control the growth of 

nucleation mode particles18. 

Chemical speciation of exhaust from CRC41 showed that most volatile organic 

compounds, except for C2 to C5 alkanes, were higher in the Transient and Cruise Modes 

than in the idle mode of operation (Appendix O: Figure O25 to Figure O36). The polar 

compound emissions for the transients were the highest (Appendix O: Figure O33). The 

elemental carbon emissions for the Cruise Mode were nearly seven times higher than the 

Idle emissions (Figure 85). Figure 86 shows that total PM mass emission rates in the 

104 
cruise mode are dominated by the elemental carbon emissions. However, the organic 

carbon emissions are also significantly higher under cruise mode than under idle and 

transient modes. This breakdown is reflected in the PM concentrations and size 

distributions, as seen in Figure 84, Figure 87 and Figure 88). Cruise operation at a vehicle 

inertia of 75% GVWR shows a nuclei mode peak at 26.9 nm with a concentration of 3.9 

x 105 particles/cc when measured with a nano-DMA. The accumulation mode, with a 

CMD of 76.4 nm is similar for the cruise and steady state (25 mph) operation. Particle 

concentrations at 50% GVWR at cruising conditions did not produce any significant 

concentrations of nano-particles. This may be attributed to lower emissions of volatile 

species. Compared to the Idle and Transient Modes, emissions of sulfate emissions were 

significantly higher in the Cruise Mode (Figure 89). As noted earlier, binary nucleation of 

sulfuric acid and water do contribute to formation of nucleation mode particles, which 

may or may not survive in the exhaust depending upon levels of carbonaceous soot 

present in the exhaust stream. 

10.00 

Elemental Carbon 9.00 Organic Carbon

8.00 

7.00 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

MD Idle1 MD Idle2 MD Trans1 MD Trans2 MD Cruise1 MD Cruise2 

Runs 

g/hour 

Figure 85: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-41 

105 
25 

PM g/hour 

g/hour 

20 

15 

10 

5 

0 

MD Idle1 MD Trans1 MD Cruise1 

Figure 86: Total PM Mass Emissions Rate (g/hour) for E55CRC-41 

Particle Concentration at 75% GVWR 

Number Concentration(dN/dlogdP) 1.00E+06 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

1.00E+00 

Cruise-NDMA 

Cruise-LDMA 

Steady State at 25mph 

1 10 100 1000 

Particle Dia(nm) 

Figure 87: SMPS Particle Size Distribution for E55CRC-41 Operating under Cruise 

and Steady Conditions 

106 
Paricle Concentration at 50% GVWR 

1.00E+06 

Cruise-LDMA 

Steady State at 25mph 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

1.00E+00 

Number Concentration(dN/dlogdP) 

1 10 100 1000 

Particle Dia(nm) 

Figure 88: SMPS Particle Size Distribution for E55CRC-41 Operating on Cruise 

and Steady Conditions (50% GVWR) 

2.50 

Soluble Calcium 

2.00 

1.50 

MD Idle MD Trans MD Cruise 

Runs 

g/hour 

Soluble Potassium 

Soluble Magnesium 

Soluble Sodium 

Ammonium 

Sulfate 

Nitrate 

Nitrite 

Chloride 

1.00 

0.50 

0.00 

Figure 89: Ion Composite Results for E55CRC-41 

107 
Figure 90 to Figure 92 show traces of single particle tracking (82 nm and 24 nm) under 

transient operations. At 75% GVWR, the 82 nm particles are emitted at higher 

concentrations than the 24 nm particles. The concentration of 82 nm particles decreases 

by an order or magnitude at lower inertia weight (50% GVWR). 

CRC 41 MHDT at 75% GVWR 

Normalized Concentration(dN/dlogdP)

Tracking 82nm Particle 1.00E+10 

1.00E+09 

1.00E+08 

1.00E+07 

1.00E+06 

Test D 

1.00E+05 Low Transient 

High Transient 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

1.00E+00 

0 50 100 150 200 250 300 350 400 450 

Time (secs) 

Figure 90: SMPS Single Particle Trace (82 nm) for E55CRC-41 Operating on 

UDDS, Low Transient and High Transient Cycles (75%GVWR) 

108 

500 
CRC 41 Transient Cycle at 75% GVWR

Tracking 24nm particle

Normalized Concentration(dN/dlogdP) 1.00E+08 

1.00E+07 

1.00E+06 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

1.00E+00 

Low Transient

High Transient

0 50 100 150 200 250 300 350 

Time(secs) 

Figure 91: SMPS Single Particle Trace (24 nm) for E55CRC-41 Operating on Low 

Transient and High Transient Cycles (75% GVWR) 

CRC 41 Transient Cycle at 50% GVWR 

Tracking 88.2nm particle 

1.00E+08 

1.00E+07 

Normalized Concentration(dN/dlogdP)1.00E+06 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

1.00E+00 

AC5080 

Test D 

Low Transient 

High Transient 

0 50 100 150 200 250 300 350 400 

Time(secs) 

Figure 92: SMPS Single Particle Trace (88 nm) for E55CRC-41 Operating on Low 

Transient and High Transient Cycles (50% GVWR) 

109 
Figure 93 shows the DMS500 total number concentration of particles and vehicle speed 

versus time during the UDDS for E55CRC-41. The total number is as high as 1.7x106 

during steep accelerations and drops to 1.5x104 during Idle conditions. (There was an 

error on the readings of the instrument until t = 370s in Figure 93) In Figure 93 the high 

count between 620 and 750 seconds is due to a high count of 20 nm particles over that 

time. The overall count versus time differs in behavior between this vehicle and heavyduty vehicles, such as E55CRC-39 (see Figure 67 for UDDS data) and E55CRC-42 and 

E55CRC-43 (Figure 105 and Figure 111 for transient behavior). E55CRC-41 did not 

show a high count associated with acceleration, while the HHDDT showed this behavior 

clearly. E55CRC-41 had a smaller displacement than the HHDDT, higher engine speed, 

lower boost, two valves per cylinder (versus four for the HHDDT) and an in-line 

injection system. However, it should be speculative to associate any of these factors 

directly with the differing behavior. 

5.E+05 

1.E+06 

2.E+06 

2.E+06 

Total Particle Number (N/cc) 

-100 

-50 

0 

50 

100 

Vehicle Speed (mph) 

UDDS 

Vehicle Speed 

Data Transfer Error 

3.E+06 

0.E+00 

0 200 400 600 800 1000 

Time (s) 

Figure 93: DMS500 Total Number of Particles and Vehicle Speed vs. Time during 

UDDS for E55CRC-41 tested at 56,000 lbs. 

Figure 94 shows the distribution of the total number of particles in the 60 and 20 nm bins 

versus time. The 60 nm bin contains particles of diameters between approximately 55 and 

65 nm, and the diameters for the 20 nm bin range between 17.5 and 22.5 nm. There is a 

sharp increase in the total number of particles in the 20 nm bin during decelerations and a 

sharp increase in the total number of particles in the 60 nm bin during accelerations, 

sharp meaning a greater percentage of decrease/increase. 

110 
0.E+00 

5.E+04 

1.E+05 

2.E+05 

2.E+05 

3.E+05 

3.E+05 

4.E+05 

4.E+05 

60nm (N/cc) 

-1.E+05 

-8.E+04 

-6.E+04 

-4.E+04 

-2.E+04 

0.E+00 

2.E+04 

4.E+04 

6.E+04 

8.E+04 

1.E+05 

20nm (N/cc) 

370 470 570 670 770 870 970 

Time (s) 

20nm 60nm 

Figure 94: DMS500 60 nm and 20 nm Particle Number vs. Time for E55CRC-41 

tested at 56,000 lbs. 

Figure 95 shows the total number of particles and CO versus time. This plot shows the 

correlation between the two series. This kind of a relation is actually expected due to the 

fact that a large portion of particulate matter is elemental carbon (EC). 

Figure 96 shows the total number of particles in the 60 nm bin versus the total number of 

particles in the 20 nm bin. As can be seen, there is no clear correlation between the two 

size bins, although the envelope of the points is well defined. 

Figure 97 shows the total number of particles in the 20 nm bin versus the total hub power. 

There is no strong correlation between the two series. Figure 98 shows the total number 

of particles in the 60 nm bin versus the total hub power. Again, there is no strong 

correlation, suggesting that the particle formation cannot be attributed to engine load 

alone. 

111 
6.E+06 5.E-02 

4.E-02 

Total Particle Number (N/cc) 5.E+06 

4.E-02 

4.E+06 3.E-02 

3.E-02 

3.E+06 

2.E-02 

2.E+06 2.E-02 

1.E-02 

1.E+06 

5.E-03 

0.E+00 0.E+00 

370 470 570 670 770 870 970 

Time (s) 

Total Particle Number (N/cc) CO (g/s)

CO (g/s) 

Figure 95: DMS500 Total Number of Particles and CO vs. Time for E55CRC-41 

tested at 56,000 lbs. 

1.E+05

1.E+05

8.E+04

60nm (N/cc)

y = 0.1802x + 10464 6.E+04 

R2

 = 0.2195 

4.E+04 

2.E+04 

0.E+00 

0.E+00 5.E+04 1.E+05 2.E+05 2.E+05 3.E+05 

20nm (N/cc) 

Figure 96: DMS500 60 nm Particle Number vs. 20 nm Particle Number for 

E55CRC-41 tested at 56,000 lbs. 

112
20nm (N/cc) 

3.E+05 

2.E+05 

2.E+05 

1.E+05 

5.E+04 

0.E+00 

-350 -300 -250 -200 -150 -100 -50 0 50 100 150 200 

-5.E+04 

y = 247.9x + 23460

R2

 = 0.0874

-1.E+05 

Total Hub Power (hp) 

Figure 97: DMS500 20 nm Particle Number vs. Total Hub Power for E55CRC-41 

tested at 56,000 lbs. 

1.E+05 

1.E+05 

8.E+04 

60nm (N/cc) 

6.E+04 

4.E+04 

2.E+04 

0.E+00 

-350 -300 -250 -200 -150 -100 -50 0 50 100 150 200 

y = 99.18x + 13732 -2.E+04 

R2

 = 0.0953 

-4.E+04 

Total Hub Power (hp) 

Figure 98: DMS500 60 nm Particle Number vs. Total Hub Power for E55CRC-41 

tested at 56,000 lbs. 

113 
Figure 99 shows the size distribution of particles during acceleration and deceleration 

periods. During acceleration, a single mode distribution is observed where the peak is 

centered at around 100 nm. This is expected since during accelerations, accumulation 

mode particles are formed. For the deceleration region, a single mode distribution is seen. 

The peak is centered around 20 nm, and these are the nuclei mode particles. This mode is 

observed during deceleration periods, as the plot also shows. Number of Particles (N/cc)

3.E+04 

2.E+04 Acceleration 

Deceleration 

2.E+04 

1.E+04 

5.E+03 

0.E+00 

0 100 200 300 400 500 600 700 800 900 1000 

Diameter (nm) 

Figure 99: DMS500 size distribution of particles during acceleration and 

deceleration for E55CRC-41 tested at 56,000 lbs. 

E55CRC-42 

E55CRC-42 was a powered by a Caterpillar 3406, MY 1999 engine. Particle sizing and 

chemical speciation results are presented below for various modes of the HHDDT 

schedule. Figure 100 and Figure 101 present the particle size distribution for Idle and 

steady modes. 

A typical uni-modal size distribution was noted for the Idle mode for E55CRC-42 (Figure 

101) with a CMD of 40 nm and concentration of 1.3x105 particles/cc. In comparison to 

E55CRC-39 and E55CRC-40, the size distribution shifted towards a larger particle size 

for E55CRC-42 during the Idle Mode. In addition to the nuclei mode, the size distribution 

is also characterized by a mode with a CMD of 100 nm. 

114 
1.00E+01 

2.00E+04 

4.00E+04 

6.00E+04 

8.00E+04 

1.00E+05 

1.20E+05 

1.40E+05 

Particle Number Concentration (dN/dlogDp) #/cm^3 

10 100 1000 

Particle Diameter (nm) 

Figure 100: SMPS Particle Size Distribution for E55CRC-42 Operating on an Idle 

Mode 

1.00E+01 

2.00E+05 

4.00E+05 

6.00E+05 

8.00E+05 

1.00E+06 

1.20E+06 

Particle Number Concentration (dN/dlogDp) #/cm^3 

Steady State 

1.00E+01 

2.00E+04 

4.00E+04 

6.00E+04 

8.00E+04 

1.00E+05 

1.20E+05 

1.40E+05 

1.60E+05 

1.80E+05 

2.00E+05 

Particle Number Concentration (dN/dlogDp) #/cm^3 

Cruise 

Steady State 

Cruise3 

HHDDT_S 

10 100 1000 

Particle Diameter (nm) 

Figure 101: SMPS Particle Size distribution for E55CRC-42 operating on various 

steady cycles 

115 
The accumulation mode observed during the Idle could be due to an increase in elemental 

carbon emission when compared to the previous vehicles tested. During the Idle Mode, 

the elemental carbon emitted by E55CRC-39 and E55CRC-40 were 0.21 g/hour and 0.07 

g/hour, respectively and for E55CRC-42, the values were higher at 0.55 g/hour (Figure 

104). This increase in elemental carbon also increased the mass emission for the Idle 

mode at 1.34 g/hour (Figure 102). Mass emissions during Idle for E55CRC-39 and 40 

were 0.35 g/hour and 0.14 g/hour, respectively. Total volatile organic compounds emitted 

by E55CRC-42 during the Idle mode at 2.99 g/hour were much lower when compared 

with the Cruise mode at 6.04 g/hour (Appendix O: Figure O25 to O29). 

18 

g/hour 

16 

14 

12 

10 

8 

6 

4 

2 

0

Idle Cruise3 HHDDT_S

Figure 102: PM Mass Emissions for E55CRC-42 

Particle sizes measured during the steady state and Cruise mode were similar with a 

CMD of 93.6 nm, 98.39 nm and 93.71 nm for the steady state, normal Cruise and Highspeed Cruise Modes, respectively. Concentrations for the steady state mode were 6 times 

higher in magnitude as compared with both the Cruise Modes. Concentration drop for the 

Cruise mode could be due to a higher exhaust temperature. Sulfate emissions were higher 

during the Cruise mode at 0.54 g/hour when compared to Idle mode at 0.06 g/hour 

(Figure 104). Carbonaceous particles along with sulfates, and adsorbed of volatile and 

semi-volatile particles mostly constitute the nature of the particles emitted during the 

steady cycles. The total carbon in the idle mode PM is approximately evenly split 

between organic and elemental carbon. While the Idle Mode emissions are characterized 

by a distinct nuclei mode, the contribution of this fraction to the total PM mass emission 

rate is very small. 

116 
0.00 

0.10 

0.20 

0.30 

0.40 

0.50 

0.60 

0.70 

0.80 

0.90 

1.00 

Idle Trans Cruise 

CRC 42 

g/hour 

Soluble Calcium 

Soluble Potassium 

Soluble Magnesium 

Soluble Sodium 

Ammonium 

Sulfate 

Nitrate 

Nitrite 

Chloride 

Figure 103: Ion Composite Results for E55CRC-42 

g/hour 

18

16

14

12

10

8

6

4

2

0

Elemental Carbon 

Organic Carbon 

Idle Trans Cruise 

CRC 42

Figure 104: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-42 

117 
For E55CRC-42, DMS500 data on the UDDS, Cruise mode and HHDDT_S showed 

anomalous behavior (output spikes) but two repeat runs on the Transient mode agreed 

acceptably well, as shown in Figure 105. 

0.E+00 

5.E+05 

1.E+06 

2.E+06 

2.E+06 

3.E+06 

3.E+06 

Total Particle Number (N/cc) 

-100 

-80 

-60 

-40 

-20 

0 

20 

40 

Vehicle Speed (mph) 

0 100 200 300 400 500 600 

Time (s) 

TRANS3 (1) TRANS3 (2) Vehicle Speed 

Figure 105: DMS500 Total Number of Particles and Vehicle Speed vs. Time on 

Transient mode for E55CRC-42 tested at 56,000 lbs. 

E55CRC-43 

E55CRC-43 was a powered by a Detroit Diesel Series 60, MY 1994 engine. Particle 

sizing and chemical speciation results are presented below for various modes of the 

HHDDT schedule. Figure 106 and Figure 107 present the particle size distribution for 

Idle and steady modes. 

Particle size distribution for Idle Mode was unimodal with a CMD of 51.43 nm and a 

GSD of 1.44 which indicates a good distribution about the mean. Maximum 

concentration level was around 2.25x105

 particles/cm3. These particles are mostly 

accumulation mode particles as observed for E55CRC-42. Reasons for this accumulation 

mode are similar to those presented above for E55CRC-42. 

118 
Particle Number Concentration (dN/dlogDp) #/cm^3 

2.50E+05 

2.00E+05 

1.50E+05 

1.00E+05 

5.00E+04 

1.00E+01 

10 100 1000 

Particle Diameter (nm) 

Figure 106: SMPS Particle Size Distribution for E55CRC-43 Operating on an Idle 

Mode 

1.00E+01 

2.00E+04 

4.00E+04 

6.00E+04 

8.00E+04 

1.00E+05 

1.20E+05 

1.40E+05 

1.60E+05 

1.80E+05 

Particle Number Concentration (dN/dlogDp) #/cm^3

Crusie 

0.00E+00 

5.00E+05 

1.00E+06 

1.50E+06 

2.00E+06 

2.50E+06 

3.00E+06 

3.50E+06 

4.00E+06 

Particle Number Concentration (dN/dlogDp) #/cm^3

Steady state & HHDDT_S 

Steady State 

HHDDT_S 

Cruise3 

10 100 1000 

Particle Diameter (nm) 

Figure 107: SMPS Particle Size Distribution for E55CRC-43 Operating on Various 

Steady Cycles 

119 
0 

1 

2 

3 

4 

5 

6 

g/hour 

The total volatile organic compounds emitted by this particular vehicle were 2.28 g/hour 

for Idle and 3.39 g/hour for Cruise. Volatile compound emissions at Idle were 20% lower 

than E55CRC-42. A shift in the particle size was noted for the steady cycles. For the 

steady state and High-speed Cruise Modes, the GSD were 1.88 and 2.6, respectively, 

which is higher than the normal GSD which denotes a random distribution about the 

mean which can be clearly observed from Figure 107. The CMD noted for the steady 

state, normal Cruise and High-speed Cruise Modes were 54.32, 68.5 and 69.56 nm, 

respectively. It should be noted that in the case of a HHDDT_S or Cruise Mode scan, 

there is no assurance that the driver might not move the pedal and disturb the steady 

operation during SMPS scan. Elemental carbon emissions were very high during the 

Cruise Mode at 3.17 g/hour when compared to Idle Mode emissions at 0.25 g/hour. 

Organic carbon emissions were also higher during the Cruise mode at 6.15 g/hour when 

compared to Idle Mode emissions at 1.03 g/hour. 

Idle Cruise3 HHDDT_S 

Figure 108: PM Mass Emissions for E55CRC-43 

The increase in the particle size and concentration in the Cruise Modes is attributed to the 

very high increase in the elemental carbon emissions. A slight increase by 12% in the 

VOC emission was noted for the Cruise mode (Appendix O: Figure O37 to O41). An 

85% increase in the sulfate emission was noted for the Cruise mode (Figure 109). 

Calcium was also a major contributor to the inorganic species with an increase of 91% 

for the Cruise Mode. Calcium emissions are attributed to lubrication oil, since calcium is 

a major constituent in lube oil. Particles measured during the Cruise mode of this 

particular vehicle were primarily carbonaceous soot with heavy hydrocarbons adsorbed 

onto the surface. 

120 
0.00 

0.10 

0.20 

0.30 

0.40 

0.50 

0.60 

0.70 

0.80 

0.90 

1.00 

Idle Trans Cruise 

CRC 43 

g/hour 

Soluble Calcium 

Soluble Potassium 

Soluble Magnesium 

Soluble Sodium 

Ammonium 

Sulfate 

Nitrate 

Nitrite 

Chloride 

Figure 109: Ion Composite Results for E55CRC-43 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

Idle Trans Cruise 

CRC 43 

g/hour 

Elemental Carbon 

Organic Carbon 

Figure 110: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-43 

121 
DMS500 data were acquired for the Transient Mode, and are shown in Figure 111. 

0.E+00 

1.E+05 

2.E+05 

3.E+05 

4.E+05 

5.E+05 

6.E+05 

7.E+05 

8.E+05 

9.E+05 

1.E+06 

Total Particle Number (N/cc) 

0 

10 

20 

30 

40 

50 

60 

Vehicle Speed (mph) 

0 100 200 300 400 500 600 

Time (s) 

TRANS3 (1) Vehicle Speed 

Figure 111: DMS500 Total Number concentration of Particles and Vehicle Speed vs. 

Time for E55CRC-43 tested at 56,000 lbs. 

E55CRC-44 

E55CRC-44 was a powered by a Caterpillar 3406, MY 1989 engine. Particle sizing and 

chemical speciation results are presented below for various modes of the HHDDT 

schedule. Figure 112 and Figure 113 present the particle size distribution for Idle and 

steady modes. 

A bimodal distribution was noted for this particular vehicle during the Idle Mode, with 

one nano-particle peak at 26.9 nm and another accumulation mode peak at 122 nm. It 

should be noted that the Idle Mode is characterized by relatively lower PM number 

concentrations. The only other vehicle where a bimodal distribution was observed was 

E55CRC-39 which was a 2004 year model engine. The reason for the bimodal 

distribution for E55CRC-39 was due to high levels of volatile compounds and elemental 

carbon during the Idle Mode. The elemental carbon contributed to the accumulation 

mode. 

122 
4.50E+04 

0.00E+00 

5.00E+03 

1.00E+04 

1.50E+04 

2.00E+04 

2.50E+04 

3.00E+04 

3.50E+04 

4.00E+04 

Particle Number Concentration (dN/dlogDp) #/cm^3 

10 100 1000 

Particle Diameter (nm) 

Figure 112: SMPS Particle Size Distribution for E55CRC-44 Operating on an Idle 

Mode 

1.00E+05 

Particle Number Concentration (dN/dlogDp) #/cm^3 9.00E+04 

8.00E+04 

7.00E+04 

6.00E+04 

5.00E+04 

4.00E+04 

3.00E+04 

2.00E+04 

1.00E+04 

1.00E+01 

10 100 1000 

Particle Diameter (nm) 

Steady State 

Cruise3 

HHDDT_S 

Figure 113: SMPS Particle Size Distribution for E55CRC-44 Operating on Various 

Steady Cycles 

123 
The precursors of the nano-particle emissions could be traced back to lube oil based 

volatile hydro-carbons, and the lower exhaust temperature during exhaust mode. Again, 

nano-particle peak could be due to high emissions of semi-volatile compounds (Appendix 

O: Figure O54 and O55). The total volatile compound emissions for this vehicle were 

25% higher than E55CRC-43 and 35% higher than E55CRC-40. Further analysis yields 

that aromatic emissions during the Idle Mode, especially benzene were prominent for 

E55CRC-39 and E55CRC-44 when compared with the rest of the vehicles in the study 

(Appendix O: Figure O53). The accumulation mode in the Idle was attributed to the 

presence of carbonaceous agglomerates, with elemental carbon emission during the Idle 

mode being the highest among all the vehicles at 1.22 g/hour. 

30 

g/hour 

25 

20 

15 

10 

5 

0 

Idle Cruise3 HHDDT_S 

Figure 114: PM Mass Emissions for E55CRC-44 

The steady state particle size distributions were compatible with vehicle speed. Particle 

concentrations were increasing, though minimally, with increasing speed without much 

variation in the particle size. The count median diameter for the steady state, normal 

Cruise and High-speed Cruise were 173, 166 and 178 nm, respectively. Mass emissions 

were highest during the Cruise and High-speed Cruise Modes when compared to other 

vehicles (Figure 114). Elemental carbon which is basically soot was noted to be the 

highest among all the vehicles during the Cruise mode (Figure 116) was also a major 

contributor to the mass emission. This would also contribute to low saturation ratios; 

hence, the absence of nano-particles. Sulfate emissions were among the lowest when 

compared with all other vehicles (Figure 115). Results from these data suggest that the 

fine particles measured during the Cruise mode were mostly solid carbonaceous particles. 

124 
0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

Idle Trans Cruise 

CRC 44 

g/hour 

Soluble Calcium 

Soluble Potassium 

Soluble Magnesium 

Soluble Sodium 

Ammonium 

Sulfate 

Nitrate 

Nitrite 

Chloride 

Figure 115: Ion Composite Results for E55CRC-44 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

Idle Trans Cruise 

CRC 44 

g/hour 

Elemental Carbon 

Organic Carbon 

Figure 116: Elemental Carbon and Organic Carbon PM Analysis for E55CRC-44 

No DMS500 data are available for E55CRC-44. 

125 
CONCLUSIONS, NONREGULATED SPECIES 

Size distributions of PM from the six trucks were selected for non-regulated emissions 

measurement. These were acquired using a Scanning Mobility Particle Sizer (SMPS), as 

well as a Differential Mobility Spectrometer, Model 500 (DMS500), which was a newly 

released instrument. The SMPS was fed dilute exhaust from a mini-dilution tunnel, using 

a dilution ratio of thirty, while the DMS used the main dilution tunnel of the TransLab. 

The SMPS detected a bimodal distribution with a nuclei mode for Idle operation of one 

2004 MY truck (E55CRC-40), and the DMS 500 detected both the nuclei mode and 

accumulation mode during deceleration on this truck. The nuclei mode was not evident 

under load for E55CRC-40. The other 2004 MY truck had only one mode, with a very 

low particle count on Idle. A 1989 MY truck had a bimodal Idle distribution, but the 

remaining HHDDT were unimodal. Comprehensive data were acquired for steady 

operation using the SMPS on all trucks, and the DMS500 acquired transient distributions 

for four of the trucks. 

Chemical speciation was performed on the six trucks, with exhaust from the TransLab 

tunnel fed to a residence time chamber of the DRI. Data were acquired for methane and 

volatile organic compounds using a canister and a field gas chromatograph. Semi-volatile 

organic compounds were captured in PUF/XAD media and PM soluble fraction was 

captured on TIGF filters, and these were extracted and analyzed at the DRI laboratory. 

Carbonyls were captured using DNPH cartridges, nitrosamines in Thermosorb cartridges. 

Ions and Elemental/Organic carbon (EC/OC) split were determined from quartz filters. 

Results from the speciation data are legion, and examples include the fact that the EC/OC 

split differed substantially on Idle between the two 2004 MY trucks equipped with EGR, 

and that the ion and metal analyses varied widely between trucks. 

Summarized below in a graphical form are the emissions of elemental carbon (as a 

percentage of total), inorganic ionic species, lubrication oil-based elemental emissions, 

and engine wear emissions in Figure 117 through Figure 120, respectively. Figure 117 

shows that except for idle operation, the elemental carbon constitutes a significant portion 

of total carbon emissions. Transient operation, in particular, yields in excess of 60% of 

total carbon as elemental carbon. Total PM mass emissions, as discussed in the text, are 

the highest for the Transient mode, followed by Cruise, and then Idle. Total PM mass 

emissions under Idle are significantly lower than the Transient and Cruise modes. 

However, in terms of total carbon mass emission rates, the Cruise mode emits the highest 

levels, followed by the Transient mode of operation. The Idle mode is characterized by 

significantly lower rates of total carbon mass emissions. 

The mass emissions rates of sulfates dominate the ionic species in the cruise and transient 

modes. The only other species of significance were nitrates and ammonium. 

Total particulate matter comprises of elemental carbons, organic carbon, engine wear 

elements, lube oil based ash components, water, and ionic species. Most of these 

emissions are a result of un-burnt fuel and lubricating oil. Apart from severe engine wear 

(abrasive wear) on boundary lubricated surfaces (cam lobe wear, tappet polishing, 

126 
rocker/crosshead wear, ring wear at top and bottom reversal locations, etc.), oil control is 

extremely critical from an emissions point of view. Based upon prior studies by Lapin et 

al.19 and Gautam et al.14, it may be hypothesized that products of lubricating oil 

combustion (partial) result in higher potential mutagenicity of exhaust emissions, and that 

lubricating oil contributes to high concentrations of nanoparticles in exhaust emissions1. 

Lubricating oil enters the combustion chamber through the following routes: as blow-by 

gas, leakage past valve stem seals, piston rings and vaporisation from the cylinder liner 

walls and combustion space20. 

100% 

90% 

80% 

70% 

60% 

50% 

40% 

30% 

20% 

10% 

0% 

CRC 39 CRC 40 CRC 41 CRC 42 CRC 43 CRC 44 

Idle 

Transient 

Cruise 

Elemental Carbon Fraction 

Figure 117: Elemental Carbon Emissions (Percentage of Total Carbon) 

127 
Emissions g/hour 

2.50 

2.00 

1.50 

1.00 

0.50 

0.00 

Idle

Trans

Cruise

Idle

Trans

Cruise

MD Idle

MD Trans

MD Cruise

Idle

Trans

Cruise

Idle

Trans

Cruise

Idle

Trans

Cruise 

CRC 39 CRC 40 CRC 41 CRC 42 CRC 43 CRC 44 

NH4+ 

SO4-2 

NO3-

NO2-

ClFigure 118: Inorganic Ionic Species Emissions 

Figure 119 shows the mass emission rates of lubricating oil based elements from the test 

engines. These elements contribute to the total PM mass. Again, sulfur and calcium are 

the principal pollutants that can be traced back to the lubricating oil. In the older engines 

(CRC-42 and CRC-43) phosphorus emissions were significantly higher than those from 

other newer engines. 

Figure 120 shows a summary of mass emissions rates of engine wear elements. Among 

these elements, iron contributed the most to the total PM emissions under all modes of 

operation. Of course, in terms of mass emission rates, iron emissions were the higher in 

the Transient and Cruise Modes of operation. 

128 
Emissions, g/hour 

0.70 

0.60 

0.50 

0.40 

0.30 

0.20 

0.10 

0.00 

Idle

Trans

Cruise

Idle

Trans

Cruise

MD Idle

MD Trans

MD Cruise

Idle

Trans

Cruise

Idle

Trans

Cruise 

CRC 39 CRC 40 CRC 41 CRC 42 CRC 43 

Pb 

Mo 

Ca 

S 

P 

Mg 

Figure 119: Lubrication Oil Emissions 

129 
Emissions, g/hour 

0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

Idle

Trans

Cruise

Idle

Trans

Cruise

MD Idle

MD Trans

MD Cruise

Idle

Trans

Cruise

Idle

Trans

Cruise 

CRC 39 CRC 40 CRC 41 CRC 42 CRC 43 

Zn 

Cu 

Fe 

Figure 120: Engine Wear Emissions 

130 
TAMPERING, MALMAINTENANCE AND REFLASH VEHICLES 

The E-55/59 program sought to identify high emitters, or vehicles that showed evidence 

of T&M. Vehicles were identified as T&M candidates either from a pretest inspection or 

from measurement of emissions that were high relative to developed threshold criteria. 

The criteria for declaring NOx to be high were developed using NOx/CO2 ratios from 

certification data, and the PM criteria were developed as PM/CO2 ratios considering 

Phase 1 fleet data statistically. The program plan provided that high emitters could be 

subjected to repair, followed by re-testing of emissions. In addition, during Phase 1.5 of 

the program, three truck engine controllers were reflashed. These trucks had MY that 

suggested that they may have off-cycle control strategies in the controller, and the effect 

of reflashing to a lower NOx strategy was assessed. 

Diesel vehicle deterioration and inspection and maintenance have been discussed 

previously by Weaver and Klausmeier21 and Weaver et al.22, but few data exist either on 

the incidence of high emitters or the effect of repair on truck emissions. The website 

http://www.driveclean.com/downloads/2003_HDV_Report.pdf provides modeling 

information as part of the Ontario, Canada, Drive Clean program. Yanowitz and coworkers1,23 have presented the change of emissions with truck MY, but this cannot be 

uniquely ascribed to deterioration of emissions. 

T&M Criteria 

An objective of the E55/59 program was to quantify the influence of T&M on heavy-duty 

vehicle emissions. This was achieved by identifying test vehicles that qualified as 

candidates for the study, using two separate pathways: 

1. Vehicle Inspection: Vehicles were considered candidates if they showed evidence 

of T&M that may affect emissions. The evidence might be found at the time of 

vehicle inspection, or revealed during the test procedure. A vehicle might qualify 

for repair and retest as a result of inspection, but might prove to yield emissions at 

a level below that considered high or gross. 

2. High Emissions Levels: Vehicles were considered as candidates if they showed 

emissions levels that were high, or gross, relative to expected levels for those 

vehicles. It was not required that visual T&M was evident for these high emitting 

vehicles. 

Determination of Candidates from Vehicle Inspection 

The vehicles from the program in Phase 1 of E-55/59 were recruited either directly by 

WVU or with the aid of the California Trucking Association. In subsequent phases the 

vehicles were recruited by WVU alone. Vehicles were transported to the test site in 

Riverside, CA. Each vehicle was inspected to identify any of the following tampering or 

malmaintenance items. 

131 
1. Cleanliness of air filter. 

2. Integrity of lines between turbocharger an intercooler. 

3. Integrity of lines between intercooler and engine intake. 

4. Presence of manifold air pressure sensor (MAP) and integrity of wiring 

connection to MAP (This applies to most electronic engines). 

5. Presence of manifold air temperature sensor (MAT) and integrity of wiring 

connection to MAT (This applies to most electronic engines). 

6. Integrity of wiring harness and connections to engine controller (This applies to 

all electronic engines where the controller is visible). 

7. Integrity of wastegate/boost control on turbocharger (This applies to many newer 

electronic engines). 

8. Condition of intercooler, though in many cases the core will not be visible 

because it is sandwiched between the air conditioner and radiator. 

9. Integrity of linkages and fuel lines surrounding fuel injection pump, or breakage 

of seal on fuel injection pump (This applies to older mechanical engines). 

10. Correctness of fuel (not dyed off-road fuel) in tank, where practical. 

If inspection identified a technical or maintenance concern that might affect emissions, 

the vehicle immediately became a “T&M candidate,” which could potentially be 

subjected to repair and retest. 

Determination of T&M Candidate from Emissions 

In the study, vehicles were potential candidates for repair and retest if they were 

identified as high emitters. The term “high emitters” was intended to represent vehicles 

emitting PM or NOx at gross levels; that is, levels, which are substantially higher than 

would be expected from a statistical sample of similar, correctly operating vehicles. In E55/59 the criteria for high emissions were developed during Phase 1, and were applied in 

this form to all phases of the program. 

High HHDDT emitters of NOx were identified in the following fashion. NOx emissions 

were known to be dependent on engine power (and hence fuel consumed), but relatively 

insensitive to the transient nature of tests unless the engine control included off-cycle 

strategies. In many cases NOx varies in a linear fashion with brake power and in direct 

proportion to fuel consumed24,25. It is therefore reasonable to compare NOx/CO2 ratios for 

different tests, although the investigators were aware of the way in which off-cycle 

engine timing could elevate NOx levels. Cycle effects on NOx emissions have recently 

been discussed by Clark et al.26 and are addressed in a paper by Yanowitz et al.1. 

Table 6 provides the U.S. certification levels for engines. The “2003+” value for NOx 

recognizes that the 2004 regulations were brought forward from 2004 for the 

manufacturer according to the Consent Decree, and approximates the NOx level at 2.0 

g/bhp-hr. Ratios by mass of NOx/CO2 implied by the certification can be determined if a 

132 
typical Federal Test Procedure certification level of 550 g/bhp-hr (738 g/kw-hr) of CO2 is 

assumed. When a normally operating engine is exercised through cycles other than the 

certification cycle as in the case of the E-55/59 program, NOx/CO2 ratios may deviate 

from the certification NOx/CO2 ratios for two reasons. Firstly, the engine timing is not 

uniform over the whole operating envelope, and may differ slightly between the 

certification envelope and remainder of the operation envelope. This may cause modest 

increases (or decreases) in the NOx/CO2 ratio. This is likely to have a greater effect in 

electronic engines or in mechanical engines without variable injection timing. Secondly, 

many electronic engines have off-cycle NOx missions as a result of employing a separate 

timing map during some instances of real-world operation. This is known to raise NOx by 

a factor of up to 2.527, corresponding to 10 to 12 g/bhp-hr (13 to 16 g/kw-hr) NOx for 

engines certified to 5 g/bhp-hr (6.7 g/kw-hr), even at high load conditions. Engines 

operating off-cycle are not considered to fit the T&M criteria because they are in original 

condition and need not be reconfigured except at the time of rebuild, under rules 

prevailing during the time of the E-55/59 program. Off-cycle emissions of this kind occur 

solely with electronic engines. 

In the E-55/59 program, emissions values used to determine whether a vehicle was a high 

NOx or PM emitter were taken from the transient and cruise modes of the HHDDT 

schedule. This schedule was created and evaluated by the California Air Resources Board 

and WVU in a previous cooperative effort28,29. There were at least two repeat runs of the 

transient and cruise modes for each vehicle. Data were acquired at a test weight of 56,000 

lbs. (25,402 kg). A vehicle (1) had to show high NOx in two transient runs to be 

considered a high NOx emitter on the transient mode, or (2) had to show high NOx in two 

cruise runs to be considered a high NOx emitter on the cruise mode. Similarly, the vehicle 

(3) had to emit high PM in two transient runs conducted to be considered a high PM 

emitter on the Transient or (4) produce high PM in two cruise runs conducted to be 

considered a high PM emitter on the transient mode. The vehicle was considered a high 

emitter and as a candidate for repair and retest under any one of these four circumstances. 

In order to avoid capturing “off-cycle” emissions vehicles as T&M vehicles, the 

NOx/CO2 ratio for identifying a candidate vehicle was set at three times the certification 

NOx/CO2 ratio for electronic engines. For mechanically injected engines, the criterion 

NOx/CO2 ratio was set at twice the certification NOx/CO2 ratio. 

Table 19 shows the resulting emissions level criteria used to declare a truck to be a high 

NOx emitter. Table 19 uses California certification values and vehicle MY as a basis. 

In cases where vehicles pre-dated the advent of brake-specific emissions standards for 

values of NOx emissions, a value of 10g/bhp-hr (13.4 g/kw-hr) was used as if it were a 

certification standard in identifying high NOx emitters. Early vehicles all have 

mechanically controlled engines, so that the failure criteria shown below were based on a 

NOx/CO2 ratio for these early vehicles using twice this assumed level; i.e., 20 g/bhp-hr 

(26.8 g/kw-hr). 

133 
Table 19: Emissions level criteria used to declare a truck to be a high NOx emitter. 

California 

NOx 

g/bhp-hr 

(g/kw-hr) 

CO2 

g/bhp-hr 

(g/kw-hr) 

NOx / CO2 

Certification 

Ratio 

Mechanical 

High Emitter 

Criterion 

(Cert x 2) 

NOx/CO2 

Electronic 

High Emitter 

Criterion 

(Cert x 3) 

NOx/CO2 

1987-90 6 (8) 550 (738) 0.0109 0.0218 0.0327 

1991-93 5 (6.7) 550 (738) 0.0091 0.0182 0.0273 

1994+ 5 (6.7) 550 (738) 0.0091 0.0182 0.0273 

1994-95 5 (6.7) 550 (738) 0.0091 0.0182 0.0273 

1996+ 4 (5.4) 550 (738) 0.0073 0.0145 0.0218 

No detailed criteria were developed in Phases 2 and 3 for the MHDT: the researchers 

used their own judgment in reviewing the NOx emissions data to determine if a truck 

should be considered as an MHDT T&M candidate. One MHDT, CRC-57, revealed a 

cooling malfunction on the dynamometer and was the only MHDT that was identified as 

a T&M candidate. CRC-57 was not repaired, and is discussed in a separate section below. 

Determining high HHDDT PM emitters was more difficult than determining high NOx 

emitters because PM is highly sensitive to the transient content of a cycle and therefore 

cannot be projected for different cycles using certification data26,30,31. PM emissions drop 

only very slightly as a result of off-cycle operation, so off-cycle operation need not be 

considered with regard to PM. To determine PM high emitters, the data for each of the 25 

trucks (all HHDDT) in Phase 1 of the program in the transient and cruise modes were 

expressed as ratios of PM/CO2. This ratio was then divided by the PM/CO2 ratio for the 

certification standards for that engine MY, assuming a level of 550g/bhp-hr (738 g/kwhr) of CO2 for certification. This “criterion ratio” calculation is shown below. The 

criterion ratio for vehicles that pre-date the PM transient test (FTP) standards in their MY 

was based on a PM pseudo-standard of 1g/bhp-hr (1.3 g/kw-hr) PM. 

Consider an example using actual data from a vehicle with an engine manufactured in 

1999 or 2000 during the Transient mode of the HHDDT schedule: 

Actual data for Transient Mode 

PM = 0.4435 g/mile (0.2756 g/km) 

CO2 = 2599 g/mile (1615 g/km) 

(PM/CO2)Trans = 0.000171 

134 
1999 – 2000 Certification 

PM = 0.1 g/bhp-hr (0.134 g/kw-hr) 

CO2 = 550 g/bhp-hr (738 g/kw-hr) 

(PM/CO2)Cert = 0.000182 

Criterion _ Ratio = (PM / CO2 )Trans = 0.939

(PM / CO2 )Cert

For a vehicle to be identified as a high PM emitter, this criterion ratio described above 

had to be significantly higher than the criterion ratios for typical vehicles in the fleet. In 

this case the term “typical vehicles” refers to both normal and high emitters. Note that the 

inclusion of certification levels in the criterion ratio does allow for influence of changing 

technology in identifying high PM emitters. To achieve this identification goal, it was 

necessary to build a database of PM criterion ratios from the initial vehicles that were 

tested, and determine the average and standard deviation of those criterion ratios. Any 

truck that was two standard deviations above the average on two runs of the Transient 

mode was deemed a high PM emitter for the transient mode. Any truck that was two 

standard deviations above the average on two runs of the Cruise mode was deemed a high 

PM emitter for the cruise mode. Since the database of vehicles tested evolved over the 

duration of the program, it was possible that the statistics would change over time, but no 

remedy for this change was possible. It was noted that in this methodology vehicles with 

high emissions on the Transient mode but not on the Cruise mode would most likely be 

“puffers,” caused by turbocharger damage or fuelling limit tampering, while those that 

were found to be high using the cruise criterion (whether they are high on the transient or 

not) were likely to be continuous smokers at high load. The statistical criteria for high 

PM emitters were finalized in Phase 1 and used to identify for high emitters of PM in 

subsequent phases. 

No detailed PM high emitter criteria were developed in Phases 2 and 3 for the MHDT: 

the researchers used their own judgment in reviewing the PM emissions data to determine 

if a truck should be considered as an MHDT T&M candidate. 

Once a vehicle was identified as a high NOx or PM emitter, it was treated in the same 

way as a vehicle that was found to have evidence of T&M upon inspection. 

Results: T&M by Inspection 

All vehicles were subjected to both inspection and emissions characterization. One 

vehicle, E55CRC-21, was found to have a dirty air filter by inspection, and became a 

T&M candidate. The repair and retest data of E55CRC-21 are presented in a separate 

section below. Two other vehicles, E55CRC-16 and E55CRC-45, were visually identified 

as prodigious smokers. E55CRC-16 subsequently was found to have emissions 

management components removed, but it was treated in the program as having high PM 

emissions by measurement. No other vehicles were considered as T&M vehicles by 

inspection. However, in Phase 3 one HHDDT brought to the site was visibly in poor 

repair, ceased running after arrival, and was not tested. 

135 
0.000 

0.002 

0.004 

0.006 

0.008 

0.010 

0.012 

0.014 

0.016 

0.018 

0.020 

Transient Mode (NOx/CO2) 

Expected 

High 

Verifying the Criteria in Phase 1: NOx Analysis 

Figure 121 shows the NOx/CO2 ratios for each run on the twenty-five Phase 1 vehicles, 

for both Transient and Cruise Modes. Vehicle E55CRC-10 was the only vehicle to be 

identified as a “high” NOx emitter according to the T&M plan. 

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 

Cruise Mode (NOx/CO2) 

Figure 121: NOx/CO2 ratios for each run on the 25 vehicles, both transient and 

cruise. One vehicle was found to have high NOx emissions on two runs of the cruise 

mode 

The high criterion for vehicle E55CRC-10 was 0.0218 (See Table 2). Since the vehicle 

greatly exceeded the criterion, the data were more closely investigated. The fact that NOx 

emissions were high on cruise but low on transient operation was an indicator that offcycle emissions were the cause. To investigate these further, NOx emissions were plotted 

continuously against the power. Figure 122 shows the NOx emissions versus dispersed 

power plot for both the cruise and transient modes of the new ARB HHDDT schedule for 

E55CRC-10. Dispersed power is power that has been diffused in time to provide a closer 

correlation with measured emissions32. In preparing plots of this kind it is important to 

shift the emissions in time to match the power, because of measurement delay: this is 

achieved using cross correlation, because it is known that power and NOx vary in 

sympathy. It is evident that the vehicle exhibited classical “off-cycle” behavior with the 

bulk of the transient emissions at a low NOx level, and the bulk of the cruise emissions at 

a high NOx level. However, whereas most trucks yield off-cycle values (in brake-specific 

terms) that are about 2.5 times the “on-cycle” values, this truck had values exceeding 

three times. A contribution to this high ratio was its low original standard of 4 g/bhp-hr 

136 
(5.36 g/kw-hr). The investigators believed that the high NOx was simply an original offcycle phenomenon, and would therefore not be remedied by any repair. This vehicle was 

therefore not selected as a T&M vehicle, but was selected for reflash of its controller and 

termed a Reflash Vehicle. 

The finding that the high NOx emissions of E55CRC-10 were not due to a T&M cause 

suggested that it would be difficult to identify high NOx emitters as T&M candidates if 

they had electronic engine controllers that caused off-cycle emissions. In Phase 1.5 of the 

program, rather than seeking high NOx emitters by the criterion, three trucks with 

electronic engine control were selected directly for reflash and retest. The results for 

these three trucks, which coincidentally included a T&M vehicle (E55CRC-28), are 

treated in a separate section below. 

1.4 

1.2 

1.0 

0.8 

0.6 Cruise 

Transient 

0.4 

0.2 

0.0 

0 50 100 150 200 250 300 350 

Dispersed and Time Aligned Axle Horsepower (ahp) 

Figure 122: NOx emissions plotted against the dispersed and time aligned power for 

vehicle E55CRC-10. Most emissions during the Cruise mode were at an off-cycle 

level. The vehicle was targeted for Reflash as a result of these data. 

Verifying the Criteria in Phase 1: PM Analysis 

Figure 123 presents the average value of PM/CO2 ratios for Cruise mode operation of 

each Phase 1 HHDDT, and Figure 124 presents the average value of PM/CO2 ratios for 

the Transient Mode operation of each vehicle. These values were then converted to 

criterion ratios according to the T&M methodology described above. It was found that 

the average criterion ratio for the Transient Mode was 1.2736 with a standard deviation 

of 1.1486. It was found that the average criterion ratio for the cruise cycle was 0.5207 

with a standard deviation of 0.3567. These data suggest that if trucks were as “clean” as NOx Emissions (g/s)

137 
1

2

345

PM / CO2 Ratio 

when they were certified using the FTP, the Transient Cycle elicited higher brakespecific PM than the FTP, while the cruise cycle exhibited lower PM than the FTP. This 

is to be expected noting the relative transient content of the Transient and Cruise 

Modes29,33 and the fact that transient behavior usually elicits higher PM production. 

0.010 

0.009 

0.008 

0.007 

0.006 

0.005 

0.004 

0.003 

0.002 

0.001 

0.000 

E55CRC-1E55CRC-2E55CRC-3E55CRC-4E55CRC-5E55CRC-6E55CRC-7E55CRC-8E55CRC-9

E55CRC-10E55CRC-11E55CRC-12E55CRC-13E55CRC-14E55CRC-15E55CRC-16E55CRC-17E55CRC-18E55CRC-19E55CRC-20E55CRC-2E55CRC- 2E55CRC-2E55CRC-2E55CRC-2 

Figure 123: PM/CO2 ratios for Cruise Mode operation of average value for each 

vehicle. There are two runs each for E55CRC-1 to -13, and three runs each for 

E55CRC-14 to -25. 

138 
1

2

345

PM / CO2 Ratio 

0.006 

0.005 

0.004 

0.003 

0.002 

0.001 

0.000 

E55CRC-1E55CRC-2E55CRC-3E55CRC-4E55CRC-5E55CRC-6E55CRC-7E55CRC-8E55CRC-9

E55CRC-10E55CRC-11E55CRC-12E55CRC-13E55CRC-14E55CRC-15E55CRC-16E55CRC-17E55CRC-18E55CRC-19E55CRC-20E55CRC-2E55CRC- 2E55CRC-2E55CRC-2E55CRC-2 

139 

Figure 124: PM/CO2 ratios for the Transient Mode operation of average value for 

each vehicle. There are 2 runs each for E55CRC-1 to -13, 3 runs each for E55CRC14 to -25. One run for E55CRC-20 was anomalous low, but no cause was evident. 

One occurrence 

from each of 3 

different trucks 

Figure 125 shows the occurrence of criterion ratios by bin for the Transient Mode, where 

the bins are described in 

Occurences 2 21 19 7 9 1 1 3 

less than -

1 stdev 

-1 to -0.5 

stdev 

-0.5 stdev 

to avg 

avg to 0.5 

stdev 

0.5 to 1 

stdev 

1 to 1.5 

stdev 

1.5 to 2 

stdev 

greater 

than 2 

stdev 
Table 20. The resulting PM/CO2 ratios for each transient run identify E55CRC-6 with 

high emissions on one run of the transient test. 

Figure 126 shows the occurrence of criterion ratios by bin for the Cruise Mode, where the 

bins are described in Table 21. Only one run for vehicle E55CRC-6, for the transient 

case, fell outside of the two standard deviation limits so that this run represented high 

emissions. The other run for the Transient Mode case for E55CRC-6 lay between 1.5 and 

2 standard deviations above the average and so was not statistically high at the 95% level. 

Therefore, since both runs did not indicate high emissions, E55CRC-6 was not designated 

as a high emitter based on population statistics. E55CRC-8 and E55CRC-15 were 

similarly behaved. 

One occurrence 

from each of 3 

different trucks 

greater less than - -1 to -0.5 -0.5 stdev avg to 0.5 0.5 to 1 1 to 1.5 1.5 to 2 than 2 1 stdev stdev to avg stdev stdev stdev stdev stdev 

Occurences 2 21 19 7 9 1 1 3

Figure 125: Occurrence of criterion ratios by bin for the Laden Transient Mode

(PM/CO2). E55CRC-16 was not included in this analysis, because it was an extreme 

outlier. 

Table 20: Definition of criterion ratios by bin for the Laden Transient Mode: see 

Figure 125. 

140 
Bin description Bin Range 

less than -1 stdev less than 0.125 

-0.5 to -1 stdev 0.125 to 0.699 

-0.5 stdev to avg 0.699 to 1.274 

avg to 0.5 stdev 1.274 to 1.848 

0.5 to 1 stdev 1.848 to 2.422 

1 to 1.5 stdev 2.422 to 2.997 

1.5 to 2 stdev 2.997 to 3.571 

greater than 2 stdev greater than 3.571 

E55CRC-9 high both tests 

E55CRC-15 high on one test 

E55CRC-20 high on one test 

greater less than - -1 to -0.5 -0.5 stdev avg to 0.5 0.5 to 1 1 to 1.5 1.5 to 2 than 2 1 stdev stdev to avg stdev stdev stdev stdev stdev 

Occurences 3 23 11 12 6 2 2 4

Figure 126: Occurrence of criterion ratios by bin for the Laden Cruise mode 

(PM/CO2). E55CRC-16 was not included in this analysis because it was an extreme 

outliner. 

Table 21: Definition of criterion by bin for the Laden Cruise Mode: See Figure 126. 

141 
Bin Description Bin Range 

less than -1 stdev less than 0.164 

-0.5 to -1 stdev 0.164 to 0.342 

-0.5 stdev to avg 0.343 to 0.521 

avg to 0.5 stdev 0.521 to 0.699 

0.5 to 1 stdev 0.699 to 0.878 

1 to 1.5 stdev 0.878 to 1.056 

1.5 to 2 stdev 1.056 to 1.234 

greater than 2 stdev greater than 1.234 

The resulting PM/CO2 ratios for each cruise run identified E55CRC-9 as having high 

emissions on two cruise runs. E55CRC-9 was therefore designated as a high emitter and 

was a potential T&M candidate. The cause of the high PM emissions was not obvious, 

but may have been due to engine wear. Repairs in this case would be costly. There were 

several potential candidate T&M vehicles that had arisen at the time the E55CRC-9 was 

discussed by the researchers, and insufficient support to address them all. A sponsor 

decision was not to pursue E55CRC-9 for T&M repair and retest. E55CRC-20 showed 

high PM emissions on only one Cruise mode run and was therefore not designated as a 

high emitter. 

The PM emissions of E55CRC-16 were prodigious and it exhibited high PM emissions 

by all criteria on both Transient and Cruise Modes. It was selected as a T&M vehicle, and 

is discussed in a separate subsection below. Because the values were so high that they 

would skew the results, the E55CRC-16 results were not considered when calculating the 

“expected”/“high” statistical criteria. 

It is of interest to note that E55CRC-16 was most likely puffing because its Transient 

Mode PM emissions were high but Cruise Mode PM emissions were modest in contrast 

to E55CRC-9, which showed the opposite trend. Data also confirmed the visual 

observation of high PM output from vehicle E55CRC-16. E55CRC-16 was designated as 

a T&M candidate and is discussed in a separate subsection below. E55CRC-21 became a 

T&M vehicle by inspection of its dirty air filter, but was not a high PM emitter by test 

data criteria. 

The criteria for PM high emitters was finalized in Phase 1, and applied to HHDDT in 

subsequent phases. After Phase 1, some HHDDT in the program were only subjected to 

one run of each mode: the criterion that the vehicle must have two high values in the 

Transient mode or two high values in the Cruise mode could not be applied to those 

vehicles. It revealed in Phase 1.5 that E55CRC-28 was a high PM emitter in Phase 1.5 

and that E55CRC-45 was a high PM emitter in Phase 2. 

Criteria ratios for all phases 

Show the T&M criteria for all of the HHDDT vehicles examined in this study where 

“high” NOx and PM emitters, as identified by the previously discussed methodology, are 

highlighted in these tables. Only initial test data, not including any re-test data, were used 

142 
in determining the average and standard deviations in the particulate matter calculations. 

CRC-16, a gross PM emitter, was not included in the statistical calculations either. 

143 
Table 22: T&M Determination Data for the HHDDT Vehicles over the Cruise Mode 

Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-1 1994 0.0184 0.0091 3 0.68 0.000075 0.00018 0.4128 

E55CRC-1 1994 0.0204 0.0091 3 0.75 0.000081 0.00018 0.4441 

E55CRC-2 1995 0.0129 0.0091 3 0.47 0.000099 0.00018 0.5470 

E55CRC-2 1995 0.0132 0.0091 3 0.48 0.000093 0.00018 0.5124 

E55CRC-3 1985 0.0057 0.0093 2 0.31 0.000434 0.00182 0.2389 

E55CRC-3 1985 0.0050 0.0093 2 0.27 0.000419 0.00182 0.2302 

E55CRC-4 1999 0.0107 0.0073 3 0.49 0.000131 0.00018 0.7191 

E55CRC-4 1999 0.0114 0.0073 3 0.52 0.000150 0.00018 0.8250 

E55CRC-5 2000 0.0120 0.0073 3 0.55 0.000149 0.00018 0.8213 

E55CRC-5 2000 0.0147 0.0073 3 0.67 0.000146 0.00018 0.8048 

E55CRC-6 1995 0.0188 0.0091 3 0.69 0.000172 0.00018 0.9452 

E55CRC-6 1995 0.0158 0.0091 3 0.58 0.000181 0.00018 0.9951 

E55CRC-7 1990 0.0107 0.0109 3 0.33 0.000272 0.00109 0.2497 

E55CRC-7 1990 0.0118 0.0109 3 0.36 0.000254 0.00109 0.2332 

E55CRC-8 1996 0.0177 0.0091 3 0.65 0.000144 0.00018 0.7916 

E55CRC-8 1996 0.0210 0.0091 3 0.77 0.000148 0.00018 0.8128 

E55CRC-9 1998 0.0155 0.0073 3 0.71 0.000278 0.00018 1.5302 

E55CRC-9 1998 0.0157 0.0073 3 0.72 0.000262 0.00018 1.4402 

E55CRC-10 1998 0.0329 0.0073 3 1.51 0.000081 0.00018 0.4476 

E55CRC-10 1998 0.0305 0.0073 3 1.40 0.000096 0.00018 0.5306 

E55CRC-11 2000 0.0107 0.0073 3 0.49 0.000111 0.00018 0.6101 

E55CRC-11 2000 0.0109 0.0093 2 0.59 0.000092 0.00182 0.0504 

E55CRC-12 1986 0.0087 0.0093 2 0.47 0.001187 0.00182 0.6527 

E55CRC-12 1986 0.0078 0.0093 2 0.42 0.000843 0.00182 0.4638 

E55CRC-13 1978 0.0134 0.0093 2 0.72 0.000455 0.00182 0.2501 

E55CRC-13 1978 0.0132 0.0093 2 0.71 0.000426 0.00182 0.2345 

E55CRC-14 1985 0.0095 0.0093 2 0.51 0.000390 0.00182 0.2144 
Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-14 1985 0.0096 0.0093 2 0.52 0.000376 0.00182 0.2068 

E55CRC-14 1985 0.0096 0.0093 2 0.52 0.000368 0.00182 0.2022 

E55CRC-15 1986 0.0091 0.0093 2 0.49 0.000810 0.00182 0.4455 

E55CRC-15 1986 0.0090 0.0093 2 0.48 0.000728 0.00182 0.4002 

E55CRC-15 1986 0.0090 0.0091 2 0.50 0.000778 0.00045 1.7109 

E55CRC-16 1979 0.0056 0.0091 2 0.31 0.009448 0.00045 20.7851 

E55CRC-16 1979 0.0053 0.0091 2 0.29 0.008619 0.00045 18.9624 

E55CRC-16 1979 0.0058 0.0091 2 0.32 0.008698 0.00045 19.1364 

E55CRC-17 1993 0.0120 0.0109 3 0.37 0.000365 0.00109 0.3349 

E55CRC-17 1993 0.0113 0.0109 3 0.35 0.000429 0.00109 0.3930 

E55CRC-17 1993 0.0115 0.0109 3 0.35 0.000310 0.00109 0.2841 

E55CRC-18 1991 0.0085 0.0109 2 0.39 0.000276 0.00109 0.2529 

E55CRC-18 1991 0.0085 0.0109 3 0.26 0.000263 0.00109 0.2408 

E55CRC-18 1991 0.0088 0.0109 3 0.27 0.000267 0.00109 0.2449 

E55CRC-19 1987 0.0073 0.0109 2 0.34 0.000603 0.00109 0.5529 

E55CRC-19 1987 0.0075 0.0109 2 0.34 0.000633 0.00109 0.5801 

E55CRC-19 1987 0.0075 0.0109 2 0.34 0.000577 0.00109 0.5290 

E55CRC-20 1992 0.0141 0.0091 3 0.52 0.000520 0.00045 1.1443 

E55CRC-20 1992 0.0142 0.0091 3 0.52 0.000534 0.00045 1.1751 

E55CRC-20 1992 0.0135 0.0091 3 0.49 0.000567 0.00045 1.2475 

E55CRC-21 1990 0.0116 0.0109 2 0.53 0.000643 0.00109 0.5891 

E55CRC-21 1990 0.0115 0.0109 3 0.35 0.000623 0.00109 0.5714 

E55CRC-21 1990 0.0118 0.0109 3 0.36 0.000540 0.00109 0.4951 

E55CRC-22 1993 0.0109 0.0091 3 0.40 0.000285 0.00045 0.6262 

E55CRC-22 1993 0.0116 0.0091 3 0.43 0.000268 0.00045 0.5891 

E55CRC-22 1993 0.0114 0.0091 3 0.42 0.000259 0.00045 0.5697 

E55CRC-23 1983 0.0129 0.0109 2 0.59 0.000545 0.00182 0.2997 

E55CRC-23 1983 0.0134 0.0109 2 0.62 0.000577 0.00182 0.3171 

E55CRC-23 1983 0.0134 0.0109 2 0.61 0.000581 0.00182 0.3194 
Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-24 1975 0.0153 0.0182 2 0.42 0.000360 0.00182 0.1977 

E55CRC-24 1975 0.0172 0.0182 2 0.47 0.000324 0.00182 0.1784 

E55CRC-24 1975 0.0162 0.0182 2 0.44 0.000295 0.00182 0.1625 

E55CRC-25 1983 0.0138 0.0109 2 0.63 0.000492 0.00182 0.2704 

E55CRC-25 1983 0.0156 0.0109 2 0.71 0.000464 0.00182 0.2553 

E55CRC-25 1983 0.0156 0.0109 2 0.72 0.000428 0.00182 0.2355 

E55CRC-26 1998 0.0140 0.0073 3 0.64 0.000219 0.00018 1.2024 

E55CRC-27 1999 0.0118 0.0073 3 0.54 0.000148 0.00018 0.8125 

E55CRC-28 1998 0.0155 0.0073 3 0.71 0.000377 0.00018 2.0711 

E55CRC-29 1999 0.0097 0.0073 3 0.44 0.001838 0.00018 10.1100 

E55CRC-30 1998 0.0160 0.0073 3 0.73 0.000148 0.00018 0.8114 

E55CRC-31 1997 0.0178 0.0091 3 0.65 0.000140 0.00018 0.7707 

E55CRC-32 1991 0.0068 0.0091 2 0.37 0.000355 0.00045 0.7809 

E55CRC-33 1984 0.0174 0.0093 2 0.94 0.000471 0.00182 0.2593 

E55CRC-34 2003 0.0040 0.0036 3 0.36 0.000829 0.00018 4.5598 

E55CRC-35 2000 0.0099 0.0073 3 0.45 0.000240 0.00018 1.3176 

E55CRC-36 2001 0.0087 0.0073 3 0.40 0.000211 0.00018 1.1610 

E55CRC-38 2004 0.0049 0.0036 3 0.45 0.000114 0.00018 0.63 

E55CRC-38 2004 0.0045 0.0036 3 0.41 0.000108 0.00018 0.60 

E55CRC-38 2004 0.0049 0.0036 3 0.45 0.000134 0.00018 0.75 

E55CRC-39 2004 0.0047 0.0036 3 0.43 0.000104 0.00018 0.58 

E55CRC-39 2004 0.0044 0.0036 3 0.41 0.000113 0.00018 0.63 

E55CRC-40 2004 0.0074 0.0036 3 0.68 0.000107 0.00018 0.60 

E55CRC-40 2004 0.0082 0.0036 3 0.76 0.000086 0.00018 0.48 

E55CRC-42 2000 0.0075 0.0073 3 0.34 0.000173 0.00018 0.96 

E55CRC-42 2000 0.0077 0.0073 3 0.35 0.000178 0.00018 0.99 

E55CRC-43 1995 0.0138 0.0091 3 0.51 0.000044 0.00018 0.24 

E55CRC-43 1995 0.0123 0.0091 3 0.45 0.000040 0.00018 0.22 

E55CRC-44 1989 0.0090 0.0109 2 0.41 0.000227 0.00109 0.21 
Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-44 1989 0.0088 0.0109 2 0.40 0.000224 0.00109 0.21 

E55CRC-45 1993 0.0060 0.0091 3 0.22 0.000762 0.00045 1.69 

E55CRC-46 1989 0.0104 0.0109 2 0.48 0.000506 0.00109 0.46 

E55CRC-47 1986 0.0056 0.0093 2 0.30 0.000674 0.00182 0.37 

E55CRC-48 1998 0.0162 0.0073 3 0.74 0.000261 0.00018 1.45 

E55CRC-49 1994 0.0080 0.0091 3 0.29 0.000605 0.00018 3.36 

E55CRC-60 1995 0.0098 0.0091 3 0.36 0.000789 0.00018 4.38 

E55CRC-62 1983 0.0090 0.0109 2 0.41 0.001317 0.00182 0.72 

E55CRC-63 2005 0.0074 0.0036 3 0.69 0.000214 0.00018 1.19 

E55CRC-64 1994 0.0154 0.0091 3 0.57 0.000000 0.00018 0.00 

E55CRC-65 1994 0.0132 0.0091 3 0.48 0.000420 0.00018 2.33 

E55CRC-66 1989 0.0109 0.0109 2 0.50 0.000417 0.00109 0.38 

E55CRC-69 1989 0.0083 0.0109 2 0.38 0.000895 0.00109 0.82 

E55CRC-74 1969 0.0135 0.0182 2 0.37 0.001053 0.00182 0.58 

E55CRC-78 1975 0.0249 0.0182 2 0.68 0.001652 0.00182 0.91 
Table 23: T&M Determination Data for the HHDDT Vehicles over the Transient Mod

Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-1 1994 0.0130 0.0091 3 0.48 0.00019 0.00018 1.07 

E55CRC-1 1994 0.0179 0.0091 3 0.66 0.00025 0.00018 1.36 

E55CRC-2 1995 0.0070 0.0091 3 0.26 0.00026 0.00018 1.41 

E55CRC-2 1995 0.0073 0.0091 3 0.27 0.00034 0.00018 1.85 

E55CRC-3 1985 0.0059 0.0093 2 0.32 0.00105 0.00182 0.58 

E55CRC-3 1985 0.0056 0.0093 2 0.30 0.00124 0.00182 0.68 

E55CRC-4 1999 0.0078 0.0073 3 0.36 0.00017 0.00018 0.94 

E55CRC-4 1999 0.0107 0.0073 3 0.49 0.00032 0.00018 1.74 

E55CRC-5 2000 0.0100 0.0073 3 0.46 0.00029 0.00018 1.57 

E55CRC-5 2000 0.0118 0.0073 3 0.54 0.00029 0.00018 1.57 

E55CRC-6 1995 0.0109 0.0091 3 0.40 0.00081 0.00018 4.46 

E55CRC-6 1995 0.0085 0.0091 3 0.31 0.00062 0.00018 3.40 

E55CRC-7 1990 0.0129 0.0109 3 0.39 0.00045 0.00109 0.41 

E55CRC-7 1990 0.0129 0.0109 3 0.40 0.00041 0.00109 0.37 

E55CRC-8 1996 0.0089 0.0091 3 0.33 0.00037 0.00018 2.03 

E55CRC-8 1996 0.0113 0.0091 3 0.41 0.00116 0.00018 6.36 

E55CRC-9 1998 0.0063 0.0073 3 0.29 0.00039 0.00018 2.13 

E55CRC-9 1998 0.0074 0.0073 3 0.34 0.00036 0.00018 2.00 

E55CRC-10 1998 0.0132 0.0073 3 0.60 0.00031 0.00018 1.71 

E55CRC-10 1998 0.0123 0.0073 3 0.56 0.00027 0.00018 1.49 

E55CRC-11 2000 0.0076 0.0073 3 0.35 0.00017 0.00018 0.92 

E55CRC-11 2000 0.0074 0.0093 2 0.40 0.00020 0.00182 0.11 

E55CRC-12 1986 0.0076 0.0093 2 0.41 0.00189 0.00182 1.04 

E55CRC-12 1986 0.0075 0.0093 2 0.41 0.00188 0.00182 1.03 

E55CRC-13 1978 0.0109 0.0093 2 0.59 0.00087 0.00182 0.48 

E55CRC-13 1978 0.0105 0.0093 2 0.57 0.00082 0.00182 0.45 
Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-14 1985 0.0078 0.0093 2 0.42 0.00080 0.00182 0.44 

E55CRC-14 1985 0.0079 0.0093 2 0.43 0.00089 0.00182 0.49 

E55CRC-14 1985 0.0079 0.0093 2 0.42 0.00081 0.00182 0.45 

E55CRC-15 1986 0.0085 0.0093 2 0.46 0.00152 0.00182 0.84 

E55CRC-15 1986 0.0088 0.0093 2 0.47 0.00148 0.00182 0.82 

E55CRC-15 1986 0.0080 0.0091 2 0.44 0.00235 0.00045 5.17 

E55CRC-16 1979 0.0069 0.0091 2 0.38 0.00529 0.00045 11.63 

E55CRC-16 1979 0.0067 0.0091 2 0.37 0.00607 0.00045 13.35 E55CRC-16 1979 0.0067 0.0091 2 0.37 0.00570 0.00045 12.53 E55CRC-17 1993 0.0079 0.0109 3 0.24 0.00075 0.00109 0.69 

E55CRC-17 1993 0.0078 0.0109 3 0.24 0.00084 0.00109 0.77 

E55CRC-17 1993 0.0073 0.0109 3 0.22 0.00080 0.00109 0.73 

E55CRC-18 1991 0.0083 0.0109 2 0.38 0.00066 0.00109 0.60 

E55CRC-18 1991 0.0087 0.0109 3 0.26 0.00106 0.00109 0.97 

E55CRC-18 1991 0.0085 0.0109 3 0.26 0.00106 0.00109 0.97 

E55CRC-19 1987 0.0062 0.0109 2 0.29 0.00256 0.00109 2.34 

E55CRC-19 1987 0.0065 0.0109 2 0.30 0.00210 0.00109 1.93 

E55CRC-19 1987 0.0063 0.0109 2 0.29 0.00271 0.00109 2.48 

E55CRC-20 1992 0.0126 0.0091 3 0.46 0.00004 0.00045 0.09 

E55CRC-20 1992 0.0122 0.0091 3 0.45 0.00056 0.00045 1.23 

E55CRC-20 1992 0.0108 0.0091 3 0.40 0.00057 0.00045 1.26 

E55CRC-21 1990 0.0107 0.0109 2 0.49 0.00101 0.00109 0.92 

E55CRC-21 1990 0.0110 0.0109 3 0.34 0.00106 0.00109 0.97 

E55CRC-21 1990 0.0111 0.0109 3 0.34 0.00102 0.00109 0.93 

E55CRC-22 1993 0.0092 0.0091 3 0.34 0.00099 0.00045 2.17 

E55CRC-22 1993 0.0093 0.0091 3 0.34 0.00090 0.00045 1.97 

E55CRC-22 1993 0.0098 0.0091 3 0.36 0.00099 0.00045 2.17 

E55CRC-23 1983 0.0099 0.0109 2 0.45 0.00120 0.00182 0.66 

E55CRC-23 1983 0.0092 0.0109 2 0.42 0.00125 0.00182 0.69 
Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-23 1983 0.0094 0.0109 2 0.43 0.00122 0.00182 0.67 

E55CRC-24 1975 0.0131 0.0182 2 0.36 0.00078 0.00182 0.43 

E55CRC-24 1975 0.0143 0.0182 2 0.39 0.00169 0.00182 0.93 

E55CRC-24 1975 0.0135 0.0182 2 0.37 0.00071 0.00182 0.39 

E55CRC-25 1983 0.0112 0.0109 2 0.51 0.00087 0.00182 0.48 

E55CRC-25 1983 0.0118 0.0109 2 0.54 0.00081 0.00182 0.45 

E55CRC-25 1983 0.0125 0.0109 2 0.57 0.00071 0.00182 0.39 

E55CRC-26 1998 0.0064 0.0073 3 0.30 0.00029 0.00018 1.60 

E55CRC-27 1999 0.0072 0.0073 3 0.33 0.00044 0.00018 2.39 

E55CRC-28 1998 0.0087 0.0073 3 0.40 0.00222 0.00018 12.23 

E55CRC-29 1999 0.0060 0.0073 3 0.28 0.00220 0.00018 12.12 E55CRC-30 1998 0.0157 0.0073 3 0.72 0.00025 0.00018 1.39 

E55CRC-31 1997 0.0093 0.0091 3 0.34 0.00040 0.00018 2.22 

E55CRC-32 1991 0.0068 0.0091 2 0.37 0.00044 0.00045 0.97 

E55CRC-33 1984 0.0139 0.0093 2 0.75 0.00150 0.00182 0.83 

E55CRC-34 2003 0.0055 0.0036 3 0.51 0.00041 0.00018 2.23 

E55CRC-35 2000 0.0066 0.0073 3 0.30 0.00053 0.00018 2.90 

E55CRC-36 2001 0.0059 0.0073 3 0.27 0.00031 0.00018 1.72 

E55CRC-38 2004 0.0060 0.0036 3 0.55 0.00021 0.00018 1.14 

E55CRC-38 2004 0.0052 0.0036 3 0.49 0.00013 0.00018 0.72 E55CRC-38 2004 0.0059 0.0036 3 0.54 0.00018 0.00018 1.00 E55CRC-39 2004 0.0058 0.0036 3 0.53 0.00014 0.00018 0.78 E55CRC-39 2004 0.0056 0.0036 3 0.52 0.00014 0.00018 0.80 E55CRC-40 2004 0.0063 0.0036 3 0.59 0.00010 0.00018 0.53 E55CRC-40 2004 0.0061 0.0036 3 0.57 0.00010 0.00018 0.54 

E55CRC-42 2000 0.0054 0.0073 3 0.25 0.00038 0.00018 2.09 

E55CRC-42 2000 0.0052 0.0073 3 0.24 0.00035 0.00018 1.94 

E55CRC-43 1995 0.0105 0.0091 3 0.38 0.00038 0.00018 2.09 

E55CRC-43 1995 0.0086 0.0091 3 0.31 0.00011 0.00018 0.62 
Vehicle 

Model Year 

(NOX / CO2) 

Actual 

(NOX/CO2) 

Certification Multiplier 

Actual / (Cert * Multiplier) 

(PM/CO2) 

Actual 

(PM/CO2) 

Certification 

Actual / Certification 

E55CRC-44 1989 0.0081 0.0109 2 0.37 0.00044 0.00109 0.41 

E55CRC-44 1989 0.0081 0.0109 2 0.37 0.00037 0.00109 0.34 

E55CRC-45 1993 0.0058 0.0091 3 0.21 0.00723 0.00045 16.08 

E55CRC-46 1989 0.0080 0.0109 2 0.37 0.00076 0.00109 0.70 

E55CRC-47 1986 0.0062 0.0093 2 0.33 0.00131 0.00182 0.72 

E55CRC-48 1998 0.0113 0.0073 3 0.52 0.00050 0.00018 2.79 

E55CRC-49 1994 0.0069 0.0091 3 0.25 0.00125 0.00018 6.97 

E55CRC-60 1995 0.0098 0.0091 3 0.36 0.00503 0.00018 27.93 

E55CRC-62 1983 0.0082 0.0109 2 0.38 0.00204 0.00182 1.12 

E55CRC-63 2005 0.0053 0.0036 3 0.49 0.00022 0.00018 1.24 

E55CRC-64 1994 0.0090 0.0091 3 0.33 0.00000 0.00018 0.00 

E55CRC-65 1994 0.0105 0.0091 3 0.38 0.00092 0.00018 5.12 

E55CRC-66 1989 0.0084 0.0109 2 0.38 0.00095 0.00109 0.87 

E55CRC-69 1989 0.0087 0.0109 2 0.40 0.00117 0.00109 1.07 

E55CRC-74 1969 0.0113 0.0182 2 0.31 0.00159 0.00182 0.87 

E55CRC-78 1975 0.0190 0.0182 2 0.52 0.00062 0.00182 0.34 
“Before and After” Emissions 

Each vehicle that was identified as a T&M vehicle, repaired and retested, or reflashed and 

retested, is presented below in order of occurrence in the program. 

E55CRC-3: Injection Timing Change, Phase 1. 

E55CRC-3, a single axle full size road tractor with a 1985 Cummins 14 liter engine, 

became a T&M subject fortuitously. It was tested twice, because it was mistakenly 

believed that data from the first set of tests were in error and that retest was necessary, 

and the vehicle owner happened to effect repairs between the two test periods. E55CRC-3 

did not meet the high PM emissions criteria but it was observed during a later data 

analysis that PM was higher than would be expected for a vehicle of its MY and NOx was 

lower. Data from the first round of testing suggested that the engine might be operating at 

NOx levels as low as 3g/bhp-hr (4 g/kw-hr) and the NOx data for the retest corresponded 

to about 4.5g/bhp-hr (6 g/kw-hr) on a certified engine test (FTP), based on NOx/CO2 

ratio. The certification level for that engine was 5.1g/bhp-hr (6.8 g/kw-hr) so 4.5g/bhp-hr 

(6 g/kw-hr) would correspond to certification level less a 10% “safety margin”. Fuel 

specifications in CA. had also changed since 1985 and recent CA fuel is argued to cause 

lower NOx. It was evident from the retest data that the PM, CO and HC were lower in the 

retest than in the original test. Table 24 and Table 25 summarize the data taken from the 

test and retest for laden UDDS. 

Table 26 to Table 29 summarize the data taken from the test and retest for laden 

HHDDT. 

Table 24: E55CRC-3: UDDS (g/mile) 

Run Seq. No. CO NOx 

1

 NOx 

2

 HC PM CO2 mile/gal BTU/mile Miles 

1826-3 14 12.5 12.2 2.7 1.76 2155 4.6 28238 5.52 

1826-4 12.4 12.3 12.6 2.78 1.76 2255 4.41 29450 5.51 

Table 25: E55CRC-3 retest UDDS (g/mile) 

Run Seq. No. CO NOx 

1

 NOx 

2

 HC PM CO2 mile/gal BTU/mile Miles 

1936-2 8.22 17.9 18.8 1.76 1.15 2413 4.13 31421 5.2 

1936-3 8.53 17.1 16.9 1.66 1.57 2408 4.14 31359 5.26 

Table 26: E55CRC-3: 1828-1 Idle, 1828-2 Creep, 1828-3 Transient, 1828-4 Cruise. 

(g/mile, except idle in g/cycle) 

Run Seq. No. CO NOx 

1

 NOx 

2

 HC PM CO2 mile/gal BTU/mile Miles 

1828-1 10.4 8.7 8.8 7.2 1.84 1088 0.02 9052 0.01 

1828-2 26.48 14.42 13.24 12.49 5.10 2740 0.94 36451 0.13 

1828-3 8.58 9.07 8.89 2.98 1.60 965 2.69 12768 2.73 

1828-4 2.30 5.53 5.47 1.12 0.42 549 4.77 7188 23.02 

152 
Table 27: E55CRC-3: 1829-1 Idle, 1829-2 Creep, 1829-3 Transient, 1829-4 Cruise. 

(g/mile, except idle in g/cycle) 

Run Seq. No. CO NOx 

1

 NOx 

2

 HC PM CO2 mile/gal BTU/mile Miles 

1829-1 29.6 1.8 2 2.4 2.37 1167 <0 15780 -0.01 

1829-2 48 25.6 25 23.4 6.05 5896 1.66 78121 0.13 

1829-3 12.6 13.7 14.4 5.6 3.02 1884 5.23 24826 2.78 

1829-4 3.3 7.8 8.1 1.7 0.65 851 11.66 11137 23 

Table 28: E55CRC-3 retest: 1939-1 Idle, 1939-5 Creep, 1939-3 Transient, 1939-4 

Cruise (g/mile, except idle in g/cycle) 

Run Seq. No. CO NOx 

1

 NOx 

2

 HC PM CO2 mile/gal BTU/mile Miles 

1939-1 5.87 9.2 9.2 4.19 0.75 1406 <0 18462 -0.01 

1939-5 20.7 44.3 45.5 10.19 2.53 4878 2.03 63862 0.12 

1939-3 9.47 20.4 20 2.38 1.56 2743 3.63 35731 2.65 

1939-4 2.65 12.4 12.5 0.99 0.45 1579 6.34 20492 22.04 

Table 29: E55CRC-3 retest: 1942-1 Idle, 1942-5 Creep, 1942-3 Transient, 1942-4 

Cruise. (g/mile, except idle in g/cycle) 

Run Seq. No. CO NOx 

1

 NOx 

2

 HC PM CO2 mile/gal BTU/mile Miles 

1942-1 6.8 12.5 12.3 4.28 0.75 1480 <0 80732 0 

1942-5 25.4 31.5 25.7 9.01 3.55 5593 1.77 73153 0.11 

1942-3 11.1 18.6 19 2.95 1.66 3313 3.01 43158 2.63 

1942-4 3.1 10.7 10.8 1.03 0.49 1603 6.24 20812 22.02 

The low NOx in the first round was due to substantially retarded timing on the truck. This 

engine employed a mechanical variable injection timing system, which included an airoperated cylinder that varied the position of the cam followers. It is likely that this unit 

was worn, because during preventive maintenance between the original test and retest, 

the vehicle owner effected repairs to the truck that included a rebuild of this air cylinder 

with new seals. In other words, the timing was corrected between the original testing and 

retesting, resulting in raised NOx, and lower PM, CO and HC, according to the wellknown NOx-PM tradeoff. 

E55CRC-10: Reflash Vehicle in Phase 1 

E55CRC-10, a 1998 MY Sterling tractor with a DDC Series 60 engine, exhibited high 

NOx emissions. The emissions, as tested on the Heavy-Duty UDDS and the HHDDT 

Schedule at 56,000 lbs. (25,402 kg), are shown in Table 22. It was evident that the major 

cause of the elevated emissions was “off-cycle” operation, as shown in Figure 122 above. 

153 
After the vehicle was reflashed, the Transient mode NOx emissions for E55CRC-10 did 

not change, but the UDDS NOx emissions dropped by about 20% as shown in 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

55 

NOx Emissions (g/mile) 

E55CRC-10 

E55CRC-10 reflashed 

UDDS Transient Cruise 

Figure 127 and the reduction on cruise was over 30%. This is to be expected keeping in 

mind the relative amounts of steady operation in each of these test modes and the fact that 

steady operation encourages “off-cycle” behavior. Figure 128 shows the NOx emissions 

versus power for E55CRC-10 after reflash, and this figure may be compared with Figure 

122. The investigators concede that Idle and Creep data were too variable for “before and 

after” comparisons because auxiliary engine loads affect idle and creep modes. 

154 
0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

55 

NOx Emissions (g/mile) 

E55CRC-10 

E55CRC-10 reflashed 

UDDS Transient Cruise 

Figure 127: Transient Mode NOx emissions before and after reflashing E55CRC-10. 

155 
Table 30: E55CRC-10 baseline emissions and “reflash” emissions. T&M runs are 

denoted in bold. NOx

1

 and NOx

2

 show values from two similar analyzers in parallel. 

It should be noted that Idle and Creep Modes often return highly variable emissions 

due to changing auxiliary loads on the vehicle. 

Test ID 

Test 

Run 

ID Driving Schedule CO NOX 

1

 NOX 

2

 HC PM CO2 

(g/mile) (g/mile) (g/mile) (g/mile) (g/mile) (g/mile) 

1963 Before 2 UDDS 8.37 38.68 38.58 0.22 0.53 2190 

1963 Before 3 UDDS 9.16 40.57 40.25 0.22 0.53 2088 

2195 Reflash 5 UDDS 10.02 32.71 32.79 0.27 0.41 2188 

1966 Before 1 Idle 6.45 21.36 22.71 1.49 0.16 1176 

1969 Before 1 Idle 7.65 17.81 17.66 1.15 0.13 923 

2197 Reflash 2 Idle 4.47 27.78 29.73 0.9 0.07 1057 

1966 Before 2 Creep 30.07 54.9 50.52 4.43 1.07 3834 

1969 Before 2 Creep 40.23 60.71 62.35 5.26 1.49 4415 

2197 Reflash 3 Creep 33.31 75.66 75.1 5.4 1.09 4697 

1966 Before 3 Transient 11.77 32.99 33.13 0.46 0.78 2506 

1969 Before 3 Transient 10.91 30.48 31.09 0.49 0.67 2485 

2197 Reflash 4 Transient 9.53 31.71 31.54 0.66 0.59 2666 

1966 Before 4 Cruise 2.78 49.43 49.11 0.13 0.12 1501 

1969 Before 4 Cruise 3.05 46.24 46.42 0.14 0.15 1514 

2197 Reflash 5 Cruise 2.42 33.93 33.58 0.15 0.12 1513 

y 

1.0 

1.2 

= 2E-06x2

 + 0.002x + 0.2032 

R2

 = 0.4803 

Transient 

Cruise 

0.8 

0.6

NOx Emissions (g/s) 

0.4 

0.0 

0.2 

0 50 100 150 200 250 

Axle Horsepower (ahp) 

y = 2E-06x2 + 0.001x + 0.

R2

 = 0.5935 

300 350 

0749 

400 

Figure 128: NOx emissions versus power for E55CRC-10 after reflashing. The mass 

rate of NOx emissions was reduced in many parts of the Cruise mode (compared to 

Figure 122). The highest mass rate emissions were also slightly lower than before the 

reflash. 

156 
E55CRC-16: High PM T&M Vehicle in Phase 1 

E55CRC-16 was a 1979 White tractor with a 3208 Caterpillar engine. It was identified 

visually as a prodigious smoker and returned data as a high emitter. It was chosen as a 

T&M candidate. Emissions data for this vehicle are presented in Table 31. The vehicle 

was naturally aspirated, so the investigators believed that the high PM was due to over 

fueling or substantially retarded timing. It was suggested34 that cam wear also might be 

an issue. The vehicle was sent to a Caterpillar dealership with directions to inspect the 

engine. They found no substantial wear or indication of poor injection timing. The 

dealership determined that the engine had originally been equipped with exhaust gas 

recirculation (EGR) for NOx reduction, but that EGR components had been removed and 

that the system was not functioning. 

The WVU investigators and the program sponsors determined that the fuel pump flow 

should be measured, and corrected if necessary, or the fuel pump should be replaced with 

a rebuilt unit. The dealership determined that they were unable to quantify the flow and 

so the pump was replaced. 

Table 31: E55CRC-16 Emissions before and after T&M procedures. T&M 1 in bold 

represents testing with a new fuel injection pump; T&M 2 in bold italics represents 

testing with a new pump and EGR totally disabled. 

Test ID 

Test Run 

ID 

Driving 

Schedule CO NOX 

1

 NOX 

2

 HC PM CO2 

(g/mile) (g/mile) (g/mile) (g/mile) (g/mile) (g/mile) 

2088 Before 3 UDDS 20.54 14.69 14.83 1.61 10.89 2181 

2088 Before 4 UDDS 20.62 15.29 15.35 2.08 12.99 2316 

2088 Before 5 UDDS 20.44 14.55 14.19 1.52 12.5 2192 

2180 T&M 1 3 UDDS 109.16 13.78 13.87 4.4 24.23 2065 

2182 T&M 2 2 UDDS 60.59 14.79 15.39 1.31 16.31 1821 

2181 Before 1 Idle 9.53 10.23 12.5 1.05 0.54 992 

2183 Before 1 Idle 8.28 6.58 6.24 0.19 0.04 889 

2093 Before 2 Creep 33.1 60.74 59.82 8.59 6.05 3867 

2094 Before 2 Creep 37.92 52.56 50.75 7.25 8.66 3410 

2095 Before 2 Creep 34.52 56.75 56.86 7.46 6.23 3736 

2181 T&M 1 2 Creep 26.89 51.21 53.17 2.64 6.23 3644 

2183 T&M 2 2 Creep 28.67 53.17 54.25 3.29 4.23 3419 

2093 Before 3 Transient 27.13 17.97 17.67 4.08 13.82 2615 

2094 Before 3 Transient 26.97 16.95 16.95 4.08 15.42 2541 

2095 Before 3 Transient 27.22 17.01 16.82 3.74 14.39 2526 

2181 T&M 1 3 Transient 181.23 16.09 15.89 5.48 25.97 2321 

2183 T&M 2 3 Transient 119.05 20.88 21.03 6.7 17.48 2538 

2093 Before 4 Cruise 9.07 10.17 10.25 0.34 17.14 1814 

2094 Before 4 Cruise 8.99 9.5 9.99 0.3 15.37 1784 

2095 Before 4 Cruise 8.99 10.26 10.04 0.33 15.48 1779 

2181 T&M 1 4 Cruise 51.26 10.07 10.23 1.01 9.31 1476 

2183 T&M 2 4 Cruise 19.95 13.2 13.1 1.56 4.6 1504 

157 
The vehicle was retested with the new fuel pump, and data are shown in denoted as T&M 

1. There was virtually no change in the NOx emissions with the new pump on the UDDS, 

the Cruise mode and the Transient mode. PM rose with the new pump for the Transient 

cycle and UDDS, but was lowered for the Cruise mode. 

A final inspection of the vehicle found soot in the intake manifold, which suggested that 

the EGR system was still adding some EGR into the intake. The EGR feed was then 

blocked and this eliminated EGR entirely, and the vehicle was tested again. This was not 

a repair, but a diagnostic move. The elimination of the EGR (with the new fuel injection 

pump) raised the NOx on the Transient and Cruise modes and on the UDDS as shown in 

Table 31 denoted as T&M 2. PM was reduced relative to the PM with the new fuel pump 

prior to disabling the EGR (i.e. PM for T&M 2 was lower than PM for T&M 1), for the 

UDDS, and the Transient and Cruise modes. The Cruise mode reduction was substantial. 

However, it was not clear that the cause of the high PM emissions was completely 

resolved. The final PM levels for E55CRC-16 after both pump replacement and disabling 

of EGR were higher for the UDDS and Transient modes than for the vehicle as received. 

The T&M exercise with E55CRC-16 was therefore not fully successful and emphasized 

the difficulty in attacking an old, potentially worn engine with no single, clear 

malfunction. 

E55CRC-21: T&M Vehicle by Inspection in Phase 1 

E55CRC-21, a 1990 Caterpillar powered tractor, became a T&M vehicle by inspection. 

The air filter was visibly dirty. Table 32 presents the emissions from E55CRC-21. It was 

found using a manometer that the pressure drop across the filter at high air flow (during 

full power acceleration) into the engine was 39 inches of water (9,714 Pa). This exceeded 

the typical recommended intake depression limit of 18 inches of water (4,483 Pa). Intake 

restriction reduces engine air intake flow, increases internal exhaust gas retained in the 

cylinder, lowers the air to fuel ratio, and promotes formation of products of incomplete 

combustion. The filter was replaced with a new filter. The intake depression dropped to 

5.5 inches of water. The vehicle was retested and data are shown in Table 32. PM for the 

vehicle on the UDDS dropped by 27%, while it dropped 18% for the transient mode and 

25% for the Cruise mode. The CO dropped by over 20% for the UDDS and Cruise 

modes, while the Transient mode showed a CO decrease of only 2 percent. The data 

suggest that CO and PM may be reduced by replacing air filters regularly. 

158 
Table 32: E55CRC-21 emissions T&M results in bold. 

Test ID 

Run 

ID Driving Schedule 

CO NOX1 NOX2 HC PM CO2 

(g/mile) (g/mile) (g/mile) (g/mile) (g/mile) (g/mile) 

2156 3 UDDS 19.79 23.79 24.37 0.41 2.89 2389 

2156 4 UDDS 19.16 24.27 24.94 0.49 2.93 2364 

2156 5 UDDS 22.45 23.64 24.22 0.4 3.09 2400 

2168 T&M 3 UDDS 16.19 25.39 25.95 0.43 2.18 2430 

2157 1 CARB - idle3.cyc 9.58 25.49 26.49 1.02 0.27 971 

2158 1 CARB - idle3.cyc 9.81 25.84 26.4 1.85 0.36 1055 

2159 1 CARB - idle3.cyc 13.09 12.5 14.18 1.63 0.38 967 

2169 T&M 1 CARB - idle3.cyc 16.93 24.16 23.62 2.13 0.49 1102 

2157 2 CARB - creep3.cyc 42.37 82.16 82.7 5.76 2.29 4067 

2158 2 CARB - creep3.cyc 47.09 84.99 87.7 6.92 2.68 4220 

2159 2 CARB - creep3.cyc 56.18 87.99 86.1 9.11 3.48 4537 

2169 T&M 2 CARB - creep3.cyc 56.73 79.73 77.26 7.75 3.59 4417 

2157 3 CARB - trans3.cyc 18.62 28.53 28.97 0.96 2.68 2664 

2158 3 CARB - trans3.cyc 20.01 30.03 30.01 1.38 2.89 2733 

2159 3 CARB - trans3.cyc 19.08 29.67 28.69 1.13 2.72 2668 

2169 T&M 3 CARB - trans3.cyc 18.92 28.64 29.33 1.1 2.25 2621 

2157 4 CARB - cruise3.cyc 7.81 18.81 18.26 0.24 1.05 1627 

2158 4 CARB - cruise3.cyc 9.42 18.8 18.56 0.26 1.02 1632 

2159 4 CARB - cruise3.cyc 8.05 19.27 18.94 0.26 0.89 1640 

2169 T&M 4 CARB - cruise3.cyc 6.58 19.76 19.45 0.21 0.74 1618 

2160 1 AC5080 8.36 19.49 19.16 0.31 1.41 1863 

2160 2 AC5080 8.14 19.33 20.87 0.32 1.33 1852 

CRC-26, CRC-28 and CRC-31, Reflash Vehicles in Phase 1.5 

CRC26 was a 1999 Freightliner tractor with a 1998 Caterpillar C-10 Engine. CRC28 was 

a 1999 Freightliner with a 1998 Series 60 Detroit Diesel Engine. CRC31 was a 1998 

Kenworth with a 1997 N14 Cummins engine. E55CRC-26, E55CRC-28 and E55CRC-31 

were tested using the full baseline test program in Phase 1.5. At the end of the baseline 

test program, all three vehicles were reflashed to a “low-NOx” ECU map by their 

respective dealerships, and re-tested. After the reflash, the vehicle was retested using a 

limited set of schedules, as follows. After warming the vehicle and dynamometer, the 

researchers conducted a coastdown, a UDDS at 56,000 lbs., a HHDDT Idle, a HHDDT 

56,000 lbs. Creep Mode, a HHDDT 56,000 lbs. Transient Mode and a HHDDT 56,000 

lbs. Cruise Mode. 

E55CRC-28 was also identified as a high PM emitter, and was tested (i) as received, (ii) 

without repair but with reflash, (iii) with repair and reflash, and (iv) without repair but 

with reflash. E55CRC-31 was a vehicle that required mechanical attention during testing, 

as discussed in a section below. 

Each of the three reflash vehicles is discussed separately below. Figure 129 (as received) 

and Figure 130 (after reflash) show the NOx versus hub power plots for all three reflash 

159 
vehicles on the Cruise Mode. Reduction of NOx due to reflash is evident. E55CRC-31 

still shows a bifurcation in its emissions rate versus power output, but values over 0.8 

g/sec have been eliminated after reflash. 

1.2 

1.0 CRC 26

CRC 28

NOx Emissions (g/s) 

CRC 31

0.8 

0.6 

0.4 

0.2 

0.0 

0 100 200 300 400 500 600 

Hub Power (Hp) 

Figure 129: NOx emissions on Cruise mode (56,000 lbs.) for three vehicles before 

reflash. NOx emissions and hub power were time-aligned before plotting. 

1.2 

1.0 CRC 26 R 

CRC 28 R 

NOx Emissions (g/s) 

CRC 31 R 0.8 

0.6 

0.4 

0.2 

0.0 

0 100 200 300 400 500 600 

Hub Power (Hp) 

Figure 130: NOx emissions on the three reflash vehicles were reduced in Cruise 

mode after reflash. Test weight was 56,000 lbs. 

160 
As-received and reflash data for NOx for E55CRC-26 are presented in Figure 131. As 

might be expected, transient operation was not affected by the reflash, and the NOx data 

for the UDDS, Creep mode and Transient mode did not change appreciably due to 

reflash. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

NOx Emissions (g/mile) 

UDDS 

Creep 

Trans. 

Cruise 

UDDS 15.99 16.10 

Creep 45.27 46.84 

Trans. 16.73 16.53 

Cruise 24.19 16.77 

E55CRC-26 E55CRC-26R 

Figure 131: As-received and retest after reflash NOx data for E55CRC-26 (56,000 

lbs.). 

0.0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

NOx Emissions (g/mile) 

UDDS 

Creep 

Trans. 

Cruise 

UDDS 0.81 0.59 

Creep 0.62 0.72 

Trans. 0.76 0.79 

Cruise 0.38 0.21 

E55CRC-26 E55CRC-26R 

Figure 132: As-received and retest after reflash PM data for E55CRC-26 (56,000 

lbs.). 

161 
The Cruise Mode, however, exhibited a reduction in NOx from 24.19 to 16.77 g/mile due 

to the reflash. PM data for the Creep Mode, and Transient mode were not changed 

appreciably by the reflash, but the PM for the UDDS was 27% lower and the PM for the 

Cruise mode dropped from 0.38 to 0.21 g/mile after the reflash. One might expect PM 

values to rise slightly after a reflash as part of the NOx -PM tradeoff, but TEOM data 

(0.37 g/mile as-received, 0.20 g/mile after reflash) were consulted and found to support 

the substantial reduction in PM filter mass on the Cruise mode after reflash. 

E55CRC-28, selected as a reflash vehicle, was also identified as a high PM emitter. The 

researchers suggested that the cause might be a failed manifold air pressure (MAP) 

sensor. The MAP sensor is used in the engine control strategy to limit fueling in 

sympathy with rising turbocharger boost during transients that demand rise in torque. 

Without fueling limitation, the combustion becomes insufficiently lean and elemental 

carbon is produced in rich zones during combustion. High CO is also produced by failure 

to limit fueling during transients, and E55CRC-28 was also observed to have high CO 

emissions. Valley Detroit Diesel, a dealership in Fontana, CA, confirmed that the MAP 

sensor had failed, and were able to provide a new sensor. These sensors are readily 

changed. 

PM was the species of interest for the repair. Figure 133 and Figure 134 show the PM 

levels produced by E55CRC-28 on the UDDS and HHDDT (four modes) at 56,000 lbs. 

test weight with and without reflash and with and without MAP sensor replacement 

(repair). 

0.0 

1.0 

2.0 

3.0 

4.0 

5.0 

6.0 

NOx Emissions (g/mile) 

UDDS 

Cruise 

HHDDT_S 

UDDS 5.24 0.81 1.11 2.69 

Cruise 0.65 0.19 0.37 0.50 

HHDDT_S 1.13 0.32 0.49 0.75 

E55CRC-28 E55CRC-28 Repair 

without reflash 

E55CRC-28 Repair 

& reflash 

E55CRC-28 

Reflash without 

repair 

Figure 133: PM emission for E55CRC-28 for the UDDS, Cruise and HHDDT_S 

Modes. 

162 
0.0 

2.0 

4.0 

6.0 

8.0 

10.0 

12.0 

14.0 

PM Emissions (g/mile) 

Transient 

Creep 

Transient 6.10 1.80 1.64 3.01 

Creep 12.17 1.86 1.71 1.39 

E55CRC-28 E55CRC-28 Repair 

without reflash 

E55CRC-28 Repair 

& reflash 

E55CRC-28 Reflash 

without repair 

Figure 134: PM emissions for the Transient and Creep Modes for E55CRC-28. 

In all cases, repair lowered PM substantially, whether with or without reflash of the ECU. 

However, PM was also lowered in general for the reflash without repair. In the case of 

the Creep Mode, the PM from reflash without repair was below even the values for PM 

with repair. However, PM is known to be variable on the Creep Mode. It is possible to 

curb PM production even if the MAP sensor fails by adding a time-based fueling 

limitation to the ECU strategy. However, the authors have no direct information as to 

whether the reflash code may have contained this added strategy. 

The reflash would be expected to influence NOx more than other species. Figure 135 and 

Figure 136 show the NOx levels before and after reflash. The repair without the reflash 

raised NOx values by about 30% for the UDDS and the four HHDDT modes. The reflash 

did little to abate NOx for the Transient and Creep Modes, but offered modest reductions 

for the Cruise and HHDDT_S Modes and the UDDS for the repaired condition. NOx on 

the UDDS was actually found to rise slightly on the UDDS for the case without repair. 

163 
45.0 

40.0 

35.0 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

UDDS 

Cruise 

HHDDT_s 

NOx Emissions (g/mile) 

E55CRC-28 

UDDS 25.73 

Cruise 26.63 

HHDDT_s 32.45 

E55CRC-28 Repair 

without reflash 

33.57 

33.57 

42.46 

E55CRC-28 Repair 

& reflash 

29.43 

26.36 

27.88 

E55CRC-28 

Reflash without 

repair 

29.22 

18.95 

21.33 

Figure 135: NOx emissions for E55CRC-28 at 56,000 lbs. on the UDDS and the 

Cruise and HHDDT_S Modes. 

0.0 

10.0 

20.0 

30.0 

40.0 

50.0 

60.0 

70.0 

80.0 

90.0 

100.0 

NOx Emissions (g/mile) 

Transient 

Creep 

Transient 23.79 33.11 31.89 24.31 

Creep 54.34 76.36 93.63 81.28 

E55CRC-28 E55CRC-28 Repair 

without reflash 

E55CRC-28 Repair 

& reflash 

E55CRC-28 

Reflash without 

repair 

Figure 136: NOx emissions for E55CRC-28 at 56,000 lbs. on the Transient and 

Creep Modes. 

164 
E55CRC-31 was subjected to as-received testing and testing after reflash. The vehicle 

suffered from a clutch failure, an exhaust leak, and a fuel injector failure during testing. 

The initial testing of vehicle E55CRC-31 was conducted on 7/2/03 during the time of the 

speciation sampling. HHDDT and UDDS tests were performed at 56,000 lbs. and an 

HHDDT at 66,000 lbs. The vehicle was re-procured on 7/15/03 for the HHDDT 30,000 

lbs. test to complete the as-received testing. 

The vehicle was then sent to a local dealership to be “reflashed” for a low NOx 

calibration. On 7/16/03, the vehicle was retested with the reflash. One HHDDT at 56,000 

lbs. was completed but the required UDDS was not performed. 

The vehicle was brought back on 7/28/03 to complete the reflash testing. While 

conducting the retest with the low NOx reflash of vehicle E55CRC-31, a significant 

exhaust leak developed. The vehicle was removed from the test bed to repair the exhaust 

leak and testing continued with other vehicles. When vehicle E55CRC-31 was procured 

again, a problem with the clutch prevented testing. WVU staff adjusted the clutch but this 

did not solve the problem. A technician from the rental company was called to service the 

vehicle. Both the clutch-brake and the clutch were found to need replacement. While 

testing the vehicle after changing the clutch, an engine mis-fire was detected that was not 

present during prior testing. The technician determined the problem to be a faulty 

injector. The fuel injector was replaced. Testing was completed. Table 33 shows the 

sequences of repairs and retests. These repairs were not treated as T & M repairs. 

Table 33: Sequence of testing for E55CRC-31 

Date Tests performed Seq. No. Action 

7/2/03 56,000 HHDDT 

56,000 UDDS 

66,000 HHDDT 

2532 

2534 

2535 

Tests reported 

7/15/03 30,000 HHDDT 2573 Tests reported 

7/16/03 56,000 HHDDT reflash 

did not do the 56,000 UDDS 

2577/78 Tests not reported 

7/28/03 56,000 HHDDT reflash (Trans3, Cruise3) to verify 

data from 7/16/03 

56,000 UDDS reflash (significant exhaust leak 

developed) 

Found problems with the clutch, clutch brake, and 

fuel injector 

2625 

2626 

Tests not reported 

Truck repaired 

8/19/03 56,000 HHDDT reflash 

56,000 UDDS reflash 

2685 

2684 

Tests reported 

As-received and reflash emissions are shown in Figure 137 and Figure 138. The reflash 

reduced NOx emissions (in g/mile) for the UDDS and the Creep, Transient and Cruise 

modes of the HHDDT. PM emissions (in g/mile) rose slightly on the UDDS, and dropped 

from 1.24 g/mile to 0.76 g/mile on the Transient Mode, but were otherwise changed little. 

However, it was found that CO2 emissions were also reduced, (as shown in the short 

reports in Appendix K) which is not expected, so that g/gallon values are not aligned with 

the distance specific values. 

165 
0.0 

10.0 

20.0 

30.0 

40.0 

50.0 

60.0 

70.0 

80.0 

NOx Emissions (g/mile) 

UDDS 

Creep 

Trans. 

Cruise 

UDDS 21.91 16.79 

Creep 72.16 64.34 

Trans. 28.50 20.31 

Cruise 28.11 24.36 

E55CRC-31 E55CRC-31R 

Figure 137: As-received and reflash emissions for NOx emissions for E55CRC-31 

tested at 56,000 lbs. 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

PM Emissions (g/mile) 

UDDS 

Creep 

Trans. 

Cruise 

UDDS 0.50 0.57 

Creep 1.21 1.16 

Trans. 1.24 0.76 

Cruise 0.22 0.20 

E55CRC-31 E55CRC-31R 

Figure 138: As-received and reflash emissions for PM emissions for E55CRC-31 

166 
CRC-45 T&M High PM Vehicle in Phase 2 

The Phase 2 E-55/59 program test plan included a provision for repair and retest of one 

vehicle that was identified during the T&M inspection or determined otherwise to have 

abnormally high emissions. Vehicle E55CRC-45 was noted visually to be a prodigious 

smoker. It was not a high emitter on the Cruise mode but was a high emitter (on only one 

test run) on the Transient mode. This vehicle emitted PM at an impressively high level at 

low engine load. On the Creep mode, the PM mass (67.8 g/mile) exceeded the NOx mass 

substantially, and PM exceeded NOx also on the Transient mode. The high PM mass was 

accompanied by exceptionally high HC emissions. In some cases, the HC emissions were 

of the order of one tenth of the fuel burned to form CO2, and it was realized that raw fuel 

was most likely being admitted to the exhaust stream. 

The sponsors were notified of the high emissions and they elected to authorize repair and 

retest. A repair was effected: it was determined at the dealership that the No. 1 injector 

timing was out of specification, and the injector was replaced. The vehicle was retested as 

E55CRC-45R. PM remained high after the repair. Both PM and NOx were reduced on the 

Creep mode, but NOx and PM mass were still similar to one another (38.2 and 37.5 

g/mile respectively). On Transient mode PM was virtually unchanged. PM rose from 1.1 

g/mile on the Cruise mode before repair to 4.5 g/mile on the Cruise mode after repair, and 

a similar increase was seen on the HHDDT_S. Clearly the emissions from the vehicle had 

changed, but the cause of the high PM at low load had not been addressed. 

The vehicle was returned to the dealer for additional diagnosis and repair, and a 

reconditioned turbocharger was fitted. Data collected after this second repair were 

recorded under the vehicle designation E55CRC-45RR. The emissions changed, but the 

high PM was not cured. Once again, on Creep and Transient modes, the PM mass was 

similar to the NOx mass. 

Table 34 shows the emissions from E55CRC-45 as received, after the first repair, and 

after the second repair. It is evident that the PM emissions were associated with high HC 

emissions and that the fault was not diagnosed. The WVU investigators suspect that a 

leak from an injector into the cylinder might have been the cause, but no further repairs 

were authorized by the sponsors. 

167 
Table 34: E55CRC-45 as received, after first repair (R), and after second repair (RR)

WVU Ref Num Test ID 

Test Run ID Cycle CO g/mile CO2 g/mile NOx g/mile NOx 2 g/mile HC g/m

E55CRC-45 2967 2 TEST_D 3.47 2029 11.98 12.36 15.76 E55CRC-45 R 2985 1 TEST_D 5.42 2230 11.11 11.20 31.70 

E55CRC-45 RR 20008 1 TEST_D 9.70 2164 11.78 12.04 29.24 

E55CRC-45 2968 3 TRANS3 4.99 2369 13.68 13.63 29.46 

E55CRC-45 R 2986 3 TRANS3 7.14 2502 12.72 12.70 47.03 

E55CRC-45 RR 20009 3 TRANS3 15.56 2513 13.61 13.42 40.96 E55CRC-45 2968 2 CREEP34 32.95 3806 44.97 44.14 222.73 

E55CRC-45 R 2986 2 CREEP34 27.66 4061 38.38 37.95 158.52 

E55CRC-45 RR 20009 2 CREEP34 47.56 3857 40.80 38.14 134.90 

E55CRC-45 2968 4 CRUISE3 1.53 1468 8.81 8.77 5.43 E55CRC-45 R 2986 7 CRUISE3 2.69 1447 7.13 7.33 17.40 

E55CRC-45 RR 20009 6 CRUISE3 5.39 1372 10.33 10.33 14.54 

E55CRC-45 2968 5 HHDDT_S 1.18 1612 9.62 9.46 3.09 

E55CRC-45 R 2986 5 HHDDT_S 2.69 1611 8.30 8.41 19.78 E55CRC-45 RR 20009 7 HHDDT_S 4.39 1580 10.54 10.42 17.09 
E55CRC57: MHDT Temperature Sensor Failure 

There were no formal criteria for identifying high MHDT emissions. Vehicle CRC57, a 

MHDDT powered by a Caterpillar engine, showed unusually high unladen NOx 

emissions. This vehicles apparently had an issue with a temperature sensor that indicated 

an overheated engine to the ECU. The ECU would then command a limp home mode 

resulting in the vehicle’s inability to follow the test target speed (See Figure 139). The 

clutch actuated cooling fan would only kick in after the engine actually was warm. At 

that point the driver could return the vehicle speed to one consistent with the target trace. 

Conversation with Robert Graze, of Caterpillar, confirmed that the WVU diagnosis of a 

temperature sensor misrepresenting the temperature to the ECU was reasonable. 

70.0 

60.0 

50.0 

Actual (mph) 

Target (mph) 

40.0 

30.0 

20.0 

10.0 

0.0 

0 500 1000 1500 2000 2500 

Time (sec) 

Figure 139: shows the inability of E55CRC-57 to meet the target trace. 

T&M and Reflash Discussion 

Identification of vehicles for T&M by inspection proved successful insofar as it targeted 

E55-21, with a dirty air filter. Also, the excessive smoking of E55CRC-16 and E55CRC45 provided visual indications of T&M vehicles. However, inspections are difficult to 

perform, and some forms of tampering with sensors may be difficult to identify. In this 

way, visual inspection is not foolproof, but will detect some emissions-related problems. 

The method of identifying high PM emitters also appeared to be sound, and used the best 

approach that could be employed for rapid processing of field data. Moreover, the 

identification of high PM emitters using data from two different HHDDT Schedule 

Modes (Transient and Cruise) allowed the researchers to infer the cause of the smoking. Speed (mph) 

169 
High PM emissions on the Transient Mode, without high emissions on the Cruise Mode, 

might indicate poor puff control. 

The criterion for identifying high NOx emitters was based on a multiple of the 

certification NOx to CO2 ratio. NOx tracks CO2 closely for a vehicle with a timing map 

that keeps location of peak in-cylinder pressure at the same crank angle over a broad 

operating range. In this way, the NOx to CO2 ratio should be largely cycle independent, 

and should rise with advanced timing and fall with retarded timing. Unfortunately this 

approach is confused by the timing strategy that causes “off-cycle” NOx emissions in 

many electronic engines. Off-cycle strategies may be based on two maps, one with 

advanced timing (high NOx), and one with retarded timing (low NOx), and these maps 

may be invoked during different sections of a cycle. Off-cycle strategies cannot be 

regarded as a T&M target because the engine is behaving in the way that it was originally 

sold, and any high NOx emissions arising during off-cycle use are neither due to 

tampering nor due to malmaintenance. 

Being cognizant of the “off-cycle” phenomenon, the researchers set generous T&M 

margins to detect high NOx emitters. The intent was not to snare off-cycle trucks, but to 

detect only extreme (uncharacteristically high) NOx emitters. In execution of this 

strategy, only one high NOx emitter was detected, and this was determined through 

further study to be rooted in an off-cycle issue. An important point was that the emissions 

for this vehicle, E55CRC-10, were extreme for the Cruise Mode: it is known that steady 

state cruising tends to elicit off-cycle behavior in many cases. The investigators also 

admit that E55CRC-10 was found to be high because the criterion was developed with 5 

g/bhp-hr (6.7 g/kw-hr) NOx engines in mind, while E55CRC-10 was a 4 g/bhp-hr (5.4 

g/kw-hr) engine. The criterion should perhaps have been a NOx to CO2 ratio that was 

fixed in value (say 0.03 by mass) rather than “three times the certification ratio”. 

However, E55CRC-10 would still have just been high on Cruise mode with a 0.03 

criterion. It would have had “expected” emissions levels after reflashing if a 0.03 

criterion were used. Otherwise, more sophisticated strategies, using plots such as those 

shown in Figure 122, could be used to distinguish high NOx T&M trucks from “offcycle” behavior. The E55CRC-10 findings, in part, led to the reflash research in Phase 

1.5 of the program, where reflash NOx reductions were verified. 

As part of an inventory program in southern California, trucks that were identified as 

high emitters were repaired and retested for emissions. A 1990 Caterpillar-powered 

tractor was identified as having a dirty air filter, and air filter replacement did reduce CO 

and PM emissions. A 1979 Caterpillar-powered truck was identified as a prodigious 

smoker, but the cause of the high emissions was not satisfactorily identified. A 1998 

Detroit Diesel-powered tractor was identified as having high NOx emissions, but they 

were attributed to “off-cycle” timing strategies rather than T&M issues. The vehicle was 

“reflashed” with a more retarded timing strategy and lower NOx emissions were seen 

under cruise conditions. In the case of a 1985 Cummins-powered tractor, repairs to a 

failed variable mechanical injection timing system raised NOx to an expected level and 

reduced other regulated emissions. For a 1993 Cummins-powered truck, the cause of 

excessive PM production was not cured, despite two rounds of repair: it was evident that 

170 
the high PM was associated with exceptionally high HC emissions. A MHDDT 

malfunctioned during testing, and was unable to follow the trace due to a false high 

temperature warning. This was not an emissions fault, but did affect distance-specific 

emissions by not allowing the vehicle to follow the cycle closely. It is concluded that 

trucks that are poorly maintained or have failures are contributing additional emissions to 

the inventory, but that diagnosis and repair is not necessarily straightforward. 

171 
ACKNOWLEDGEMENTS 

The WVU researchers are grateful to the sponsors listed below, for support of this 

program. 

• Coordinating Research Council, Inc. 

• California Air Resources Board 

• U.S. Environmental Protection Agency 

• U.S. Department of Energy Office of FreedomCAR & Vehicle Technologies 

through the National Renewable Energy Laboratory 

• South Coast Air Quality Management District 

• Engine Manufacturers Association 

The dedication of the WVU field research team is gratefully acknowledged. 

Ralphs Grocery was kind to provide a location for the WVU laboratory during part of this 

research program. 

The contributions of Thomas R. Long, Jr., Sairam Thiagarajan, Shuhong (Susan) Xu, 

David McKain and Kuntal Vora in preparing and editing sections of this report are 

acknowledged. 

172 
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176