40 CFR Part 1066 

Vehicle-Testing 

Procedures 

DRAFT Working 

Document

(LD Tier III NPRM changes denoted by “track changes” – the latest set of changes, Round 

7, are in gray) 

2/15/13 
Part 1066—Vehicle-Testing Procedures 

Subpart A—Applicability and General Provisions 

1066.1 Applicability. 

1066.2 Submitting information to EPA under this part. 

1066.5 Overview of this part 1066 and its relationship to the standard-setting part. 

1066.10 Other procedures. 

1066.15 Overview of test procedures. 

1066.20 Units of measure and overview of calculations. 

1066.25 Recordkeeping. 

Subpart B—Equipment, Measurement Instruments, Fuel, and Analytical Gas 

Specifications 

1066.101 Overview. 

1066.110 Equipment specifications.

1066.120 Measurement instruments.

1065.122 Data updating, recording, and control for measurement instruments.

1066.130 Measurement instrument calibrations and verifications.

1066.137 Linearity verification.

1066.140 Diluted exhaust flow calibration.

1066.145 Engine fluids, test fuels, analytical gases, and other calibration standards.

1066.150 Analyzer interference and quench verification limit.

 

Subpart C—Dynamometer Specifications 

1066.201 Dynamometer overview. 

1066.210 Dynamometers. 

1066.215 Summary of verification and calibration procedures for chassis dynamometers. 

1066.220 Linearity verification for chassis dynamometer systems. 

1066.225 Roll runout and diameter verification procedure. 

1066.230 Time verification procedure. 

1066.235 Speed verification procedure. 

1066.240 Torque transducer calibration. 

1066.245 Response time verification. 

1066.250 Base inertia verification. 

1066.255 Parasitic loss verification. 

1066.260 Parasitic friction compensation evaluation. 

1066.265 Acceleration and deceleration verification. 

1066.270 Unloaded coastdown verification.

1066.280 Dynamometer readiness verification.

1066.290 Driver’s aid. 

 Subpart D—Coastdown 

Deleted: 1066.133 Summary of required 

calibrations and verifications.¶

Deleted: (CVS) 

Deleted: 0

Deleted: 4

Deleted: verification and 

Deleted: 8
1066.301 Overview of coastdown procedures.

1066.305 Coastdown procedures for motor vehicles at or below 14,000 pounds GVWR.

1066.310 Coastdown procedures for vehicles above 14,000 pounds GVWR.

1066.320 Dynamometer road-load setting.

 Subpart E—Preparing Vehicles and Running an Exhaust Emission Test 

1066.401 Overview. 

1066.407 Vehicle preparation and preconditioning. 

1066.410 Dynamometer test procedure. 

1066.420 Vehicle operation. 

1066.425 Test preparation. 

1066.430 Performing emission tests.

Subpart F—Hybrids and Electric Vehicles

1066.501 Overview. 

 Subpart G—Calculations 

1066.601 Overview. 

1066.610 Mass-based and molar-based exhaust emission calculations. 

1066.620 Dilution air background correction.

1066.630 NOx intake-air humidity correction.

1066.640 Removed water correction.

1066.650 Flow meter calibration calculations.

1066.652 PDP, SSV, and CFV flow rate calculations.

1066.665 NMOG determination.

1066.695 Data requirements.

Subpart H—Cold-Temperature Test Procedures

1066.701 Applicability and general provisions.

Subpart I—Exhaust Emission Test Procedures for Motor Vehicles

1066.801 Applicability and general provisions.

1066.810 Road load power, test weight, and inertia weight class determination.

1066.812 Test sequence; general requirements.

1066.814 Vehicle preparation.

1066.820 Exhaust emission test procedures for FTP emissions.

1066.822 FTP exhaust emission calculations.

1066.830 Supplemental Federal Test Procedures; overview.

1066.831 Exhaust emission test procedures for agressive driving.

1066.832 Exhaust emission test procedure for SC03 emissions.

1066.835 AC17 Air conditioning efficiency test procedure.

Deleted: with GVWR 

Deleted: lbs

Deleted: heavy-duty 

Deleted: with GVWR 

Deleted: lbs

Deleted: Preparation 

Deleted: Pre-test verification procedures and pretest data collection

Deleted: Engine starting and restarting

Deleted: emission 

Deleted: and temperature 

Deleted: s

Deleted: SSV

Deleted: CF

Deleted: PDP

Deleted: Under 14,000 GVWR

Deleted: 1066.803 EPA dynamometer driving 

schedules.¶

Deleted: 1066.816 SFTP vehicle preconditioning.¶

Deleted: 1066.818 Records required.¶

Deleted: Calculations; 

Deleted: s

Deleted: US06 emissions

Deleted: 1066.833 Test facility requirements for 

the 

Deleted: A

Deleted: air conditioning 

Deleted: environmental test facility ambient 

requirements

Deleted: test element.¶

Deleted: 1066.834 Approval of alternative air 

conditioning test simulations and descriptions of 

AC1 and AC2.¶
1066.839 Highway fuel economy test procedure.

1066.840 Fuel storage system leak test procedure.

Subpart J—[Reserved]

 Subpart K—Definitions and Other Reference Material 

1066.1001 Definitions. 

1066.1005 Symbols, abbreviations, acronyms, and units of measure. 

1066.1010 Reference materials. 

Deleted: 1066.836 Spot check correlation 

procedures for vehicles tested using a simulation of 

the environmental test cell for air conditioning 

emission testing.¶

Deleted: 1066.837 Supplemental Federal Test 

Procedure calculations.¶

1066.838 Air conditioning idle test procedure.¶

Deleted: Method for calculating emissions due to 

air conditioning leakage.¶

1066.843 

Deleted: H

Deleted: 701 

Deleted: 705 

Deleted: 710 
Subpart A—Applicability and General Provisions 

§1066.1 Applicability. 

(a) This part describes the procedures that apply to testing we require for the following vehicles: 

(1) Model year 2014 and later heavy-duty highway vehicles we regulate under 40 CFR part 1037 

that are not subject to chassis testing for exhaust emissions under 40 CFR part 86. 

(2) Model year 2022 and later highway vehicles that are subject to chassis testing for exhaust 

emissions under 40 CFR part 86. See 40 CFR part 86 for provisions describing how to 

implement this part 1066.

(b) The procedures of this part may apply to other types of vehicles, as described in this part and 

in the standard-setting part. 

(c) The term “you” means anyone performing testing under this part other than EPA. 

(1) This part is addressed primarily to manufacturers of vehicles, but it applies equally to anyone 

who does testing under this part for such manufacturers. 

(2) This part applies to any manufacturer or supplier of test equipment, instruments, supplies, or 

any other goods or services related to the procedures, requirements, recommendations, or options 

in this part. 

(d) Paragraph (a) of this section identifies the parts of the CFR that define emission standards 

and other requirements for particular types of vehicles. In this part, we refer to each of these 

other parts generically as the “standard-setting part.” For example, 40 CFR part 1037 is the 

standard-setting part for heavy-duty highway vehicles and parts 86 and 600 are the standardsetting parts for light-duty vehicles. For vehicles subject to 40 CFR part 86, subpart S, 

references to the standard-setting part include subpart I of this part.

(e) Unless we specify otherwise, the terms “procedures” and “test procedures” in this part 

include all aspects of vehicle testing, including the equipment specifications, calibrations, 

calculations, and other protocols and procedural specifications needed to measure emissions. 

(f) For additional information regarding these test procedures, visit our Web site at www.epa.gov, 

and in particular http://www.epa.gov/nvfel/testing/regulations.htm. 

§1066.2 Submitting information to EPA under this part. 

(a) You are responsible for statements and information in your applications for certification, 

requests for approved procedures, selective enforcement audits, laboratory audits, productionline test reports, or any other statements you make to us related to this part 1066. If you provide 

statements or information to someone for submission to EPA, you are responsible for these 

statements and information as if you had submitted them to EPA yourself. 

(b) In the standard-setting part and in 40 CFR 1068.101, we describe your obligation to report 

truthful and complete information and the consequences of failing to meet this obligation. See 

also 18 U.S.C. 1001 and 42 U.S.C. 7413(c)(2). This obligation applies whether you submit this 

information directly to EPA or through someone else. 

(c) We may void any certificates or approvals associated with a submission of information if we 

find that you intentionally submitted false, incomplete, or misleading information. For example, 

if we find that you intentionally submitted incomplete information to mislead EPA when 

requesting approval to use alternate test procedures, we may void the certificates for all engine 

families certified based on emission data collected using the alternate procedures. This would 

also apply if you ignore data from incomplete tests or from repeat tests with higher emission 

results. 

Deleted: the standard setting part 

Deleted: guidelines for implementation of 

Deleted: ''standard

Deleted: '' 

Deleted: field test reports, 
(d) We may require an authorized representative of your company to approve and sign the 

submission, and to certify that all the information submitted is accurate and complete. This 

includes everyone who submits information, including manufacturers and others. 

(e) See 40 CFR 1068.10 for provisions related to confidential information. Note however that 

under 40 CFR 2.301, emission data are generally not eligible for confidential treatment. 

(f) Nothing in this part should be interpreted to limit our ability under Clean Air Act section 208 

(42 U.S.C. 7542) to verify that vehicles conform to the regulations. 

§1066.5 Overview of this part 1066 and its relationship to the standard-setting part. 

(a) This part specifies procedures that can apply generally to testing various categories of 

vehicles. See the standard-setting part for directions in applying specific provisions in this part 

for a particular type of vehicle. Before using this part’s procedures, read the standard-setting 

part to answer at least the following questions: 

(1) What drive schedules must I use for testing? 

(2) Should I warm up the test vehicle before measuring emissions, or do I need to measure coldstart emissions during a warm-up segment of the duty cycle? 

(3) Which exhaust constituents do I need to measure? Measure all exhaust constituents that are 

subject to emission standards, any other exhaust constituents needed for calculating emission 

rates, and any additional exhaust constituents as specified in the standard-setting part. See 40 

CFR 1065.5 regarding requests to omit measurement of N2O and CH4 for vehicles, not subject to 

N2O or CH4 emission standards. 

(4) Do any unique specifications apply for test fuels? 

(5) What maintenance steps may I take before or between tests on an emission-data vehicle? 

(6) Do any unique requirements apply to stabilizing emission levels on a new vehicle? 

(7) Do any unique requirements apply to test limits, such as ambient temperatures or pressures? 

(8) [Reserved]

(9) Are there any emission standards specified at particular operating conditions or ambient 

conditions? 

(10) Do any unique requirements apply for durability testing? 

(b) The testing specifications in the standard-setting part may differ from the specifications in 

this part. In cases where it is not possible to comply with both the standard-setting part and this 

part, you must comply with the specifications in the standard-setting part. The standard-setting 

part may also allow you to deviate from the procedures of this part for other reasons. 

(c) The following table shows how this part divides testing specifications into subparts: 

Deleted: is 

Deleted: '

Deleted: We may approve your 

Deleted: a

Deleted: provided it is 

Deleted: an 

Deleted: 

Deleted: and we determine that other information 

is available to give us a reasonable basis for 

estimating or approximating the vehicle’s emission 

rates

Deleted: Is field testing required or allowed, and 

are there different emission standards or procedures 

that apply to field testing? 
Table 1 of §1066.5—Description of Part 1066 subparts. 

This subpart Describes these specifications or procedures 

Subpart A Applicability and general provisions. 

Subpart B Equipment for testing. 

Subpart C Dynamometer specifications. 

Subpart D Coastdowns for testing. 

Subpart E How to prepare your vehicle and run an emission test. 

Subpart F How to test hybrid vehicles. 

Subpart G Test procedure calculations. 

Subpart H Cold temperature testing. 

Subpart I Exhaust emission test procedures for motor vehicles.

Subpart J Reserved.

Subpart K Definitions and reference material.

§1066.10 Other procedures. 

(a) Your testing. The procedures in this part apply for all testing you do to show compliance 

with emission standards, with certain exceptions listed in this section. In some other sections in 

this part, we allow you to use other procedures (such as less precise or less accurate procedures) 

if they do not affect your ability to show that your vehicles comply with the applicable emission 

standards. This generally requires emission levels to be far enough below the applicable 

emission standards so that any errors caused by greater imprecision or inaccuracy do not affect 

your ability to state unconditionally that the engines meet all applicable emission standards. 

(b) Our testing. These procedures generally apply for testing that we do to determine if your 

vehicles comply with applicable emission standards. We may perform other testing as allowed 

by the Act. 

(c) Exceptions. We may allow or require you to use procedures other than those specified in this 

part as described in 40 CFR 1065.10(c). All the test procedures noted as exceptions to the 

specified procedures are considered generically as "other procedures." Note that the terms 

"special procedures" and "alternate procedures" have specific meanings; "special procedures" are 

those allowed by 40 CFR 1065.10(c)(2) and "alternate procedures" are those allowed by 40 CFR 

1065.10(c)(7). If we require you to request approval to use other procedures under this 

paragraph (c), you may not use them until we approve your request. 

§1066.15 Overview of test procedures. 

This section outlines the procedures to test vehicles that are subject to emission standards. 

(a) In the standard-setting part, we set emission standards in g/mile (or g/km), for the following 

constituents: 

(1) Total oxides of nitrogen, NOx. 

(2) Hydrocarbons, HC, which may be expressed in the following ways: 

(i) Total hydrocarbons, THC. 

(ii) Nonmethane hydrocarbons, NMHC, which results from subtracting methane (CH4) from 

THC. 

(iii) Total hydrocarbon-equivalent, THCE, which results from adjusting THC mathematically to 

be equivalent on a carbon-mass basis. 

(iv) Nonmethane hydrocarbon-equivalent, NMHCE, which results from adjusting NMHC 

mathematically to be equivalent on a carbon-mass basis.

Deleted: Definitions and reference material

Deleted: for laboratory testing

Deleted: , field testing, or both,

Deleted: (

Deleted: )
(v) Nonmethane organic gases, NMOG, which are calculated either from fully or partially 

speciated measurement of hydrocarbons including oxygenates, or by adjusting measured NMHC 

values based on fuel oxygenate properties.

(3) Particulate mass, PM. 

(4) Carbon monoxide, CO.

(5) Carbon dioxide, CO2.

(6) Methane, CH4.

(7) Nitrous oxide, N2O.

(8) Formaldehyde, CH2O.

(b) Note that some vehicles may not be subject to standards for all the emission constituents 

identified in paragraph (a) of this section. 

(c) The provisions of this part apply for chassis dynamometer testing where vehicle speed is

controlled to follow a prescribed duty cycle while simulating vehicle driving through the 

dynamometer’s road-load settings. We generally set emission standards over test intervals 

and/or drive schedules, as follows: 

(1) Vehicle operation. Testing involves measuring emissions and miles travelled while operating 

the vehicle on a chassis dynamometer. Refer to the definitions of “duty cycle” and “test 

interval” in §1066.1001. Note that a single drive schedule may have multiple test intervals and 

require weighting of results from multiple test intervals to calculate a composite distance-based 

emission value to compare to the standard. 

(2) Constituent determination. Determine the total mass of each constituent over a test interval 

by selecting from the following methods: 

(i) Continuous sampling. In continuous sampling, measure the constituent’s concentration 

continuously from raw or dilute exhaust. Multiply this concentration by the continuous (raw or 

dilute) flow rate at the emission sampling location to determine the constituent’s flow rate. Sum 

the constituent’s flow rate continuously over the test interval. This sum is the total mass of the 

emitted constituent. 

(ii) Batch sampling. In batch sampling, continuously extract and store a sample of raw or dilute 

exhaust for later measurement. Extract a sample proportional to the raw or dilute exhaust flow 

rate, as applicable. You may extract and store a proportional sample of exhaust in an appropriate 

container, such as a bag, and then measure HC, CO, and NOx concentrations in the container 

after the test interval. You may deposit PM from proportionally extracted exhaust onto an 

appropriate substrate, such as a filter. In this case, divide the PM by the amount of filtered 

exhaust to calculate the PM concentration. Multiply batch sampled concentrations by the total 

(raw or dilute) flow from which it was extracted during the test interval. This product is the total 

mass of the emitted constituent. 

(iii) Combined sampling. You may use continuous and batch sampling simultaneously during a 

test interval, as follows: 

(A) You may use continuous sampling for some constituents and batch sampling for others. 

(B) You may use continuous and batch sampling for a single constituent, with one being a 

redundant measurement, subject to the provisions of 40 CFR 1065.201. 

(d) Refer to the standard-setting part for calculations to determine g/mile emission rates. 

(e) You must use good engineering judgment for all aspects of testing under this part. While the 

regulation highlights several specific cases where good engineering judgment is especially 

relevant, the requirement to use good engineering judgment is not limited to those provisions 

where we specifically re-state this requirement. 

Deleted: and road load are

Deleted: may 

Deleted: in a laboratory

Deleted: -type

Deleted: environment

Deleted: or in the field

Deleted: . 

Deleted: The standard-setting part specifies how 

test intervals are defined for field testing. 

Deleted: 701

Deleted: phase

Deleted: phase

Deleted: T

Deleted: . You must use good engineering 

judgment for all aspects of testing under this part, 

not only for
§1066.20 Units of measure and overview of calculations. 

(a) System of units. The procedures in this part follow both conventional English Units and the 

International System of Units (SI), as detailed in NIST Special Publication 811, which we 

incorporate by reference in §1066.1010. Except where specified, equations work with any 

system of units. Where the equations depend on the use of specific units, these units are 

identified.

(b) Units conversion. Use good engineering judgment to convert units between measurement 

systems as needed. For example, if you measure vehicle speed as kilometers per hour and we 

specify a precision requirement in terms of miles per hour, convert your measured kilometer per 

hour value to miles per hour before comparing it to our specification. The following conventions 

are used throughout this document and should be used to convert units as applicable: 

(1) 1 hp = 33,000 ft·lbf/min = 550 ft·lbf/s = 0.7457 kW. 

(2) 1 lbf = 32.174 ft·lbm/s2 = 4.4482 N.

(3) 1 inch = 25.4 mm.

(4) 1 mile = 1609.344 m.

(5) For ideal gases, 1 μmol/mol = 1 ppm.

(6) For ideal gases, 10 mmol/mol = 1 %.

(7) Unless specified otherwise, use absolute temperature and absolute pressure. 

(c) Rounding. The rounding provisions of 40 CFR 1065.20 apply for calculations in this part. 

This generally specifies that you round final values but not intermediate values. Use good 

engineering judgment to record the appropriate number of significant digits for all measurements. 

(d) Interpretation of ranges. Interpret a range as a tolerance unless we explicitly identify it as an 

accuracy, repeatability, linearity, or noise specification. See 40 CFR 1065.1001 for the 

definition of tolerance. In this part, we specify two types of ranges: 

(1) Whenever we specify a range by a single value and corresponding limit values above and 

below that value (such as X ±Y), target the associated control point to that single value (X). 

Examples of this type of range include “±10 % of maximum pressure”, or “(30 ±10) kPa”. In 

these examples, you would target the maximum pressure or 30 kPa, respectively.

(2) Whenever we specify a range by the interval between two values, you may target any 

associated control point to any value within that range. An example of this type of range is “(40 

to 50) kPa”. 

(e) Scaling of specifications with respect to an applicable standard. Because this part 1066 

applies to a wide range of vehicles and emission standards, some of the specifications in this part 

are scaled with respect to a vehicle’s applicable standard or weight. This ensures that the 

specification will be adequate to determine compliance, but not overly burdensome by requiring 

unnecessarily high-precision equipment. Many of these specifications are given with respect to a 

“flow-weighted mean” that is expected at the standard or during testing. Flow-weighted mean is 

the mean of a quantity after it is weighted proportional to a corresponding flow rate. For 

example, if a gas concentration is measured continuously from the raw exhaust of an engine, its 

flow-weighted mean concentration is the sum of the products of each recorded concentration 

times its respective exhaust flow rate, divided by the sum of the recorded flow rates. As another 

example, the bag concentration from a CVS system is the same as the flow-weighted mean 

concentration, because the CVS system itself flow-weights the bag concentration. 

§1066.25 Recordkeeping. 

Deleted: s

Deleted: 710

Deleted: mph

Deleted: m/s

Deleted: mph

Deleted: m/s

Deleted: 5

Deleted: , unless otherwise specified in the 

standard-setting part states otherwise

Deleted: any 

Deleted: Refer to 40 CFR 1065.602 for 

information needed to estimate and calculate flowweighted means.
The procedures in this part include various requirements to record data or other information. 

Refer to the standard-setting part and §1066.695 regarding recordkeeping requirements. You 

must promptly send us organized, written records in English if we ask for them. We may review 

them at any time. 

Deleted: If the standard-setting part does not 

specify recordkeeping requirements, store these 

records in any format and on any media. 

Deleted: and k

Deleted: Keep routine emission test records (such 

as test cell temperature and humidity readings) for a 

period of one year after issuance of all certificates of 

conformity to which they relate. Keep all records, 

other than routine emission test records, required to 

be produced by the manufacturer 

Deleted: them 

Deleted: readily available for 

Deleted: one 

Deleted: eight years after 

Deleted: you send an associated application for

Deleted: we issue your 

Deleted: certification

Deleted: certificate

Deleted: , or one eight years after you generate the 

data if they do not support an application for 

certification

Deleted: . 
Subpart B—Equipment, Measurement Instruments, Fuel, and Analytical Gas 

Specifications 

§1066.101 Overview. 

(a) This subpart addresses equipment related to emission testing, as well as test fuels and 

analytical gases. This section addresses emission sampling and analytical equipment, test fuels, 

and analytical gases. 

(b) The provisions of 40 CFR part 1065 specify engine-based procedures for measuring 

emissions. Except as specified otherwise in this part, the provisions of 40 CFR part 1065 apply 

for testing required by this part as follows: 

(1) The provisions of 40 CFR part 1065, subpart B, describe equipment specifications for 

exhaust dilution and sampling systems; these specifications apply for testing under this part as 

described in §1066.110. 

(2) The provisions of 40 CFR part 1065, subpart C, describe specifications for measurement 

instrument; these specifications apply for testing under this part as described in §1066.120. 

(3) The provisions of 40 CFR part 1065, subpart D, describe specifications for measurement 

instrument calibrations and verifications; these specifications apply for testing under this part as 

described in §1066.130.

(4) The provisions of 40 CFR part 1065, subpart H, describe specifications for fuels, engine 

fluids, and analytical gases; these specifications apply for testing under this part as described in 

§1066.145.

(5) The provisions of 40 CFR part 1065, subpart I, describe specifications for testing with 

oxygenated fuels; these specifications apply for NMOG determinations as described in

§1066.665.

(c) The provisions of this subpart are intended to specify systems that can very accurately and 

precisely measure emissions from motor vehicles such as light-duty vehicles. To the extent that 

this level of accuracy and/or precision is not necessary for testing highway motorcycles or 

nonroad vehicles, we may waive or modify the specifications and requirements of this part for 

testing these other vehicles, consistent with good engineering judgment. For example, it may be 

appropriate to allow the use of a hydrokinetic dynamometer that is not able to meet all the 

performance specifications described in this subpart.

§1066.110 Equipment specifications.

(a) This section specifies equipment related to emission testing, other than measurement 

instruments. This equipment includes two broad categories—dynamometers (described further 

in subpart C of this part) and emission-sampling hardware. Other related sections in this subpart 

identify measurement instruments (§1066.120), describe how to evaluate the performance of 

these instruments (§§1066.130 and 1066.137), describe how to calibrate a CVS (§1066.140),

specify engine fluids and analytical gases (§1066.145), and specify requirements for analyzer 

interference and quench verification (§1066.150). 

(b) The following equipment specifications apply for testing under this part:

(1) Sampling system connections. Connect a vehicle’s exhaust system to any dilution stage as 

follows:

(i) Minimize laboratory exhaust tubing lengths. You may use a total length of laboratory tubing

up to 4 m. However, you may use a total length of laboratory tubing up to 10 m if you insulate 

Deleted: 1065.140 through 1065.195

Deleted: specify 

Deleted: ,

Deleted: s

Deleted: and D, specify 

Deleted: s

Deleted: and their calibrations

Deleted: specify 

Deleted: 3

Deleted: specify 

Deleted: 0

Deleted: specify requirements 

Deleted: as described 

Deleted: ¶

(4) The provisions of 40 CFR part 1065, subpart J, 

describe how to measure emissions from vehicles 

operating outside of a laboratory, except that 

provisions related to measuring engine work do not 

apply.

Deleted: W

Deleted: as 

Deleted: 0

Deleted: of N2O analyzers 

Deleted: 45

Deleted: ,
or heat the tubing to minimize the temperature difference between the exhaust gas and the tubing 

wall over the course of the emission test. The laboratory exhaust tubing starts at the end of the 

vehicle’s tailpipe. The laboratory exhaust tubing ends at the first sample point or the point of

first dilution. You may use flexible laboratory exhaust tubing at any location in the laboratory 

exhaust system. For multiple-tailpipe configurations where the tailpipes combine into a single 

flow path for emission sampling, the start of the laboratory exhaust tubing may be taken at the 

last joint where the exhaust flow first becomes a single, combined flow.

(ii) You may insulate or heat any laboratory exhaust tubing. 

(iii) Use laboratory exhaust tubing materials that are smooth-walled and not chemically reactive 

with exhaust constituents. For measurements involving PM, tubing materials must also be 

electrically conductive. Stainless steel is an acceptable material for any measurements. You 

may use short sections of nonconductive flexible tubing to connect a PM sampling system to the 

vehicle’s tailpipe; use good engineering judgment to limit the amount of nonconductive surface 

area exposed to the vehicle’s exhaust.

(iv) We recommend that you use laboratory exhaust tubing that has either a wall thickness of less 

than 2 mm or is air gap-insulated to minimize temperature differences between the wall and the 

exhaust.

(v) Seal your system to the extent necessary to ensure that any remaining leaks do not affect your 

ability to demonstrate compliance with the applicable standards.

(vi) Electrically ground the entire exhaust system, with the exception of nonconductive flexible 

tubing, as allowed under paragraph (b)(1)(iii) of this section.

(vii) For vehicles with multiple tailpipes, route the exhaust into a single flow. To ensure mixing 

of the multiple exhaust streams before emission sampling, you may configure the exhaust system 

with turbulence generators, such as orifice plates or fins, to achieve good mixing. We 

recommend a minimum Reynolds number, Re#, of 4000 for the combined exhaust stream, where 

Re# is based on the inside diameter of the combined flow at the first sampling point. Re# is 

defined in 40 CFR 1065.640.

(2) Provisions from 40 CFR part 1065. Use equipment specifications in sections 40 CFR 

1065.140 through 40 CFR 1065.190, except as follows:

(i) For PM background measurement, the following provisions apply instead of the analogous 

provisions in 40 CFR 1065.140(b):

(A) You need not measure PM background for every test. You may apply PM background 

correction using a moving-average background value as long as your background PM sample

media (e.g., filters) were all made by the same manufacturer from the same material . Use good 

engineering judgment to determine how many background samples make up the moving average

and how frequently to update those values. For example, you might take one background sample 

per week and average that sample into previous background values, maintaining five 

observations for each calculated average value. Background sampling time should be 

representative of the test interval duration to which the background correction is applied.

(B) You may sample background PM from the dilution tunnel at any time before or after an 

emission test using the same sample train used during the emission test. For this background 

sampling, the dilution tunnel blower must be turned on, the vehicle must be disconnected from 

the exhaust transfer tube, and the exhaust transfer tube must be capped.

(C) Using good engineering judgment, the duration of your background sample does not need to 

be the same as the test cycle in which you are applying the background correction.

Deleted: of 

Deleted: universal

Deleted: Minimize leaks as needed

Deleted: on

Deleted: ’

Deleted: the requirements 

Deleted: with the following exceptions

Deleted: phase

Deleted: to be 
(D) Your background correction may not exceed 5 μg or 5 % of the net PM mass expected at the 

standard, whichever is greater.

(ii) The provisions of 40 CFR 1065.140(d)(2)(iv) do not apply.

(iii) For PM samples, configure dilution systems using the following limits:

(A) Control the dilution air temperature as described in 40 CFR 1065.140(e)(1), except that the 

temperature may set to (15 to 52) °C. Use good engineering judgment to control PM sample

temperature as required under 40 CFR 1065.140(e)(4).

(B) Apply the provisions of this paragraph (b)(2)(iii)(B) instead of 40 CFR 1065.140(e)(2). Add 

dilution air to the raw exhaust such that the overall dilution factor of diluted exhaust to raw 

exhaust, as determined in Eq. 1066.620-2 or 1066.620-3, is within the range of (7:1 to 20:1). 

Compliance with this dilution factor range may be determined for an individual test interval or as 

a time weighted average over the entire duty cycle as determined in Eq. 1066.620-4. The 

maximum dilution factor limit of 20:1 does not apply for plug-in hybrid electric vehicles 

(PHEVs) and hybrid electric vehicles (HEVs), since the dilution factor is infinite when the 

engine is off; however we strongly recommend that you stay under the maximum dilution factor 

limit when the engine is running. For partial-flow sampling systems, determine dilution factor 

using Eq. 1066.620-3. When determining dilution factor for PM samples utilizing secondary 

dilution air, multiply the dilution factor by the dilution ratio of secondary dilution air to primary 

diluted exhaust.

(iv) In addition to the allowances in 40 CFR 1065.140(c)(6) to address aqueous condensation in 

the CVS, you may also heat the dilution air as described in paragraph (b)(2)(iii)(A) of this 

section.

(v) If you choose to dilute the exhaust by using a remote mix tee, you may use the following 

provisions, using good engineering judgment, provided they do not affect your ability to 

demonstrate compliance with the standard:

(A) You may use accordion-style or smooth-walled flexible tubing in the dilution tunnel 

upstream of flow or gaseous emission measurement locations.

(B) You may use smooth-walled electrically conductive flexible tubing in the dilution tunnel 

upstream of where PM emission measurements are made.

(C) Materials for inside surfaces are limited to 300 series stainless steel and polymer-based 

materials.

(D) Use good engineering judgment to ensure that the materials you choose do not cause or 

contribute to unrepresentative loss of PM to your sample.

(vi) Paragraph (b)(1)(vi) of this section applies instead of 40 CFR 1065.145(b).

(c) The following table summarizes the requirements of paragraph (b)(2) of this section:

Deleted: diluent

Deleted: diluent

Deleted: equation

Deleted: 10

Deleted: for each test 

Deleted: phase

Deleted: interval

Deleted: F

Deleted: s have instances of operation where the 

fuelled engine is off, although 

Deleted: equation

Deleted: to prevent or limit aqueous condensation

Deleted: CVS construction. 

Deleted: which dilutes the exhaust at the tailpipe, 

Deleted: show that you comply

Deleted: where 

Deleted: s are made

Deleted: used are limited to 

Deleted: of 

Deleted: , or cause 

Deleted: the provisions in 
Table 1 of §1066.110–Summary of equipment specifications from 40 CFR part 1065, subpart B,

that apply for chassis testing

40 CFR part 1065 

references Applicability for chassis testing under this part

40 CFR 1065.140

Use all except:

40 CFR 1065.140(b) applies as described in this 

section.

Use 40 CFR 1065.140(c)(6), with the additional 

allowance described in this section.

Do not use 40 CFR 1065.140(d)(2)(iv). 

Use 40 CFR 1065.140(e)(1) as described in this

section. 

Do not use 40 CFR 1065.140(e)(2).

40 CFR 1065.145 Use all except 40 CFR 1065.145(b).

40 CFR 1065.150 

through 1065.190 Use all.

§1066.120 Measurement instruments.

The measurement instrument requirements in 40 CFR part 1065, subpart C, apply with the 

following exceptions:

(a) The provisions of §1066.122 apply instead of 40 CFR 1065.202.

(b) The provisions of 40 CFR 1065.210 and 1065.295 do not apply.

Deleted: 2

Deleted: as 
§1066.122 Data updating, recording, and control for measurement instruments.

This section specifies criteria that your test system must meet for updating and recording data. It 

also specifies criteria for controlling the systems related to driver demand, the dynamometer, 

sampling equipment, and measurement instruments.

(a)(1) This paragraph (a)(1) applies where we specify a minimum command and control 

frequency that is greater than the minimum recording frequency, such as for sample flow rates 

from a CVS that does not have a heat exchanger. For these measurements, the rate at which you 

read and interpret the signal must be at least as frequent as the minimum command and control 

frequency. Values may be recorded at the same frequency. They may also be recorded as means 

of the values, provided the frequency of the mean values meets the minimum recording 

frequency. All values read must be either recorded or used to calculate the mean values. For 

example, if your system reads and controls the sample flow rate at 10 Hz, you may record these 

values at 10 Hz, record them at 5 Hz by averaging pairs of consecutive points together, or record 

them at 1 Hz by averaging five consecutive points together. 

(2) For all other measured values covered by this section, you may record the values 

instantaneously or as mean values, consistent with good engineering judgment. 

(3) You may not use rolling averages of measured values where a given measured value is 

included in more than one recorded mean value. 

(b) Use data acquisition and control systems that can command, control, and record at the 

following minimum frequencies:

Table 1 of §1066.122–Data recording and control minimum frequencies

Applicable 

Section Measured Values

Minimum 

Command and 

Control 

Frequency

Minimum 

Recording 

Frequencya

§1066.310

§1066.320 Vehicle speed — 10 Hz

§1066.430 Continuous concentrations of raw or dilute 

analyzers — 1 Hz

§1066.430

§1066.501 Power analyzerb — 1 Hz

§1066.430 Bag concentrations of raw or dilute analyzers — 1 mean value 

per test interval

40 CFR 1065.545

§1066.430

Diluted exhaust flow rate from a CVS with a 

heat exchanger upstream of the flow 

measurement

— 1 Hz

40 CFR 1065.545

§1066.430

Diluted exhaust flow rate from a CVS without 

a heat exchanger upstream of the flow 

measurement

N/A 1 Hz means

40 CFR 1065.545

§1066.430

Dilution air flow if actively controlled (for 

example, a partial flow PM sampler) 5 Hz 1 Hz means

40 CFR 1065.545

§1066.430

Sample flow from a CVS that has a heat 

exchanger 1 Hz 1 Hz

40 CFR 1065.545

§1066.430

Sample flow from a CVS that does not have a 

heat exchanger 5 Hz 1 Hz means

§1066.425 Ambient temperature — 1 Hz

§1066.425 Ambient humidity — 1 Hz

§1066.425 Heated sample system temperatures, including 

PM filter face — 1 Hz

a

1 Hz means are data reported from the instrument at a higher frequency, but recorded as a series of mean 

Deleted: Your 

Deleted: be able to 

Deleted: e

Deleted: must 

Deleted: a

Deleted: phase

Deleted: 5 Hz
values at a rate of 1 Hz.

b

For power analyzers’ sampling frequency, follow SAE J1711 (incorporated by reference in §1066.1010). Deleted: a

Deleted: for sampling frequency
§1066.130 Measurement instrument calibrations and verifications.

The measurement instrument calibration and verification requirements in 40 CFR 1065, subpart 

D, apply with the following exceptions:

(a) The calibration and verification provisions of 40 CFR 1065.303 do not apply for engine speed, 

torque, fuel rate, or intake air flow. Section 1066.133 specifies additional calibration and 

verification provisions that apply specifically for chassis testing.

(b) The linearity verification provisions of 40 CFR 1065.307 do not apply for engine speed, 

torque, fuel rate, or intake air flow. Section 1066.137 specifies additional linearity verification 

provisions that apply specifically for chassis testing.

(c) The provisions of §1066.220 apply instead 40 CFR 1065.310.

(d) The provisions of 40 CFR 1065.320, 1065.325, and 1065.395 do not apply.

(e) If you are measuring flow volumetrically, the provisions of §1066.140 apply instead of 40 

CFR 1065.340.

(f) The provisions of §1066.150 apply instead 40 CFR 1065.350(c), 1065.355(c), 1065.370(c),

and 1065.375(c).

(g) Table 1 of this section summarizes the required and recommended calibrations and 

verifications that are unique to testing under this part and indicates when these have to be 

performed. Perform other required or recommended calibration and verifications as described in 

40 CFR 1065.303, with the exceptions noted in this section. Table 1 follows:

Table 1 of §1066.133–Summary of required calibration and verifications.

Type of calibration or verification Minimum frequencya

40 CFR 1065.303: Flow rates This calibration does not apply for testing under this part; see §1066.133 for 

alternative provisions.

40 CFR 1065.307: Linearity verification

The linearity calibrations from 40 CFR part 1065 do not apply under this part for 

engine speed, torque, fuel rate, or intake air flow; the linearity verification described 

in §1066.137 applies for the following measurements:

Dynamometer Speed: See §1066.220.

Dynamometer Torque: See §1066.220.

40 CFR 1065.310: Torque This calibration does not apply for testing under this part; see §1066.220.

40 CFR 1065.320: Fuel flow This calibration does not apply for testing under this part.

40 CFR 1065.325: Intake flow This calibration does not apply for testing under this part.

40 CFR 1065.340: CVS calibration This calibration does not apply for CVS flow meters calibrated volumetrically as 

described in §1066.140.

40 CFR 1065.345: Vacuum leak

Required upon initial installation of the sampling system; recommended within 35

days before the start of an emissions test and after maintenance such as pre-filter 

changes.

40 CFR 1065.350(c), 1065.355(c), 

1065.370(c), and 1065.375(c) These provisions do not apply for testing under this part; see §1066.150.

40 CFR 1065.395: Inertial PM balance 

and weighing These verifications do not apply for testing under this part.

a

Perform calibrations and verifications more frequently if needed to conform to the measurement system manufacturer’s

instructions and good engineering judgment.

§1066.137 Linearity verification.

This section describes requirements for linearity verification that are unique to testing under this 

part. (Note: see the definition of “linearity” in 40 CFR 1065.1001, where we explain that 

linearity means the degree to which measured values agree with respective reference values and 

that the term “linearity” is not used to refer to the shape of a measurement instrument's 

unprocessed response curve.) Perform other required or recommended calibration and 

verifications as described in 40 CFR 1065.307, with the exceptions noted in this section. 

Deleted: apply for flow rates (except intake air and 

fuel flow), gas division, concentration, temperature, 

and mass. The provisions of 40 CFR 1065.303 

Deleted: electrical power, 

Deleted: apply for flow rates (except intake air and 

fuel flow), gas division, concentration, temperature, 

and mass. The provisions of 40 CFR 1065.307 

Deleted: electrical power, 

Deleted: d

Deleted: replace references in

Deleted: to mean molar flow rate of the reference 

flow meter, ref n , with the mean volumetric flow 

rate of the reference flow meter, Vref



Deleted: e

Deleted: 4

Deleted: ¶

(f) The provisions of 40 CFR 1065.320, 1065.325, 

and 1065.395 do not apply. 

Deleted: ¶

§1066.133 Summary of calibrations and 

verifications.¶

This section

Deleted: §1066.137: Linearity verification

Deleted: Current: Upon initial installation, within 

370 days before testing and after major maintenance.¶

Voltage: Upon initial installation, within 370 days 

before testing and after major maintenance.¶

Deleted: Fuel flow rate, and Intake air flow: 

Linearity verification is not required for testing 

under this subpart.

Deleted: ..

Deleted: , according 
(a) For testing under this subpart, linearity verification under 40 CFR part 1065 is not required 

for speed, torque, fuel flow rate, or intake air flow.

(b) For gas analyzer linearity, you may use one of the following options:

(1) Use instrument manufacturer recommendations and good engineering judgment to select at 

least ten reference values, yrefi, that cover the range of values that you expect during testing (to 

prevent extrapolation beyond the verified range during emission testing). We recommend 

selecting zero as one of your reference values. For each range calibrated, if the deviation from a 

least-squares best-fit straight line is 2 % or less of the value at each data point, concentration 

values may be calculated by use of a single calibration factor for that range. If the deviation 

exceeds 2 % at any point, use the best-fit nonlinear equation that represents the data to within 

2 % of each test point to determine concentration. If you use a gas divider to blend calibration 

gases, verify that the calibration curve produced names a calibration gas within 2 % of its 

certified concentration. Perform this verification between 15 and 50 % of the full scale analyzer 

range.

(2) Use the linearity requirements of 40 CFR 1065.307, except for CO2 measurements used for 

determining fuel economy and GHG emissions for motor vehicles at or below 14,000 pounds. If 

you choose this linearity option, you must drift check and drift correct your emission data 

according to 40 CFR 1065.672.

(c) Perform linearity verifications for the following temperature measurements instead of those 

specified at 40 CFR 1065.307(e)(7):

(1) Test cell ambient air.

(2) Dilution air for PM sampling, including CVS, double-dilution, and partial-flow systems.

(3) PM sample.

(4) Chiller sample, for gaseous sampling systems that use thermal chillers to dry samples and 

that use chiller temperature to calculate dewpoint at the chiller outlet. For testing, if you choose 

to use the high alarm temperature setpoint for the chiller temperature as a constant value in 

determining the amount of water removed from the emission sample, you may verify the 

accuracy of the high alarm temperature setpoint using good engineering judgment without 

following the linearity verification for chiller temperature. We recommend that you input a 

simulated reference temperature signal below the alarm setpoint, increase this signal until the 

high alarm trips, and verify that the alarm setpoint value is no less than 2 °C below the reference 

value at the trip point.

(5) CVS inlet temperature.

(d) Perform linearity verifications for the following pressure measurements instead of those 

specified at 40 CFR 1065.307(e)(8):

(1) Exhaust back pressure.

(2) Barometric pressure.

(3) CVS inlet gage pressure or absolute pressure transducer.

(4) Sample dryer, for gaseous sampling systems that use either osmotic-membrane or thermal 

chillers to dry samples. For your testing, if you choose to use a low alarm pressure setpoint for 

the sample dryer pressure as a constant value in determining the amount of water removed from 

the emission sample, you may verify the accuracy of the low alarm pressure setpoint using good 

engineering judgment without following the linearity verification for sample dryer pressure. We 

recommend that you input a reference pressure signal above the alarm setpoint, decrease this 

signal until the low alarm trips, and verify that the alarm setpoint value is no more than 4 kPa 

above the reference value at the trip point. 

Deleted: a

Deleted: would 

Deleted: these values 

Deleted: percent

Deleted: percent

Deleted: -

Deleted: which 

Deleted: percent

Deleted: shall be used 

Deleted: part 

Deleted: with a GVWR 

Deleted: lbs

Deleted: , if applicable

Deleted: the 

Deleted: of the chiller

Deleted: high 

Deleted: optionally use good engineering 

judgment to 

Deleted: instead of 

Deleted: on the

Deleted: removed 

Deleted: use good engineering judgment to 

Deleted: instead of 

Deleted: on the
(e) When following procedures or practices that we incorporate by reference in §1066.1010, you 

must meet the linearity requirements given by the procedure or practice for any analytical 

instruments not covered under 40 CFR 1065.307, such as GC-FID or HPLC.

§1066.140 Diluted exhaust flow calibration.

(a) Overview. This section describes how to calibrate flow meters for diluted exhaust constantvolume sampling (CVS) systems. You may follow the molar flow calibration procedures in 40 

CFR 1065.340 instead of the procedures in this section.

(b) Scope and frequency. Perform this calibration while the flow meter is installed in its 

permanent position, except as allowed in paragraph (c) of this section. Perform this calibration 

after you change any part of the flow configuration upstream or downstream of the flow meter 

that may affect the flow-meter calibration. Perform this calibration upon initial CVS installation 

and whenever corrective action does not resolve a failure to meet the diluted exhaust flow 

verification (i.e., propane check) in 40 CFR 1065.341.

(c) Ex-situ CFV and SSV calibration. You may remove a CFV or SSV from its permanent 

position for calibration as long as it meets the requirements in 40 CFR 1065.340(c).

(d) Reference flow meter. Calibrate a CVS flow meter using a reference flow meter such as a 

subsonic venturi flow meter, a long-radius ASME/NIST flow nozzle, a smooth approach orifice, 

a laminar flow element, a set of critical flow venturis, or an ultrasonic flow meter. Use a 

reference flow meter that reports quantities that are NIST-traceable within ±1 % uncertainty. 

Use this reference flow meter’s response to flow as the reference value for CVS flow-meter 

calibration.

(e) Configuration. Calibrate the system with any upstream screens or other restrictions that will 

be used during testing and that could affect the flow ahead of the reference flow meter. You 

may not use any upstream screen or other restriction that could affect the flow ahead of the 

reference flow meter, unless the flow meter has been calibrated with such a restriction.

(f) PDP calibration. Calibrate a positive-displacement pump (PDP) to determine a flow-versusPDP speed equation that accounts for flow leakage across sealing surfaces in the PDP as a 

function of PDP inlet pressure. Determine unique equation coefficients for each speed at which 

you operate the PDP. Calibrate a PDP flow meter as follows:

(1) Connect the system as shown in Figure 1 of this section.

(2) Leaks between the calibration flow meter and the PDP must be less than 0.3 % of the total 

flow at the lowest calibrated flow point; for example, at the highest restriction and lowest PDPspeed point. 

(3) While the PDP operates, maintain a constant temperature at the PDP inlet within ±2 % of the 

mean absolute inlet temperature, Tin .

(4) Set the PDP speed to the first speed point at which you intend to calibrate.

(5) Set the variable restrictor to its wide-open position.

(6) Operate the PDP for at least 3 min to stabilize the system. Continue operating the PDP and 

record the mean values of at least 30 seconds of sampled data of each of the following quantities:

(i) The mean flow rate of the reference flow meter, Qref

 . This may include several 

measurements of different quantities, such as reference meter pressures and temperatures, for 

calculatingQref

 .

(ii) The mean temperature at the PDP inlet, Tin .

Deleted: d

Deleted: that contain 

Deleted: (for example,

Deleted: ), you must meet the linearity 

requirements given by the procedure or practice

Deleted: (CVS) 

Deleted: In lieu of these procedures, y

Deleted: -based 

Deleted: 40 CFR part

Deleted: §

Deleted: 40 CFR part

Deleted: Do
(iii) The mean static absolute pressure at the PDP inlet, in p .

(iv) The mean static absolute pressure at the PDP outlet, out p .

(v) The mean PDP speed, nPDP f .

(7) Incrementally close the restrictor valve to decrease the absolute pressure at the inlet to the 

PDP, in p .

(8) Repeat the steps in paragraphs (e)(6) and (7) of this section to record data at a minimum of 

six restrictor positions ranging from the wide-open restrictor position to the minimum expected

pressure at the PDP inlet.

(9) Calibrate the PDP by using the collected data and the equations in §1066.650(a).

(10) Repeat the steps in paragraphs (e)(6) through (9) of this section for each speed at which you 

operate the PDP.

(11) Use the equations in §1066.652(a) to determine the PDP flow equation for emission testing.

(12) Verify the calibration by performing a CVS verification (i.e., propane check) as described in 

40 CFR 1065.341.

(13) Ensure that the lowest inlet pressure tested during calibration is at least as low as the lowest 

PDP inlet pressure that will occur during emission testing. You may not use the PDP below the 

lowest inlet pressure tested during calibration.

(g) SSV calibration. Calibrate a subsonic venturi (SSV) to determine its discharge coefficient,

Cd, for the expected range of inlet pressures. Calibrate an SSV flow meter as follows:

(1) Connect the system as shown in Figure 1 of this section.

(2) Verify that any leaks between the calibration flow meter and the SSV are less than 0.3 % of 

the total flow at the highest restriction.

(3) Start the blower downstream of the SSV.

(4) While the SSV operates, maintain a constant temperature at the SSV inlet within ±2 % of the 

mean absolute inlet temperature, Tin .

(5) Set the variable restrictor or variable-speed blower to a flow rate greater than the greatest 

flow rate expected during testing. You may not extrapolate flow rates beyond calibrated values, 

so we recommend that you make sure the Reynolds number, Re#, at the SSV throat at the greatest 

calibrated flow rate is greater than the maximum Re# expected during testing.

(6) Operate the SSV for at least 3 min to stabilize the system. Continue operating the SSV and 

record the mean of at least 30 seconds of sampled data of each of the following quantities:

(i) The mean flow rate of the reference flow meter,Qref

 . This may include several measurements 

of different quantities, such as reference meter pressures and temperatures, for calculatingQref

 .

(ii) The mean temperature at the venturi inlet, Tin .

(iii) The mean static absolute pressure at the venturi inlet, in p .

(iv) Static differential pressure between the static pressure at the venturi inlet and the static 

pressure at the venturi throat, SSV p .

(7) Incrementally close the restrictor valve or decrease the blower speed to decrease the flow rate.

(8) Repeat the steps in paragraphs (g)(6) and (7) of this section to record data at a minimum of 

ten flow rates.

Deleted: §

Deleted: Do

Deleted: calibration
(9) Determine a functional form of Cd versus Re# by using the collected data and the equations in 

§1066.650(b).

(10) Verify the calibration by performing a CVS verification (i.e., propane check) as described in 

40 CFR 1065.341 using the new Cd versus Re# equation.

(11) Use the SSV only between the minimum and maximum calibrated flow rates.

(12) Use the equations in §1066.652(b) to determine SSV flow during a test.

(h) CFV calibration. The calibration procedure described in this paragraph (h) establishes the 

value of the calibration coefficient at measured values of pressure, temperature and air flow.

Calibrate a critical-flow venturi (CFV) to verify its calibration coefficient, Kv, at the lowest 

expected static differential pressure between the CFV inlet and outlet. Calibrate a CFV flow 

meter as follows:

(1) Connect the system as shown in Figure 1 of this section.

(2) Verify that any leaks between the calibration flow meter and the CFV are less than 0.3 % of 

the total flow at the highest restriction.

(3) Start the blower downstream of the CFV.

(4) While the CFV operates, maintain a constant temperature at the CFV inlet within ±2 % of the 

mean absolute inlet temperature, Tin .

(5) Set the variable restrictor to its wide-open position. Instead of a variable restrictor, you may 

alternately vary the pressure downstream of the CFV by varying blower speed or by introducing 

a controlled leak. Note that some blowers have limitations on nonloaded conditions.

(6) Operate the CFV for at least 3 min to stabilize the system. Continue operating the CFV and 

record the mean values of at least 30 seconds of sampled data of each of the following quantities:

(i) The mean flow rate of the reference flow meter, Qref

 . This may include several 

measurements of different quantities, such as reference meter pressures and temperatures, for 

calculating Qref

 .

(ii) The mean temperature at the venturi inlet, Tin .

(iii) The mean static absolute pressure at the venturi inlet, in p .

(iv) The mean static differential pressure between the CFV inlet and the CFV outlet, CFV p .

(7) Incrementally close the restrictor valve or decrease the downstream pressure to decrease the 

differential pressure across the CFV, CFV p .

(8) Repeat the steps in paragraphs (f)(6) and (7) of this section to record mean data at a minimum 

of ten restrictor positions, such that you test the fullest practical range of CFV p expected during 

testing. We do not require that you remove calibration components or CVS components to 

calibrate at the lowest possible restriction.

(9) Determine Kv and the lowest allowable pressure ratio, r, according to §1066.650.

(10) Use Kv to determine CFV flow during an emission test. Do not use the CFV below the 

lowest allowed r, as determined in §1066.650.

(11) Verify the calibration by performing a CVS verification (i.e., propane check) as described in 

40 CFR 1065.341.

(12) If your CVS is configured to operate multiple CFVs in parallel, calibrate your CVS using

one of the following methods:

Deleted: §

Deleted: g

Deleted: s

Deleted: §

Deleted: more than one 

Deleted: at a time 

Deleted: by
(i) Calibrate every combination of CFVs according to this section and §1066.650(c). Refer to 

§1065.652(c) for instructions on calculating flow rates for this option.

(ii) Calibrate each CFV according to this section and §1066.650. Refer to §1066.652 for 

instructions on calculating flow rates for this option.

(i) Ultrasonic flow meter calibration. [Reserved]

Figure 1 of 1066.140—CVS calibration configurations.

reference

flow meter PDP

variable

restrictor

12

6

ref n

atmos p

in p out p Tin

PDP f

t

reference

flow meter PDP

variable

restrictor

12

6

ref n

atmos p

in p out p Tin

PDP f

t

reference

flow meter PDP

variable

restrictor

12

6

ref n

atmos p

in p out p Tin

PDP f

t

reference CFV

flow meter

variable

restrictor

ref n in p Tin

atmos p Tdew

blower

downstream

pressure

control

reference CFV

flow meter

variable

restrictor

ref n in p Tin

atmos p Tdew

blower

downstream

pressure

control

reference SSV

flow meter

ref n

atmos p

in p Tin

Tdew

p

variable speed

blower

reference SSV

flow meter

ref n

atmos p

in p Tin

Tdew

p

variable speed

blower

Deleted: 5

Deleted: 3
§1066.145 Test fuel, engine fluids, analytical gases, and other calibration standards.

(a) Test fuel. Use test fuel as specified in the standard-setting part, or as specified in 40 CFR part 

1065, subpart H, if it is not specified in the standard-setting part.

(b) Lubricating oil. Use lubricating oil as specified in 40 CFR 1065.740. For two-stroke engines 

that involve a specified mixture of fuel and lubricating oil, mix the lubricating oil with the fuel 

according to the manufacturer’s specifications.

(c) Coolant. For liquid-cooled engines, use coolant as specified in 40 CFR 1065.745.

(d) Analytical gases. Use analytical gases that meet the requirements of 40 CFR 1065.750.

(e) Mass standards. Use mass standards that meet the requirements of 40 CFR 1065.790.

§1066.150 Analyzer interference and quench verification limit.

Analyzers must meet the interference and quench verification limits in the following table on the 

lowest instrument range that will be used during emission testing, instead of those specified in 40 

CFR part 1065, subpart D:

Table 1 of §1066.150–Analyzer interference and quench verification limits.

Verification Limit

40 CFR 1065.350 ±2 % of full scale

40 CFR 1065.355 ±2 % of full scale

40 CFR 1065.370 ±2 % of full scale

40 CFR 1065.375 ±2 % of the flow-weighted mean concentration of 

N2O expected at the standard

Deleted: 0

Deleted: s

Deleted: 45

Deleted: Table 1

Deleted: in place 

Deleted: .

Deleted: 45

Deleted: 5

Deleted: of full scale
Subpart C—Dynamometer Specifications 

§1066.201 Dynamometer overview.

This subpart addresses chassis dynamometers and related equipment. 

§1066.210 Dynamometers.

(a) General requirements. A chassis dynamometer typically uses electrically generated load 

forces combined with its rotational inertia to recreate the mechanical inertia and frictional forces 

that a vehicle exerts on road surfaces (known as “road load”). Load forces are calculated using 

vehicle-specific coefficients and response characteristics. The load forces are applied to the 

vehicle tires by rolls connected to motor/absorbers. The dynamometer uses a load cell to 

measure the forces the dynamometer rolls apply to the vehicle’s tires. 

(b) Accuracy and precision. The dynamometer’s output values for road load must be NISTtraceable. We may determine traceability to a specific international standards organization to be 

sufficient to demonstrate NIST-traceability. The force-measurement system must be capable of 

indicating force readings as follows:

(1) For dynamometer testing of vehicles at or below 20,000 pounds GVWR, the dynamometer 

force-measurement system must be capable of indicating force readings during a test to a 

resolution of ±0.05 % of the maximum load-cell force simulated by the dynamometer or ±9.8 N 

(±2.2 lbf), whichever is greater.

(2) For dynamometers testing of vehicles above 20,000 pounds GVWR the force-measurement 

system must be capable of indicating force readings during a test to a resolution of ±0.05 % of 

the maximum load-cell force simulated by the dynamometer or ±39.2 N (±8.8 lbf), whichever is 

greater.

(c) Test cycles. The dynamometer must be capable of fully simulating vehicle performance over 

applicable test cycles for the vehicles being tested as referenced in the corresponding standardsetting part, including operation at the combination of inertial and road-load forces 

corresponding to maximum road load conditions and maximum simulated inertia at the highest 

acceleration rate experienced during testing.

(d) Component requirements. The following specifications apply: 

(1) The nominal roll diameter must be 120 cm or greater. The dynamometer must have an 

independent drive roll for each drive axle as tested under §1066.410(g), except that two drive 

axles may share a single drive roll. Use good engineering judgment to ensure that the 

dynamometer roll diameter is large enough to provide sufficient tire-roll contact area to avoid 

tire overheating and power losses from tire-roll slippage.

(2) Measure and record force and speed at 10 Hz or faster. You may convert measured values to 

1-Hz, 2-Hz, or 5-Hz values before your calculations, using good engineering judgment. 

(3) The load applied by the dynamometer simulates forces acting on the vehicle during normal 

driving according to the following equation: 

2 i i-1

i ii

i i-1

v v FR A B v C v M

t t

    

Eq. 1066.210-1 

Where: 

Deleted: intermediate 

Deleted: s

Deleted: capable of 

Deleted: with a GVWR 

Deleted: lbs,

Deleted: s

Deleted: 0.

Deleted: 0

Deleted: 0.

Deleted: 0

Deleted: , during a test

Deleted: capable of 

Deleted: with a

Deleted: above 20,000 lbs, 

Deleted: 

Deleted: 6

Deleted: 0

Deleted: 0

Deleted: , during a test

Deleted: ¶

(1) For vehicles with a gross vehicle weight rating 

(GVWR) at or below 14,000 lbs, the dynamometer 

must be able to fully simulate a driving schedule 

with a maximum speed of 36 m/s (80 mph) and a 

maximum acceleration rate of 3.6 m/s2

 (8 mph/s) in 

two-wheel drive and four-wheel drive configurations.¶

(2) For vehicles with GVWR above 14,000 lbs, the 

dynamometer must be able to fully simulate a 

driving schedule with a maximum speed of 29 m/s 

(65 mph) and a maximum acceleration rate of 1.3 

m/s2

 (3 mph/s) in either two-wheel drive or fourwheel drive configurations.

Deleted: dynamometer must meet the 

Deleted: .

Deleted: to 1.25 

Deleted: meters

Deleted: ou m

Deleted: ;

Deleted: you 

Deleted: use good engineering judgment to 
FR = total road-load force to be applied at the surface of the roll. The total force is the sum of 

the individual tractive forces applied at each roll surface. 

i = a counter to indicate a point in time over the driving schedule. For a dynamometer operating 

at 10-Hz intervals over a 600-second driving schedule, the maximum value of i should be 6,000. 

A = constant value representing the vehicle’s frictional load in lbf or newtons. See subpart D of 

this part. 

B = coefficient representing load from drag and rolling resistance, which are a function of 

vehicle speed, in lbf/mph or N·s/m. See subpart D of this part. 

v = linear speed at the roll surfaces as measured by the dynamometer, in mph or m/s. Let vi-1 = 0

for i = 0. 

C = coefficient representing aerodynamic effects, which are a function of vehicle speed squared, 

in lbf/mph2

 or N·s2/m2. See subpart D of this part. 

M = mass of vehicle in lbm or kg. For vehicles at or below 14,000 pounds GVWR, determine 

the vehicle’s mass based on equivalent test weight (ETW) as specified in §1066.810 and set 

dynamometer inertia simulation as specified in §1066.410(h). For vehicles above 14,000 pounds 

GVWR, determine the vehicle’s mass based on the test weight, taking into account the effect of 

rotating axles, as specified in §1066.310(b)(7) and dividing the weight by the acceleration due to 

gravity as specified in 40 CFR 1065.630, consistent with good engineering judgment. 

t = elapsed time in the driving schedule as measured by the dynamometer, in seconds. Let ti-1 = 0

for i = 0. 

(4) We recommend that a dynamometer capable of testing vehicles at or below 20,000 pounds 

GVWR be designed to apply an actual road-load force within ±1 % or ±9.8 N (±2.2 lbf) of the 

reference value, whichever is greater. Dynamometers that do not fully meet this specification 

may be used consistent with good engineering judgment. For example, slightly higher errors 

may be permissible during highly transient operation for vehicles with a GVWR above 8500 

pounds. 

(e) Dynamometer manufacturer instructions. This part specifies that you follow the dynamometer 

manufacturer’s recommended procedures for things such as calibrations and general operation. 

If you perform testing with a dynamometer that you manufactured or if you otherwise do not 

have these recommended procedures, use good engineering judgment to establish the additional 

procedures and specifications we specify in this part, unless we specify otherwise. Keep records 

to describe these recommended procedures and how they are consistent with good engineering 

judgment, including any quantified error estimates.

§1066.215 Summary of verification and calibration procedures for chassis dynamometers. 

(a) Overview. This section describes the overall process for verifying and calibrating the 

performance of chassis dynamometers.

(b) Scope and frequency. The following table summarizes the required and recommended 

calibrations and verifications described in this subpart and indicates when they must occur: 

Table 1 of §1066.215–Summary of required dynamometer calibrations and verifications. 

Type of calibration or verification Minimum frequencya

§1066.220: Linearity verification 

Speed: Upon initial installation, within 370 days before testing, and after 

major maintenance. 

Torque (load): Upon initial installation and after major maintenance. 

§1066.225: Roll runout and diameter

verification Upon initial installation and after major maintenance. 

§1066.230: Time verification Upon initial installation and after major maintenance. 

Deleted: is 

Deleted: C 

Deleted: C 

Deleted: S

Deleted: Si

Deleted: C 

Deleted: with GVWR 

Deleted: lbs

Deleted: ,

Deleted: with GVWR 

Deleted: lbs

Deleted: D

Deleted: The 

Deleted: the

Deleted: must be

Deleted: is

Deleted: generally 

Deleted: , within 370 days before testing,
§1066.235: Speed measurement

verification

Upon initial installation, within 370 days before testing, and after major 

maintenance. 

§1066.240: Torque (load) transducer

verification Upon initial installation, within 7 days of testing, and after major maintenance. 

§1066.245: Response time

verification

Upon initial installation, within 370 days before testing, and after major 

maintenance. 

§1066.250: Base inertia verification Upon initial installation and after major maintenance. 

§1066.255: Parasitic loss verification Upon initial installation, after major maintenance, and upon failure of a

verification in §1066.270 or §1066.280. 

§1066.260: Parasitic friction 

compensation evaluation 

Upon initial installation, after major maintenance, and upon failure of a

verification in §1066.270 or §1066.280. 

§1066.265: Acceleration and 

deceleration verification Upon initial installation and after major maintenance. 

§1066.270: Unloaded coastdown

verification Upon initial installation, within 7 days of testing, and after major maintenance. 

§1066.280 Dynamometer readiness 

verification

Upon initial installation, within 1 day before testing, and after major 

maintenance. a

Perform calibrations and verifications more frequently, according to measurement system manufacturer instructions 

and good engineering judgment. 

(c) Automated dynamometer verifications and calibrations. In some cases, dynamometers are 

designed with internal diagnostic and control features to accomplish the verifications and 

calibrations specified in this subpart. You may use these automated functions instead of 

following the procedures we specify in this subpart to demonstrate compliance with applicable 

requirements, consistent with good engineering judgment. 

(d) Sequence of verifications and calibrations. Upon initial installation and after major 

maintenance, perform the verifications and calibrations in the same sequence as noted in Table 1 

of this section, except that you may perform speed linearity verification after the verifications in 

§§1066.225 and 1066.230. At other times, you may need to perform specific verifications or 

calibrations in a certain sequence, as noted in this subpart. If you perform major maintenance on 

a specific component, you are required to perform verifications and calibrations only on 

components or parameters that are affected by the maintenance.

(e) Corrections. Unless the regulation directs otherwise, if the dynamometer fails to meet any 

specified calibration or verification, make any necessary adjustments or repairs such that the 

dynamometer meets the specification before running a test. Repairs required to meet 

specifications are generally considered major maintenance under this part. 

§1066.220 Linearity verification for chassis dynamometer systems. 

(a) Scope and frequency. Perform linearity verification for dynamometer speed and torque at 

least as frequently as indicated in Table 1 of §1066.215. The intent of linearity verification is to 

determine that the system responds accurately and proportionally over the measurement range of 

interest. Linearity verification generally consists of introducing a series of at least 10 reference 

values to a measurement system. The measurement system quantifies each reference value. The 

measured values are then collectively compared to the reference values by using a least-squares 

linear regression and the linearity criteria specified in Table 1 of this section. 

(b) Performance requirements. If a measurement system does not meet the applicable linearity 

criteria in Table 1 of this section, correct the deficiency by re-calibrating, servicing, or replacing 

components as needed. Repeat the linearity verification after correcting the deficiency to ensure 

that the measurement system meets the linearity criteria. Before you may use a measurement 

system that does not meet linearity criteria, you must demonstrate to us that the deficiency does 

not adversely affect your ability to demonstrate compliance with the applicable standards. 

Deleted: within 7 days before testing, and 

Deleted: the

Deleted: s

Deleted: within 7 days before testing, and 

Deleted: the

Deleted: s

Deleted: before 

Deleted: 3 hours

Deleted: . Speed 

Deleted: may be performed 

Deleted: performing 

Deleted: a measurement 
(c) Procedure. Use the following linearity verification protocol, or use good engineering 

judgment to develop a different protocol that satisfies the intent of this section, as described in 

paragraph (a) of this section: 

(1) In this paragraph (c), the letter “y” denotes a generic measured quantity, the superscript overbar denotes an arithmetic mean (such as y ), and the subscript “ref” denotes the known or 

reference quantity being measured. 

(2) Operate the dynamometer system at the specified operating conditions. This may include any 

specified adjustment or periodic calibration of the dynamometer system. 

(3) Set dynamometer speed and torque to zero. 

(4) Verify the dynamometer speed or torque signal based on the dynamometer manufacturer’s 

recommendations. 

(5) After verification, check for zero speed and torque. Use good engineering judgment to 

determine whether or not to rezero or re-verify speed and torque before continuing. 

(6) For both speed and torque, use the dynamometer manufacturer’s recommendations and good 

engineering judgment to select reference values, yrefi, that cover a range of values that you expect 

would prevent extrapolation beyond these values during emission testing. We recommend 

selecting zero speed and zero torque as reference values for the linearity verification. 

(7) Use the dynamometer manufacturer’s recommendations and good engineering judgment to 

select the order in which you will introduce the series of reference values. For example, you 

may select the reference values randomly to avoid correlation with previous measurements and 

to avoid the influence of hysteresis; you may select reference values in ascending or descending 

order to avoid long settling times of reference signals; or you may select values to ascend and 

then descend to incorporate the effects of any instrument hysteresis into the linearity verification. 

(8) Set the dynamometer to operate at a reference condition. 

(9) Allow time for the dynamometer to stabilize while it measures the reference values. 

(10) At a recording frequency of at least 1 Hz, measure speed and torque values for 30 seconds 

and record the arithmetic mean of the recorded values, i y . Refer to 40 CFR 1065.602 for an 

example of calculating an arithmetic mean. 

(11) Repeat the steps in paragraphs (c)(8) though (10) of this section until you measure speeds 

and torques at each of the reference settings. 

(12) Use the arithmetic means, i y , and reference values, yrefi , to calculate least-squares linear 

regression parameters and statistical values to compare to the minimum performance criteria 

specified in Table 1 of this section. Use the calculations described in 40 CFR 1065.602. Using 

good engineering judgment, you may weight the results of individual data pairs (i.e., (yrefi, i y )), 

in the linear regression calculations. Table 1 follows:

Table 1 of §1066.220– 

Dynamometer measurement systems that require linearity verifications 

Measurement 

system Quantity Linearity criteria 

| ymin(a1-1)+a0 | a1 SEE r

2

Speed v <0.05 % · max v 0.98-1.02 <2 % · max v >0.990 

Torque (load) T <1 % · Tmax 0.99-1.01 <1 % · Tmax >0.990 

(d) Reference signals. Generate reference values for the linearity-verification protocol in 

paragraph (c) of this section as described for speed and torque in 40 CFR 1065.307(d). 

Deleted: a 

Deleted: temperatures and pressures

Deleted: and apply the dynamometer brake to 

ensure a zero-speed condition

Deleted: Span 

Deleted: spanning

Deleted: span 

Deleted: or 

Deleted: conditions

Deleted: x

Deleted: S

Deleted: 98

Deleted: 02

Deleted: 2 
§1066.225 Roll runout and diameter verification procedure. 

(a) Overview. This section describes the verification procedure for roll runout and roll diameter. 

Roll runout is a measure of the variation in roll radius around the circumference of the roll. 

(b) Scope and frequency. Perform these verifications upon initial installation and after major 

maintenance that could affect roll surface finish or dimensions (such as resurfacing or polishing). 

(c) Roll runout procedure. Verify roll runout based on the following procedure, or an equivalent 

procedure based on good engineering judgment: 

(1) Perform this verification with laboratory and dynamometer temperatures stable and at 

equilibrium. Release the roll brake and shut off power to the dynamometer. Remove any dirt, 

rubber, rust, and debris from the roll surface. Mark measurement locations on the roll surface 

using a permanent marker. Mark the roll at a minimum of four equally spaced locations across 

the roll width; we recommend taking measurements every 150 mm across the roll. Secure the 

marker to the deck plate adjacent to the roll surface and slowly rotate the roll to mark a clear line 

around the roll circumference. Repeat this process for all measurement locations. 

(2) Measure roll runout using an indicator with a probe that allows for measuring the position of 

the roll surface relative to the roll centerline as it turns through a complete revolution. The 

indicator must have some means of being securely mounted adjacent to the roll. The indicator 

must have sufficient range to measure roll runout at all points, with a minimum accuracy and 

precision of ±0.025 mm. Calibrate the indicator according to the instrument manufacturer’s 

instructions. 

(3) Position the indicator adjacent to the roll surface at the desired measurement location. 

Position the shaft of the indicator perpendicular to the roll such that the point of the indicator is 

slightly touching the surface of the roll and can move freely through a full rotation of the roll. 

Zero the indicator according to the instrument manufacturer’s instructions. Avoid distortion of 

the runout measurement from the weight of a person standing on or near the mounted dial 

indicator. 

(4) Slowly turn the roll through a complete rotation and record the maximum and minimum 

values from the indicator. Calculate runout as the difference between these maximum and 

minimum values. 

(5) Repeat the steps in paragraphs (c)(3) and (4) of this section for all measurement locations. 

(6) The roll runout must be less than 0.254 mm (0.0100 inches) at all measurement locations. 

(d) Diameter procedure. Verify roll diameter based on the following procedure, or an equivalent 

procedure based on good engineering judgment: 

(1) Prepare the laboratory and the dynamometer as specified in paragraph (c)(1) of this section. 

(2) Measure roll diameter using a Pi Tape®. Orient the Pi Tape® to the marker line at the 

desired measurement location with the Pi Tape® hook pointed outward. Temporarily secure the 

Pi Tape® to the roll near the hook end with adhesive tape. Slowly turn the roll, wrapping the Pi 

Tape® around the roll surface. Ensure that the Pi Tape® is flat and adjacent to the marker line 

around the full circumference of the roll. Attach a 2.26-kg weight to the hook of the Pi Tape® 

and position the roll so that the weight dangles freely. Remove the adhesive tape without 

disturbing the orientation or alignment of the Pi Tape®. 

(3) Overlap the gage member and the vernier scale ends of the Pi Tape® to read the diameter 

measurement to the nearest 0.01 mm. Follow the manufacturer’s recommendation to correct the 

measurement to 20 °C, if applicable. 

(4) Repeat the steps in paragraphs (d)(2) and (3) of this section for all measurement locations. 

Deleted: dial 

Deleted: dial 

Deleted: a magnetic base assembly or other

Deleted: dial 

Deleted: dial 

Deleted: dial 

Deleted: dial 

Deleted: dial 

Deleted: dial 

Deleted: dial 
(5) The measured roll diameter must be within ±0.254 mm of the specified nominal value at all 

measurement locations. You may revise the nominal value to meet this specification, as long as 

you use the corrected nominal value for all calculations in this subpart. 

§1066.230 Time verification procedure. 

(a) Overview. This section describes how to verify the accuracy of the dynamometer’s timing 

device. 

(b) Scope and frequency. Perform this verification upon initial installation and after major 

maintenance. 

(c) Procedure. Perform this verification using one of the following procedures: 

(1) WWV method. You may use the time and frequency signal broadcast by NIST from radio 

station WWV as the time standard if the trigger for the dynamometer timing circuit has a 

frequency decoder circuit, as follows: 

(i) Dial station WWV at (303) 499-7111 and listen for the time announcement. Verify that the 

trigger started the dynamometer timer. Use good engineering judgment to minimize error in 

receiving the time and frequency signal. 

(ii) After at least 1000 seconds, re-dial station WWV and listen for the time announcement. 

Verify that the trigger stopped the dynamometer timer. 

(iii) Compare the measured elapsed time, yact, to the corresponding time standard, yref, to 

determine the time error, yerror, using the following equation: 

act ref

error

ref

100 % y y y

y

  

Eq. 1066.230-1 

(2) Ramping method. You may set up an operator-defined ramp function to serve as the time 

standard as follows: 

(i) Set up the signal generator to output a marker voltage at the peak of each ramp to trigger the 

dynamometer timing circuit. Output the designated marker voltage to start the verification 

period. 

(ii) After at least 1000 seconds, output the designated marker voltage to end the verification 

period. 

(iii) Compare the measured elapsed time between marker signals, yact, to the corresponding time 

standard, yref, to determine the time error, yerror, using Eq. 1066.230-1. 

(3) Dynamometer coastdown method. You may use a signal generator to output a known speed 

ramp signal to the dynamometer controller to serve as the time standard as follows: 

(i) Generate upper and lower speed values to trigger the start and stop functions of the coastdown 

timer circuit. Use the signal generator to start the verification period. 

(ii) After at least 1000 seconds, use the signal generator to end the verification period. 

(iii) Compare the measured elapsed time between trigger signals, yact, to the corresponding time 

standard, yref, to determine the time error, yerror, using Eq. 1066.230-1. 

(d) Performance evaluation. The time error determined in paragraph (c) of this section may not 

exceed ±0.001 %. 

§1066.235 Speed verification procedure. 

(a) Overview. This section describes how to verify the accuracy and resolution of the 

dynamometer speed determination. When performing this verification, you must also verify the 

Deleted: in the signal generator 

Deleted: Equation

Deleted: Equation
dynamometer speed at any devices used to display or record vehicle speed (for example a 

driver’s aid) is representative of the speed input from the dynamometer speed determination.

(b) Scope and frequency. Perform this verification upon initial installation, within 370 days 

before testing, and after major maintenance. 

(c) Procedure. Use one of the following procedures to verify the accuracy and resolution of the 

dynamometer speed simulation: 

(1) Pulse method. Connect a universal frequency counter to the output of the dynamometer’s 

speed-sensing device in parallel with the signal to the dynamometer controller. The universal 

frequency counter must be calibrated according to the instrument manufacturer’s instructions and 

be capable of measuring with enough accuracy to perform the procedure as specified in this 

paragraph (c)(1). Make sure the instrumentation does not affect the signal to the dynamometer 

control circuits. Determine the speed error as follows: 

(i) Set the dynamometer to speed-control mode. Set the dynamometer speed to a value of 

approximately 4.5 m/s (10 mph); record the output of the frequency counter after 10 seconds. 

Determine the roll speed, vact, using the following equation: 

roll

act

f d v n

  

 Eq. 1066.235-1 

Where: 

f = frequency of the dynamometer speed sensing device, accurate to at least four significant 

figures. 

droll = nominal roll diameter, accurate to the nearest 1.0 mm, consistent with §1066.225(d). 

n = the number of pulses per revolution from the dynamometer roll speed sensor. 

Example:

f = 2.9231 Hz = 2.9231 s-1 

droll = 904.40 mm = 0.90440 m 

n = 1 pulse/rev 

act

2.9231 0.90440

1 v   

vact = 8.3053 m/s 

(ii) Repeat the steps in paragraph (c)(1)(i) of this section for the maximum speed expected during 

testing and at least two additional evenly spaced speed points between the starting speed and the 

maximum speed point.

(iii) Compare the calculated roll speed, vact, to each corresponding speed set point, vref, to 

determine values for speed error at each set point, verror, using the following equation: 

verror = vact - vref

Eq. 1066.235-2 

Example:

vact = 8.3053 m/s 

vref = 8.3000 m/s 

verror = 8.3053 – 8.3000 = 0.0053 m/s

Deleted: between 

Deleted: 2 

Deleted: and the maximum speed expected during 

testing

Deleted: Sact

Deleted: , in s-1

Deleted: , in m

Deleted: 0.01 

Deleted: Sact

Deleted: three 

Deleted: expected during testing. The maximum 

speed point should be considered one of these points

Deleted: Sact

Deleted: the 

Deleted: Sref

Deleted: Serror

Deleted: Serror 

Deleted: Sact 

Deleted: Sref

Deleted: Sact

Deleted: Sref

Deleted: Serror 
(2) Frequency method. Install a piece of tape in the shape of an arrowhead on the surface of the 

dynamometer roll near the outer edge. Put a reference mark on the deck plate in line with the 

tape. Install a stroboscope or photo tachometer on the deck plate and direct the flash toward the 

tape on the roll. The stroboscope or photo tachometer must be calibrated according to the 

instrument manufacturer’s instructions and be capable of measuring with enough accuracy to 

perform the procedure as specified in this paragraph (c)(2). Determine the speed error as 

follows: 

(i) Set the dynamometer to speed control mode. Set the dynamometer speed to a speed value of

approximately 4.5 m/s (10 mph). Tune the stroboscope or photo tachometer until the signal 

matches the dynamometer roll speed. Record the frequency. Determine the roll speed, yact, 

using Eq. 1066.235-1, using the stroboscope or photo tachometer’s frequency for f. 

(ii) Repeat the steps in paragraph (c)(2)(i) of this section for the maximum speed expected during 

testing and at least two additional evenly spaced speed points between the starting speed and the 

maximum speed point.

(iii) Compare the calculated roll speed, vact, to each corresponding speed set point, vref, to 

determine values for speed error at each set point, yerror, using Eq. 1066.235-2.

(d) Performance evaluation. The speed error determined in paragraph (c) of this section may not 

exceed ±0.02 m/s at any speed set point. 

§1066.240 Torque transducer verification. 

Verify torque-measurement systems by performing the verifications described in §1066.270 and 

280. 

§1066.245 Response time verification. 

(a) Overview. This section describes how to verify the dynamometer’s response time. 

(b) Scope and frequency. Perform this verification upon initial installation, within 370 days 

before testing, and after major maintenance. 

(c) Procedure. Use the dynamometer’s automated process to verify response time. You may 

perform this test either at two different inertia settings corresponding approximately to the 

minimum and maximum vehicle weights you expect to test or using base inertia and two 

acceleration rates that cover the range of acceleration rates experienced during testing (for 

example 0.5 and 8 mph/s). Use good engineering judgment to select road-load coefficients 

representing vehicles of the appropriate weight. Determine the dynamometer’s settling response 

time, ts, based on the point at which there are no measured results more than 10 % above or 

below the final equilibrium value, as illustrated in Figure 1 of this section. The observed settling 

response time must be less than 100 milliseconds for each inertia setting. 

Deleted: Use the method described in this 

paragraph (c)(2) only if the dynamometer does not 

have a readily available output signal for speed 

sensing. 

Deleted: single 

Deleted: arrow

Deleted: between 

Deleted: 15 kph and the maximum speed expected 

during testing

Deleted: Equation

Deleted: at least three additional evenly spaced 

speed points between the starting speed and the 

maximum speed expected during testing. The 

maximum speed point should be considered one of 

these points

Deleted: y

Deleted: the 

Deleted: y

Deleted: a 

Deleted: v

Deleted: Equation

Deleted: (0.05 mph) 

Deleted: and calibration

Deleted: Calibrate 

Deleted: as 

Deleted: 40 CFR

Deleted: 

Deleted: 5

Deleted: 310

Deleted: Perform 
Figure 1 of §1066.245—Example of a settling response time diagram. 

Time (t)

ts

Response

1.1

1.0

0.9

§1066.250 Base inertia verification. 

(a) Overview. This section describes how to verify the dynamometer’s base inertia. 

(b) Scope and frequency. Perform this verification upon initial installation and after major 

maintenance (such as maintenance that could affect roll assembly inertia). 

(c) Procedure. Verify the base inertia using the following procedure: 

(1) Warm up the dynamometer according to the dynamometer manufacturer’s instructions. Set 

the dynamometer’s road-load inertia to zero, turning off any electrical simulation of road load 

and inertia so that the base inertia of the dynamometer is the only inertia present, and motor the 

rolls to 5 mph. Apply a constant force to accelerate the roll at a nominal rate of 1 mph/s. 

Measure the elapsed time to accelerate from 10 to 40 mph, noting the corresponding speed and 

time points to the nearest 0.01 mph and 0.01 s. Also determine average force over the 

measurement interval. 

(2) Starting from a steady roll speed of 45 mph, apply a constant force to the roll to decelerate 

the roll at a nominal rate of 1 mph/s. Measure the elapsed time to decelerate from 40 to 10 mph, 

noting the corresponding speed and time points to the nearest 0.01 mph and 0.01 s. Also 

determine average force over the measurement interval. 

(3) Repeat the steps in paragraphs (c)(1) and (2) of this section for a total of five sets of results at 

the nominal acceleration rate and the nominal deceleration rate. 

(4) Use good engineering judgment to select two additional acceleration and deceleration rates 

that cover the middle and upper rates expected during testing. Repeat the steps in paragraphs 

(c)(1) through (3) of this section at each of these additional acceleration and deceleration rates. 

(5) Determine the base inertia, Ib, for each measurement interval using the following equation: 
b

final initial

F I v v

t

 



Eq. 1066.250-1 

Where: 

F = average dynamometer force over the measurement interval as measured by the dynamometer.

vfinal = roll surface speed at the end of the measurement interval to the nearest 0.01 mph. 

vinitial = roll surface speed at the start of the measurement interval to the nearest 0.01 mph. 

t = elapsed time during the measurement interval to the nearest 0.01 s. 

Example:

F = 1.500 lbf = 48.26 ft·lbm/s2 

vfinal = 40.00 mph = 58.67 ft/s 

vinitial = 10.00 mph = 14.67 ft/s 

t = 30.00 s 

b

48.26

58.67 14.67

30.00

I  

Ib = 32.90 lbm 

(6) Calculate the base inertia error, Iberror, for each of the thirty measured base inertia values, Ib, 

by comparing it to the manufacturer’s stated base inertia, Ibref, using the following equation: 

bref bact

berror

bref

100 % I I I

I

  

Eq. 1066.250-2 

Example:

Ibref = 32.96 lbm 

bact I = 32.90 lbm (from paragraph (c)(5) of this section)

berror

32.96 32.90 100 %

32.96

I   

Iberror = 0.18 % 

(7) Determine the base inertia arithmetic mean value, b I , from the ten acceleration and 

deceleration interval base inertia values for each of the three acceleration/deceleration rates. 

Then determine the base inertia arithmetic mean value, b I , from the three 

acceleration/deceleration rate mean base inertia values. Calculate base inertia mean values as 

described in 40 CFR 1065.602(b)

(8) Calculate the inertia error for the final mean base inertia value from paragraph (c)(7) of this 

section. Use Eq. 1066.250-2, substituting the final mean base inertia value from paragraph (c)(7) 

of this section for the individual base inertia. 

Deleted: , in ft·lbm/s2

Deleted: Sfinal

Deleted: Sinitial

Deleted: Sfinal

Deleted: Sinitial

Deleted: (6) Determine the arithmetic mean value 

of base inertia from the five measurements at each 

acceleration and deceleration rate. Calculate these 

six mean values as described in 40 CFR 1065.602(b). 

Deleted: 7

Deleted: 33

Deleted: 01 

Deleted: –

Deleted: 15 

Deleted: sum of the 

Deleted: each of 

Deleted: three 

Deleted: s of base inertia

Deleted: 6

Deleted: Equation

Deleted: 265

Deleted: s

Deleted: associated with each acceleration and 

deceleration rate

Deleted: s
(d) Performance evaluation. The dynamometer must meet the following specifications to be used 

for testing under this part: 

(1) All base inertia errors determined under paragraph (c)(6) of this section may not exceed 

±1.0 %. 

(2) The mean base inertia error determined under paragraph (c)(8) of this section may not exceed 

±0.20 %. 

§1066.255 Parasitic loss verification. 

(a) Overview. Verify and correct the dynamometer’s parasitic loss. This procedure determines 

the dynamometer’s internal losses that it must overcome to simulate road load. These losses are 

characterized in a parasitic loss curve that the dynamometer uses to apply compensating forces to 

maintain the desired road-load force at the roll surface. 

(b) Scope and frequency. Perform this verification upon initial installation, after major 

maintenance, and upon failure of a verification in either §1066.270 or §1066.280. 

(c) Procedure. Perform this verification by following the dynamometer manufacturer’s 

specifications to establish a parasitic loss curve, taking data at fixed speed intervals to cover the 

range of vehicle speeds that will occur during testing. You may zero the load cell at a selected 

speed if that improves your ability to determine the parasitic loss. Parasitic loss forces may 

never be negative. Note that the torque transducers must be zeroed and spanned prior to 

performing this procedure. 

(d) Performance evaluation. In some cases, the dynamometer automatically updates the parasitic 

loss curve for further testing. If this is not the case, compare the new parasitic loss curve to the 

original parasitic loss curve from the dynamometer manufacturer or the most recent parasitic loss 

curve you programmed into the dynamometer. You may reprogram the dynamometer to accept 

the new curve in all cases, and you must reprogram the dynamometer if any point on the new 

curve departs from the earlier curve by more than ±9.0 N for dynamometers capable of testing 

vehicles at or below 20,000 pounds GVWR or ±36.0 N (±8.0 lbf) for dynamometers not capable 

of testing vehicles at or below 20,000 pounds GVWR. 

§1066.260 Parasitic friction compensation evaluation. 

(a) Overview. This section describes how to verify the accuracy of the dynamometer’s friction 

compensation. 

(b) Scope and frequency. Perform this verification upon initial installation, after major 

maintenance, and upon failure of a verification in either §1066.270 or §1066.280. Note that this 

procedure relies on proper verification or calibration of speed and torque, as described in 

§§1066.235 and 1066.240. You must also first verify the dynamometer’s parasitic loss curve as 

specified in §1066.255. 

(c) Procedure. Use the following procedure to verify the accuracy of the dynamometer’s friction 

compensation: 

(1) Warm up the dynamometer as specified by the dynamometer manufacturer. 

(2) Perform a torque verification as specified by the dynamometer manufacturer. For torque 

verifications relying on shunt procedures, if the results do not conform to specifications, 

recalibrate the dynamometer using NIST-traceable standards as appropriate until the 

dynamometer passes the torque verification. Do not change the dynamometer’s base inertia to 

pass the torque verification. 

Deleted: The 

Deleted: 7

Deleted: 0.50

Deleted: relative to any individual value

Deleted: The 

Deleted: All

Deleted: s

Deleted: relative to any mean value

Deleted: within 7 days of testing, and 

Deleted: the

Deleted: s

Deleted: the 

Deleted: 4.5

Deleted: (±

Deleted: 1

Deleted: 2.0 lbf)

Deleted: with a GVWR 

Deleted: lbs,

Deleted: with a GVWR 

Deleted: above 

Deleted: lbs

Deleted: within 7 days before testing, and 

Deleted: the

Deleted: s
(3) Set the dynamometer inertia to the base inertia with the road-load coefficients A, B, and C set 

to 0. Set the dynamometer to speed-control mode with a target speed of 50 mph or a higher 

speed recommended by the dynamometer manufacturer. Once the speed stabilizes at the target 

speed, switch the dynamometer from speed control to torque control and allow the roll to coast 

for 60 seconds. Record the initial and final speeds and the corresponding start and stop times. If 

friction compensation is executed perfectly, there will be no change in speed during the 

measurement interval. 

(4) Calculate the power equivalent of friction compensation error, FCerror, using the following 

equation: 

  2 2

error init final 2

I FC v v

t   

Eq. 1066.260-1 

Where: 

I = dynamometer inertia setting. 

t = duration of the measurement interval, accurate to at least 0.01 s. 

vinit = the roll speed corresponding to the start of the measurement interval, accurate to at least 

0.05 mph.

vfinal = the roll speed corresponding to the end of the measurement interval, accurate to at least 

0.05 mph. 

Example:

I = 2000 lbm = 62.16 lbf· s2

/ft 

t = 60.0 s 

vinit = 9.2 mph = 13.5 ft/s 

vfinal = 10.0 mph = 14.7 ft/s 

  2 2

error

62.16 13.5 14.7

2 60.00

FC   

FCerror = –16.5 ft·lbf/s = –0.031 hp 

(5) The friction compensation error may not exceed ±0.15 hp for dynamometers capable of 

testing vehicles at or below 20,000 pounds GVWR, or ±0.6 hp for dynamometers not capable of 

testing vehicles at or below 20,000 pounds GVWR. 

§1066.265 Acceleration and deceleration verification. 

(a) Overview. This section describes how to verify the dynamometer’s ability to achieve 

targeted acceleration and deceleration rates. Paragraph (c) of this section describes how this 

verification applies when the dynamometer is programmed directly for a specific acceleration or 

deceleration rate. Paragraph (d) of this section describes how this verification applies when the 

dynamometer is programmed with a calculated force to achieve a targeted acceleration or 

deceleration rate. 

(b) Scope and frequency. Perform this verification or an equivalent procedure upon initial 

installation and after major maintenance that could affect acceleration and deceleration accuracy. 

Note that this procedure relies on proper verification or calibration of speed as described in 

§1066.235.

(c) Verification of acceleration and deceleration rates. Activate the dynamometer’s function 

generator for measuring roll revolution frequency. If the dynamometer has no such function 

Deleted: 10 

Deleted: , in lbf·s2/ft

Deleted: 1

Deleted: Sfinal

Deleted: 01 

Deleted: Sinit = the roll speed corresponding to the 

start of the measurement interval, accurate to at least 

0.1 mph.¶

Deleted: Sfinal

Deleted: Sinit

Deleted: with a GVWR 

Deleted: lbs

Deleted: with a GVWR above 

Deleted: lbs
generator, set up a properly calibrated external function generator consistent with the verification 

described in this paragraph (c). Use the function generator to determine actual acceleration and 

deceleration rates as the dynamometer traverses speeds between 10 and 40 mph at various 

nominal acceleration and deceleration rates. Verify the dynamometer’s acceleration and 

deceleration rates as follows: 

(1) Set up start and stop frequencies specific to your dynamometer by identifying the rollrevolution frequency, f, in revolutions per second (or Hz) corresponding to 10 mph and 40 mph 

vehicle speeds, accurate to at least four significant figures, using the following equation: 

roll

v n f d 

  

Eq. 1066.265-1 

Where: 

v = the target roll speed, in inches per second (corresponding to drive speeds of 10 mph or 40 

mph). 

n = the number of pulses from the dynamometer’s roll-speed sensor per roll revolution. 

droll = roll diameter, in inches. 

(2) Program the dynamometer to accelerate the roll at a nominal rate of 1 mph/s from 10 mph to 

40 mph. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. Repeat this 

measurement for a total of five runs. Determine the actual acceleration rate for each run, aact, 

using the following equation: 

final init

act

v v a t

 

Eq. 1066.265-2 

Where: 

aact = acceleration rate (decelerations have negative values). 

vfinal = the target value for the final roll speed. 

vinit = the setpoint value for the initial roll speed. 

t = time to accelerate from vinit to vfinal. 

Example:

vfinal = 40 mph 

vinit = 10 mph 

t = 30.003 s 

act

40.00 10.00

30.03 a  

aact = 0.999 mph/s 

(3) Program the dynamometer to decelerate the roll at a nominal rate of 1 mph/s from 40 mph to 

10 mph. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. Repeat this 

measurement for a total of five runs. Determine the actual acceleration rate, aact, using Eq.

1066.265-2 

(4) Repeat the steps in paragraphs (c)(2) and (3) of this section for additional acceleration and 

deceleration rates in 1 mph/s increments up to and including one increment above the maximum 

Deleted: S

Deleted: Sfinal

Deleted: Sinit

Deleted: Sinit

Deleted: Sfinal

Deleted: Sinal

Deleted: Sinit

Deleted: Equation
acceleration rate expected during testing. Average the five repeat runs to calculate a mean 

acceleration rate, act a , at each setting. 

(5) Compare each mean acceleration rate, act a , to the corresponding nominal acceleration rate, 

aref, to determine values for acceleration error, aerror, using the following equation: 

act ref

error

ref

100 % a a a a

  

Eq. 1066.265-3 

Example:

act a = 0.999 mph/s 

aref = 1 mph/s

error

0.999 1 100 %

1 a   

aerror = –0.100 % 

(d) Verification of forces for controlling acceleration and deceleration. Program the 

dynamometer with a calculated force value and determine actual acceleration and deceleration 

rates as the dynamometer traverses speeds between 10 and 40 mph at various nominal 

acceleration and deceleration rates. Verify the dynamometer’s ability to achieve certain 

acceleration and deceleration rates with a given force as follows: 

(1) Calculate the force setting, F, using the following equation: 

F b   I a

Eq. 1066.265-4 

Where: 

Ib = the dynamometer manufacturer’s stated base inertia, in lbf·s2

/ft. 

a = nominal acceleration rate, in ft/s2

. 

Example:

Ib = 2967 lbm = 92.217 lbf· s2

/ft

a = 1 mph/s = 1.4667 ft/s2 

F   92.217 1.4667

F = 135.25 lbf

(2) Set the dynamometer to road-load mode and program it with a calculated force to accelerate 

the roll at a nominal rate of 1 mph/s from 10 mph to 40 mph. Measure the elapsed time to reach 

the target speed, to the nearest 0.01 s. Repeat this measurement for a total of five runs. 

Determine the actual acceleration rate, aact, for each run using Eq. 1066.265-2. Repeat this step 

to determine measured “negative acceleration” rates using a calculated force to decelerate the 

roll at a nominal rate of 1 mph/s from 40 mph to 10 mph. Average the five repeat runs to 

calculate a mean acceleration rate, act a , at each setting. 

(3) Repeat the steps in paragraph (d)(2) of this section for additional acceleration and 

deceleration rates as specified in paragraph (c)(4) of this section. 

Deleted: Equation
(4) Compare each mean acceleration rate, act a , to the corresponding nominal acceleration rate, 

aref, to determine values for acceleration error, aerror, using Eq. 1066.265-3

(e) Performance evaluation. The acceleration error from paragraphs (c)(5) and (d)(4) of this 

section may not exceed ±1.0 %. 

§1066.270 Unloaded coastdown verification. 

(a) Overview. Use force measurements to verify the dynamometer’s settings based on 

coastdown procedures. 

(b) Scope and frequency. Perform this verification upon initial installation, within 7 days of 

testing, and after major maintenance. 

(c) Procedure. This procedure verifies the dynamometer’s settings derived from coastdown 

testing. For dynamometers that have an automated process for this procedure, perform this 

evaluation by setting the initial speed, final speed, inertial coefficients, and road-load coefficients 

as required for each test, using good engineering judgment to ensure that these values properly 

represent in-use operation. Use the following procedure if your dynamometer does not perform 

this verification with an automated process: 

(1) Warm up the dynamometer as specified by the dynamometer manufacturer. 

(2) With the dynamometer in coastdown mode, set the dynamometer inertia for the smallest 

vehicle weight that you expect to test and set A, B, and C road-load coefficients to values typical 

of those used during testing. Program the dynamometer to coast down over the dynamometer 

operational speed range (typically from a speed of 80 mph through a minimum speed at or below

10 mph). Perform at least one coastdown over this speed range, collecting data over each 10 

mph interval. 

(3) Repeat the steps in paragraph (c)(2) of this section with the dynamometer inertia and roadload coefficients set for the largest vehicle weight that you expect to test. 

(4) Determine the average coastdown force, F, for each speed and inertia setting for each of the 

coastdowns performed using the following equation: 

Iv v  init final F

t

  

Eq. 1066.270-1 

Where: 

F = the average force measured during the coastdown for each speed interval and inertia setting, 

expressed in lbf· s2/ft and rounded to four significant figures.

I = the dynamometer’s inertia setting, in lbf· s2

/ft. 

vinit = the speed at the start of the coastdown, expressed in ft/s and rounded to four significant 

figures.

vfinal = the speed at the end of the coastdown interval, rounded to four significant figures.

t = coastdown time for each speed and inertia setting, accurate to at least 0.01 s. 

Example:

I = 2000 lbm = 65.17 lbf · s2

/ft

vinit = 25 mph = 36.66 ft/s

vfinal = 15 mph = 22.0 ft/s

t = 5.00 s 

Deleted: Equation

Deleted: 4

Deleted: and 

Deleted: and the 

Deleted: operate at 10 mph

Deleted: two times 

Deleted: at this 

Deleted: setting

Deleted: Repeat these coastdown steps in 10 mph 

increments up to and including one increment above 

the maximum speed expected during testing. You 

may stop the verification before reaching 0 mph, 

with any appropriate adjustments in calculating the 

results.

Deleted: Ssi

Deleted: setting 

Deleted: Ssi

Deleted: 10 

Deleted: 14
65.17 36.66 22.0  

5.00

F   

F = 191.1 lbf 

(5) Calculate the target value of coastdown force, Fref, based on the applicable dynamometer 

parameters for each speed and inertia setting. 

(6) Compare the mean value of the coastdown force measured for each speed and inertia setting, 

Fact , to the corresponding Fref to determine values for coastdown force error, Ferror, using the 

following equation: 

act ref

error

ref

100 % F F F

F

  

Eq. 1066.270-2

Example:

Fref = 192 lbf 

Fact = 191 lbf 

error

191 192 100 %

192

F   

Ferror = 0.5 % 

(d) Performance evaluation. The coastdown force error determined in paragraph (c) of this 

section may not exceed the following:

(i) For vehicles at or below 20,000 pounds GVWR, calculate Ferrormax from the following 

formula:

Ferrormax (%) = (2.2 lbf/Fref)·100

Eq. 1066.270-3

Example:

Fref = 192 lbf

Ferrormax (%) = (2.2/192)·100 = 1.14%

(ii) For vehicles above 20,000 pounds GVWR, the maximum allowable error, Ferrormax, for all 

speed and inertia settings is ±1.0 % or ±39.2 N, whichever is greater.

(e) If the dynamometer is not able to meet this requirement, diagnose and repair the 

dynamometer before continuing with emission testing. Diagnosis should include performing the 

verifications in §1066.255 and §1066.260.

§1066.280 Dynamometer readiness verification.

(a) Overview. This section describes how to verify that the dynamometer is ready for emission

testing.

(b) Scope and frequency. Perform this verification upon initial installation, within 1 day before 

testing, and after major maintenance.

(c) Procedure. For dynamometers that have an automated process for this verification procedure, 

perform this evaluation by setting the initial speed and final speed and the inertial and road-load 

coefficients as required for the test, using good engineering judgment to ensure that these values 

Deleted: –

Deleted: 7

Deleted: 0

Deleted: 0

Deleted: 0

Deleted: with GVWR 

Deleted: lbs

Deleted: T

Deleted: 6

Deleted: 0

Deleted: (±8.0 lbf)

Deleted: For vehicles with GVWR at or below 

20,000 lbs, calculate Ferrormax

Deleted: is calculated 

Deleted: from the following formula

Deleted: , except that Ferrormax for vehicles with 

GVWR above 14,000 lbs may be up to ±1.0 %

Deleted: :¶

Ferrormax (%) = (2.2 lbf/Fref)·100¶

Eq. 1066.270-3¶

¶

Example:¶

Fref = 192 lbf¶

Ferrormax (%) = (2.2/192)·100 = 1.14%¶

Deleted: 8

Deleted: prior to 

Deleted: s

Deleted: and evaluation 

Deleted: s

Deleted: 3 hours

Deleted: This procedure provides a quality 

measure of the state of a dynamometer's readiness 

for emissions testing. 
properly represent in-use operation. Use the following procedure if your dynamometer does not 

perform this verification with an automated process:

(1) With the dynamometer in coastdown mode, set the dynamometer inertia to the base inertia 

with the road-load coefficient A set to 20 lbf (or a force that results in a coastdown time of less 

than 10 minutes) and coefficients B and C set to 0. Program the dynamometer to coast down for 

one 10 mph interval from 55 mph down to 45 mph. If your dynamometer is not capable of 

performing one discrete coastdown, then coast down with preset 10 mph intervals that include a

55 mph to 45 mph interval.

(2) Perform the coastdown.

(3) Determine the coastdown force and coastdown force error using Eqs. 1066.270-1 and 

1066.270-2.

(d) Performance evaluation. The coastdown force error determined in paragraph (c) of this 

section may not exceed the following:

(1) For vehicles at or below 20,000 pounds GVWR, ±1.0 % or ±9.8 N (±2.2 lbf), whichever is 

greater. 

(2) For vehicles above 20,000 pounds GVWR, ±1.0 % or ±39.2 N (±8.8 lbf), whichever is 

greater.

(e) If the verification results fail to meet the performance criteria in paragraph (d) of this section,

perform the procedure up to two additional times. If the dynamometer is consistently unable to 

meet the performance criteria, diagnose and repair the dynamometer before continuing with

emission testing. Diagnosis should include performing the verifications in §1066.255 and 

§1066.260.

§1066.290 Driver’s aid. 

Use good engineering judgment to provide a driver’s aid that facilitates compliance with the 

requirements of §1066.430. Verify the speed accuracy of the driver’s aid as described in 

§1066.235. 

Deleted: If the result differs from the expected 

value by more than the value given in paragraph (d), 

repeat the steps in this paragraph (c) up to two 

additional times.

Deleted: with GVWR 

Deleted: lbs

Deleted: 0

Deleted: 0

Deleted: with GVWR 

Deleted: lbs

Deleted: 6

Deleted: 0

Deleted: 0

Deleted: not able 

Deleted: this requirement

Deleted: prior to 

Deleted: s

Deleted: and evaluation 

Deleted: 280

Deleted: speed accuracy 
Subpart D—Coastdown 

§1066.301 Overview of coastdown procedures. 

(a) The coastdown procedures described in this subpart are used to determine the load 

coefficients (A, B, and C) for the simulated road-load equation in §1066.210(d)(3). 

(b) The general procedure for performing coastdown tests and calculating load coefficients is 

described in SAE J1263 and SAE J2263 (incorporated by reference in §1066.1010). This 

subpart specifies certain deviations from those procedures for certain applications. 

(c) Use good engineering judgment for all aspects of coastdown testing. For example, minimize 

the effects of grade by performing coastdown testing on reasonably level surfaces and 

determining coefficients based on average values from vehicle operation in opposite directions 

over the course. 

§1066.305 Coastdown procedures for motor vehicles at or below 14,000 pounds GVWR.

For motor vehicles at or below 14,000 pounds GVWR, develop representative road-load 

coefficients to characterize each test vehicle. Calculate road-load coefficients by performing 

coastdowns using the provisions of SAE J1263 and SAE J2263 (incorporated by reference in 

§1066.1010). Perform coastdowns at a starting speed as specified in SAE J2263, or at the 

highest speed from the range of applicable duty cycles. Use the same road-load coefficients for 

all duty cycles. However, if your test conditions are substantially different from the conditions 

represented by your road-load coefficients, such as cold-temperature testing, you may use good 

engineering judgment to develop separate road-load coefficients.

§1066.310 Coastdown procedures for vehicles above 14,000 pounds GVWR. 

This section describes coastdown procedures that are unique to vehicles above 14,000 pounds 

GVWR. These procedures are valid for calculating road-load coefficients for chassis and posttransmission powerpack testing and for calculating drag area (CDA) for use in the GEM

simulation tool under 40 CFR part 1037.

(a) Determine load coefficients by performing a minimum of 16 valid coastdown runs (8 in each 

direction). 

(b) Follow the provisions of Sections 1 through 9 of SAE J1263, and SAE J2263 (incorporated 

by reference in §1066.1010), except as described in this paragraph (b). The terms and variables 

identified in this paragraph (b) have the meaning given in SAE J1263 or J2263 unless specified 

otherwise. 

(1) The test condition specifications of SAE J1263 apply except as follows for wind and road 

conditions: 

(i) We recommend that you do not perform coastdown testing on days for which winds are 

forecast to exceed 6.0 mph. 

(ii) The grade of the test track or road must not be excessive (considering factors such as road 

safety standards and effects on the coastdown results). Road conditions should follow Section 

7.4 of SAE J1263, except that road grade may exceed 0.5%. If road grade is greater than 0.02% 

over the length of the test surface, then the road grade as a function of distance along the length 

of the test surface must be incorporated into the analysis. To calculate the force due to grade use 

Section 11.5 of SAE J2263. 

(2) Operate the vehicle at a top speed above 70 mph, or at its maximum achievable speed if it 

cannot reach 70 mph. If a vehicle is equipped with a vehicle speed limiter that is set for a 

Deleted: 710

Deleted: with GVWR 

Deleted: lbs

Deleted: for chassis testing of motor vehicles with 

GVWR at or below 14,000 pounds GVWR 

Deleted: lbs 

Deleted: heavy-duty

Deleted: with GVWR 

Deleted: lbs

Deleted: heavy-duty 

Deleted: with GVWR 

Deleted: lbs

Deleted: motor vehicles

Deleted: Greenhouse gas Emissions Model (

Deleted: )

Deleted: Note as specified in the standard setting 

parts, this section does not apply for certain heavyduty vehicles, such as those regulated under 40 CFR 

part 86, subpart S.

Deleted: 7

Deleted: You must reach 

Deleted: of greater than 
maximum speed below 70 mph, you must disable the vehicle speed limiter. Start the test at or 

above 70 mph or at the vehicle’s maximum achievable speed if it cannot reach 70 mph. Data 

collection must occur through a minimum speed at or below 15 mph. Data analysis for valid 

coastdown runs must include a maximum speed as described in this paragraph (b)(2) and a 

minimum speed of 15 mph. 

(3) Gather data regarding wind speed and direction, in coordination with time-of-day data, using 

at least one stationary electro-mechanical anemometer and suitable data loggers meeting the 

specifications of SAE J1263, as well as the following additional specifications for the 

anemometer placed adjacent to the test surface: 

(i) Calibrate the equipment by running the zero-wind and zero-angle calibrations within 24 hours

before conducting the coastdown procedures. If the coastdown procedures are not complete 24 

hours after calibrating the equipment, repeat the calibration for another 24 hours of data 

collection.

(ii) Record the location of the anemometer using a GPS measurement device adjacent to the test 

surface (approximately) at the midway distance along the test surface used for coastdowns. 

(iii) Position the anemometer such that it will be at least 2.5 but not more than 3.0 vehicle widths 

from the test vehicle’s centerline as the test vehicle passes the location of that anemometer. 

(iv) Mount the anemometer at a height that is within 6 inches of half the test vehicle’s maximum 

height. 

(v) Place the anemometer at least 50 feet from the nearest tree and at least 25 feet from the 

nearest bush (or equivalent roadside features). 

(vi) The height of the grass surrounding the stationary anemometer may not exceed 10% of the 

anemometer’s mounted height, within a radius equal to the anemometer’s mounted height. 

(4) You may split runs as per Section 9.3.1 of SAE J2263, but we recommend whole runs. If 

you split a run, analyze each portion separately, but count the split runs as one run with respect to 

the minimum number of runs required. 

(5) You may perform consecutive runs in a single direction, followed by consecutive runs in the 

opposite direction, consistent with good engineering judgment. Harmonize starting and stopping 

points to the extent practicable to allow runs to be paired. 

(6) All valid coastdown run times in each direction must be within 2.0 standard deviations of the 

mean of the valid coastdown run times (from 70 mph down to 15 mph) in that direction. 

Eliminate runs outside this range. After eliminating these runs you must have at least eight valid 

runs in each direction. You may use coastdown run times that do not meet these standard 

deviation requirements if we approve it in advance. In your request, describe why the vehicle is 

not able to meet the specified standard deviation requirements and propose an alternative set of 

requirements.

(7) Analyze data for chassis and post-transmission powerpack testing or for use in the GEM 

simulation tool as follows:

(i) Follow the procedures specified in Section 10 of SAE J1263 or Section 11 of SAE J2263 to 

calculate coefficients for chassis and post-transmission powerpack testing.

(ii) Determine drag area, CDA, as follows instead of using the procedure specified in Section 10 

of SAE J1263: 

(A) Measure vehicle speed at fixed intervals over the coastdown run (generally at 10 Hz), 

including speeds at or above 15 mph and at or below 70 mph. Establish the height or altitude 

corresponding to each interval as described in SAE J2263 if you need to incorporate the effects 

of road grade. 

Deleted: such that data collection of the coastdown 

can start at or above 70 mph. 

Deleted: of 70 mph 

Deleted: Run 

Deleted: data collection

Deleted: ¶

(ii) The anemometer must have had its outputs 

recorded at a wind speed of 0.0 mph within 24 hours 

before each coastdown test in which it is used.

Deleted: i

Deleted: iv

Deleted: i

Deleted: i

Deleted: For the GEM simulation tool, d

Deleted: D

Deleted: , Section 10

Deleted: i
(B) Calculate the vehicle’s effective mass, Me, in kg by adding 56.7 kg to the vehicle mass for 

each tire making road contact. This accounts for the rotational inertia of the wheels and tires. 

(C) Calculate the road-load force for each measurement interval, Fi, for values of i ≥ 1 using the 

following equation: 

i i1

i e

v v F M

t

    

Eq. 1066.310-1 

Where: 

Me = the vehicle’s effective mass, expressed to the nearest 0.1 kg. 

v = vehicle speed at the beginning and end of the measurement interval. 

Δt = elapsed time over the measurement interval, in seconds. 

(D) Plot the data from all the coastdown runs on a single plot of Fi vs. vi

2

 to determine the slope 

correlation, D, based on the following equation: 

2

ie m i

h F M g A Dv s

    



Eq. 1066.310-2 

Where: 

g = gravitational acceleration = 9.81 m/s2

. 

Δh = change in height or altitude over the measurement interval, in m. Assume Δh = 0 if you are 

not correcting for grade. 

Δs = distance the vehicle travels down the road during the measurement interval, in m. 

Am = the calculated value of the y-intercept based on the curve-fit. 

(E) Calculate drag area, CDA, in m2

 using the following equation: 

adj

D

2 D

C A



 

Eq. 1066.310-3 

Where: 

ρ = air density at reference conditions = 1.17 kg/m3

. 

adj

B

98.21

293

T D D

p

             

Eq. 1066.310-4 

T = average ambient temperature during testing, in K. 

B p = average ambient pressuring during the test, in kPa. 

(8) Determine the A, B, and C coefficients identified in §1066.210 as follows:

(i) For chassis and post-transmission powerpack testing, follow the procedures specified in 

Section 10 of SAE J1263 or Section 12 of SAE J2263.

(ii) For the GEM simulation tool, use the following values:

A = Am

B = 0 

C = Dadj

Deleted: ii

Deleted: iii

Deleted: Vehicle 

Deleted: Let v0 = 0 m/s.

Deleted: Elapsed 

Deleted: iv

Deleted: Gravitational 

Deleted: Change 

Deleted: Distance 

Deleted: v

Deleted: Air 

Deleted: Average 

Deleted: Average 
§1066.320 Dynamometer road-load setting.

Determine dynamometer road-load settings for chassis testing by following SAE J2264

(incorporated by reference in §1066.1010).
Subpart E— Preparing Vehicles and Running an Exhaust Emission Test

§1066.401 Overview. 

(a) Use the procedures detailed in this subpart to measure vehicle emissions over a specified 

drive schedule. Different procedures may apply for criteria pollutants and greenhouse gas 

emissions as described in subpart I of this part or the standard-setting part. This subpart 

describes how to: 

(1) Determine road-load power, test weight, and inertia class. 

(2) Prepare the vehicle, equipment, and measurement instruments for an emission test. 

(3) Perform pre-test procedures to verify proper operation of certain equipment and analyzers 

and to prepare them for testing. 

(4) Record pre-test data. 

(5) Sample emissions. 

(6) Record post-test data. 

(7) Perform post-test procedures to verify proper operation of certain equipment and analyzers. 

(8) Weigh PM samples. 

(b) The overall test consists of prescribed sequences of fueling, parking, and driving at specified 

test conditions. An exhaust emission test generally consists of measuring emissions and other 

parameters while a vehicle follows the drive schedules specified in the standard-setting part. 

There are two general types of test cycles: 

(1) Transient cycles. Transient test cycles are typically specified in the standard-setting part as a 

second-by-second sequence of vehicle speed commands. Operate a vehicle over a transient cycle 

such that the speed follows the target values. Proportionally sample emissions and other 

parameters and use the calculations in 40 CFR part 1065, subpart G, or subpart G of this part to 

calculate emissions. The standard-setting part may specify three types of transient testing based 

on the approach to starting the measurement, as follows: 

(i) A cold-start transient cycle where you start to measure emissions just before starting an 

engine that has not been warmed up. 

(ii) A hot-start transient cycle where you start to measure emissions just before starting a 

warmed-up engine. 

(iii) A hot running transient cycle where you start to measure emissions after an engine is started, 

warmed up, and running. 

(2) Cruise cycles. Cruise test cycles are typically specified in the standard-setting part as a 

discrete operating point that has a single speed command. 

(i) Start a cruise cycle as a hot running test, where you start to measure emissions after the 

engine is started and warmed up and the vehicle is running at the target test speed. 

(ii) Sample emissions and other parameters for the cruise cycle in the same manner as a transient 

cycle, with the exception that the reference speed value is constant. Record instantaneous and 

mean speed values over the cycle. 

§1066.407 Vehicle preparation and preconditioning. 

Prepare the vehicle for testing, including measurement of evaporative and refueling emissions, as 

described in the standard-setting part. 

§1066.410 Dynamometer test procedure. 

Deleted: Preparation 

Deleted: 86

Deleted: B

Deleted: 40 CFR part 1065,

Deleted: ,

Deleted: This section describes steps to take before 

measuring exhaust emissions for those vehicles that 

are subject to evaporative or refueling emission tests 

as specified in the standard setting part. Other 

preliminary procedures may apply as specified in the 

standard-setting part.¶

(a) 

Deleted: 40 CFR 86.131-00

Deleted: (b) If testing will include measurement of 

refueling emissions, perform the vehicle 

preconditioning steps as described in 40 CFR 

86.153-98the standard setting part. Otherwise, 

perform the vehicle preconditioning steps as 

described in 40 CFR 86.132-00.
(a) Dynamometer testing may consist of multiple drive cycles with both cold-start and hot-start 

portions, including prescribed soak times before each test interval. The standard-setting part 

identifies the driving schedules and the associated sample intervals, soak periods, engine startup

and shutdown procedures, and operation of accessories, as applicable. Not every test interval

includes all these elements.

(b) Place the vehicle onto the dynamometer without starting the engine (cold start test cycles 

only) or drive the vehicle onto dynamometer and position a fan that appropriately directs cooling 

air to the vehicle during dynamometer operation as described in this paragraph (b). This 

generally requires squarely positioning the fan in front of the vehicle and directing the airflow to 

the vehicle’s radiator. Use good engineering judgment to design and configure fans to cool the 

test vehicle in a way that properly simulates in-use operation.

(1) For vehicles at or below 14,000 pounds GVWR, use the following cooling fan configurations

as allowed under Table 1 of this section: 

(i) Use a fixed-speed fan to appropriately direct cooling air to the vehicle with the engine 

compartment cover open. The fan capacity may not exceed 2.50 m3

/s and the fan should be 

placed nominally within the range of (0 to 30) cm from the front of the vehicle. If you 

determine that additional cooling is needed to properly represent in-use operation, use good 

engineering judgment to increase the fan’s capacity or use additional fans, subject to our 

approval. When testing under this option, the engine compartment cover must be open.

(ii) Use a fixed-speed fan to direct cooling air to the vehicle with the engine compartment cover 

open. The fan capacity may not exceed 7.10 m3/s and the fan should be placed nominally within 

the range of (0 to 60) cm from the front of the vehicle. If you determine that additional cooling

is needed to properly represent in-use operation, use good engineering judgment to increase the 

fan’s capacity or use additional fans, subject to our approval. When testing under this option, the 

engine compartment cover must be open.

(iii) Use a road-speed modulated fan system that achieves a linear speed of cooling air at the 

blower outlet that is within ±3.0 mph (±1.3 m/s) of the corresponding roll speed when vehicle 

speeds are between 5 and 30 mph (2.2 to 13.4 m/s), and within ±6.5 mph (±2.9 m/s) of the 

corresponding roll speed at higher vehicle speeds. You may limit your fan maximum linear 

speed to 70 mph for roll speeds in excess of 70 mph. We recommend that the cooling fan have a 

minimum opening of 0.2 m2 and a minimum width of 0.8 m. The discharge nozzle shall be 

placed nominally within the range of (0 to 90) cm from the front of the vehicle to provide 

representative cooling. When testing under this option, the engine compartment cover must be 

closed.

(iv) Use a road-speed modulated fan system with a minimum air flow nozzle discharge area that 

is equal to or exceeds the vehicle frontal inlet area. The optimum discharge area is 1.7 m2 (1.3 m

× 1.3 m), however, other sizes can be used. The discharge nozzle should be placed nominally

within the range of (60 to 90) cm from the front of the vehicle and 0 to 16 cm from the floor of 

the test cell. When testing under this option, the engine compartment cover must be closed.

(A) Air flow volumes must be proportional to vehicle speed. With the above optimum discharge 

size, the fan volume would vary from 0 cubic feet/minute (cfm) at 0 mph to approximately 

95,000 cfm at 60 mph. If this fan is also the only source of cell air circulation or if fan 

operational mechanics make the 0 mph air flow requirement impractical, air flow of 2 mph or 

less will be allowed at 0 mph vehicle speed.

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: See the standard-setting part for test 

cycles and soak times for the appropriate vehicle 

category. A test phase consists of engine startup 

(with accessories operated according to the standardsetting part), operation over the drive cycle, and 

engine shutdown.

Deleted: During dynamometer operation, p

Deleted: cooling 

Deleted: within 30 centimeters of the

Deleted: with GVWR 

Deleted: lbs

Deleted: you may 

Deleted: either of 

Deleted: nominally within

Deleted: 1

Deleted: of

Deleted: appropriately 

Deleted: nominally within 61 

Deleted: approximately

Deleted: 3

Deleted: of

Deleted: The fan must provide no cooling air for 

vehicle speeds below 5 mph, unless we approve your 

request to provide cooling during low-speed 

operation based on a demonstration that this is 

appropriate to simulate cooling for in-use vehicles.

Deleted: nominally within

Deleted: 61

Deleted: of

Deleted: 8

Deleted: 4.25

Deleted: 4.25

Deleted: 2
(B) The fan air flow velocity vector perpendicular to the axial flow velocity vector shall be less 

than 10 % of the mean velocity measured at fan speeds corresponding to vehicle speeds of 20 

and 40 mph.

(C) The uniformity of fan axial flow tolerance is 20 % of the fan speed corresponding to vehicle 

speeds of 20 and 40 mph. Measure the fan axial air flow velocity two feet from the nozzle outlet 

at each point of the discharge area grid. 

(1) For fans with rectangular outlets, divide the fan outlet into 9 equal sections (dividing both the

horizontal and vertical sides of the fan outlet into 3 equal parts) as described in Figure 1 of 

§1066.410. As denoted by the “+” in the Figure, measure flow from the center of each section; 

however do not measure the flow from the center section.

Figure 1 of §1066.410—Rectangular fan outlet grid.

(2) For fans with circular outlets, divide the fan outlet into 8 equal sections (divide using vertical, 

horizontal, and 45° lines) as described in Figure 2 of §1066.410. As denoted by the “+” in the 

Figure, measure flow on the radial center line of each arc (at 22.5°) at a radius of two thirds of 

the total.

 Figure 2 of §1066.410—Circular fan outlet grid.

(D) The instrument used to verify the air velocity must have an accuracy of 2 % of the measured 

air flow speed.

Table 1 of §1066.410–Test cell vehicle cooling fan requirements.

Test cycle Allowable cooling 

fan configurations

FTP and LA-92 1066.410(b)(1)(i),

1066.410(b)(1)(iii)

Deleted: percent

Comment [CAL1]: Alan, please review “C”. 

Deleted: Fan axial air flow velocity is measured 

two feet from nozzle outlet at each point of a one 

foot grid over the entire discharge area. 

Deleted: percent

Deleted: s

Deleted: percent

Deleted: , AC idle,
US06 1066.410(b)(1)(ii), 

1066.410(b)(1)(iii)

SC03 and AC17 1066.410(b)(1)(iv)

HFET 1066.410(b)(1)(i), 

1066.410(b)(1)(iii)

(2) For vehicles above 14,000 pounds GVWR, use a road-speed modulated fan system that 

achieves a linear speed of cooling air at the blower outlet that is within ±3.0 mph (±1.3 m/s) of 

the corresponding roll speed when vehicle speeds are between 5 and 30 mph (2.2 to 13.4 m/s), 

and within ±10 mph (±4.5 m/s) of the corresponding roll speed at higher vehicle speeds. For 

vehicles with GVWR above 19,500 lbs, we recommend that the cooling fan have a minimum 

opening of 2.75 m2, a minimum flow rate of 3,600 m3/min at 50 mph, and that it maintain a 

minimum speed profile across the duct, in the free stream flow, of ±15 % of the target flow rate. 

The discharge nozzle shall be placed approximately 30 to 60 cm of the front of the vehicle to 

provide representative cooling. When testing under this option, the engine compartment cover 

must be closed.

(3) If the cooling specifications in this paragraph (b) are impractical for special vehicle designs, 

such as vehicles with rear-mounted engines, you may arrange for an alternative fan configuration 

that allows for proper simulation of vehicle cooling during in-use operation, subject to our 

approval. 

(c) Record the vehicle’s speed trace based on the time and speed data from the dynamometer. 

Record speed to at least the nearest 0.01 mph and time to at least the nearest 0.1 s. 

(d) You may perform practice runs for operating the vehicle and the dynamometer controls to 

meet the driving tolerances specified in §1066.430 or adjust the emission sampling equipment. 

Verify that the accelerator pedal allows for enough control to closely follow the prescribed 

driving schedule. We recommend that you verify your ability to meet the minimum dilution 

factor requirements of §1066.110(b)(2)(iii)(B) during these practice runs.

(e) Inflate tires on drive wheels according to the vehicle manufacturer’s specifications. The tire 

pressure for drive wheels must be the same for dynamometer operation and for dynamometer

coastdown procedures used for determining road-load coefficients. Report these tire pressure 

values with the test results. 

(f) Tie down or load the test vehicle as needed to provide a normal force at the tire and 

dynamometer roll interface to prevent wheel slip. For vehicles above 14,000 pounds GVWR,

report this force with the test results.

(g) For vehicles which provide four-wheel drive or all-wheel drive operation, utilize the vehicle’s 

normal (default) mode of operation. This may involve testing four-wheel drive or all-wheel 

drive on a dynamometer with a separate dynamometer roll for each drive axle. Alternatively, 

two drive axles may use a single roll, as described in §1066.210(d)(1). You may also test the 

vehicle on a single roll by deactivating the second set of drive wheels, but only if this mode of 

operation does not decrease emissions or energy consumption relative to normal in-use operation. 

We may test such vehicles in multiple-wheel or all-wheel mode on one or more rolls to confirm 

that the alternate dynamometer procedures did not decrease emissions.

(h) Determine test weight as follows:

(1) For vehicles at or below 14,000 pounds GVWR, determine ETW as described in §1066.810. 

Set dynamometer vehicle inertia, I, based on dynamometer type, as follows: 

(i) For two-wheel drive dynamometers, set I = ETW.

(ii) For four-wheel drive dynamometers, set I = 0.985·ETW.

Deleted: , AC1, AC2,

Deleted: with GVWR 

Deleted: lbs

Deleted: The fan must provide no cooling air for 

vehicle speeds below 5 mph, unless we approve your 

request to provide cooling during low-speed 

operation based on a demonstration that this is 

appropriate to simulate the cooling experienced by 

in-use vehicles. We 

Deleted: nominally within 61

Deleted: 0.01 m/s or 

Deleted: to 

Deleted: You may not measure emissions during a 

practice run.

Deleted: the drive wheel 

Deleted: drive wheels’ 

Deleted: For vehicles with GVWR above 14,000 

lbs, you must use a vehicle pull down mechanism 

that allows simulation of the actual 

Deleted: s

Deleted: th

Deleted: would see if a loaded vehicle were 

actually being tested. Use of this mechanism will 

ensure that wheel slip does not occur when trying to 

accelerate the loaded vehicle.

Deleted: with GVWR 

Deleted: lbs

Deleted: R

Deleted: Use good engineering judgment when 

testing

Deleted: in four-wheel drive or all-wheel drive 

mode

Deleted: This may also involve operation on a

Deleted: , which may require disengaging 

Deleted: either with a switch available to the 

driver or by some other means; however, operating 

such a vehicle on a single roll may occur 

Deleted: Alternatively, for heavy-duty motor 

vehicles, up to two drive axles may use a single drive 

roll, as described in §1066.210(d)(2).

Deleted: with a GVWR 

Deleted: lbs

Deleted: 40 CFR part 86.129-00

Deleted: 1.015·
(2) For vehicles above 14,000 pounds GVWR, determine the vehicle’s effective mass as 

described in 1066.310.

(i) Warm up the dynamometer as recommended by the dynamometer manufacturer. 

(j) Following the test, determine the actual driving distance by counting the number of 

dynamometer roll or shaft revolutions, or by integrating speed over the course of testing from a 

high-resolution encoder system. 

§1066.420 Vehicle operation.

This section describes how to test a conventionally configured vehicle (vehicles with 

transmission shifters, foot pedal accelerators, etc). You may ask us to modify these procedures 

for vehicles that do not have these control features. 

(a) Start the vehicle as follows:

(1) At the beginning of the test cycle, start the vehicle according to the procedure described in 

the owners manual. In the case of hybrid vehicles, this would generally involve activating 

vehicle systems such that the engine will start when the vehicle’s control algorithms determine 

that the engine should provide power instead of or in addition to power from the rechargeable 

energy storage system (RESS). Unless we specify otherwise, engine starting throughout this part 

generally refers to this step of activating the system on hybrid vehicles, whether or not that 

causes the engine to start running.

(2) Place the transmission in gear as described by the test cycle in the standard-setting part. 

During idle operation, you may apply the brakes if necessary to keep the drive wheels from 

turning.

(b) If the vehicle does not start after your recommended maximum cranking time, wait and 

restart cranking according to your recommended practice. If you don’t recommend such a 

cranking procedure, stop cranking after 10 seconds, wait for 10 seconds, then start cranking 

again for up to 10 seconds. You may repeat this for up to three start attempts. If the vehicle 

does not start after three attempts, you must determine and record the reason for failure to start. 

Shut off sampling systems and either turn the CVS off or disconnect the exhaust tube from the 

tailpipe during the diagnostic period to prevent flow through the exhaust system. Reschedule the 

vehicle for testing. This may require performing vehicle preparation and preconditioning if the 

testing needs to be rerun from a cold start. If failure to start occurs during a hot start test, you 

may reschedule the hot start test without repeating the cold start test, as long as you bring the 

vehicle to a hot start condition before starting the hot start test.

(c) Repeat the recommended starting procedure if the engine has a false start (i.e., an incomplete 

start).

(d) Take the following steps if the engine stalls:

(1) If the engine stalls during an idle period, restart the engine immediately and continue the test. 

If you cannot restart the engine soon enough to allow the vehicle to follow the next acceleration, 

stop the driving schedule indicator and reactivate it when the vehicle restarts.

(2) Void the test if the vehicle stalls during vehicle operation. If this happens, remove the 

vehicle from the dynamometer, take corrective action, and reschedule the vehicle for testing. 

Record the reason for the malfunction (if determined) and any corrective action. See the 

standard-setting part for instructions about reporting these malfunctions. 

(e) Operate vehicles during testing as follows:

Deleted: with a GVWR 

Deleted: lbs

Deleted: h

Deleted: i

Deleted: you 

Deleted: your 

Deleted: ,

Deleted: “

Deleted: ”
(1) Where we do not give specific instructions, operate the vehicle according to the 

recommendations in the owners manual, unless those recommendations are unrepresentative of 

what may reasonably be expected for in-use operation.

(2) If vehicles have features that preclude dynamometer testing, you may modify these features 

as necessary to allow testing, consistent with good engineering judgment, as long as it does not 

affect your ability to show that your vehicles comply with standards. Send us written 

notification describing these changes along with supporting rationale.

(3) Operate vehicles during idle as follows:

(i) For vehicles with automatic transmission, operate at idle with the transmission in “Drive” 

with the wheels braked, except that you may shift to “Neutral” for the first idle period and for 

any idle period longer than one minute. If you put the vehicle in “Neutral” during an idle, you 

must shift the vehicle into “Drive” with the wheels braked at least 5 seconds before the end of 

the idle period. Note that this does not preclude vehicle designs involving engine operation with 

stop-start functions where the engine stops when the brake is applied below a certain threshold 

speed and restarts upon release of the brake.

(ii) For vehicles with manual transmission, operate at idle with the transmission in gear with the 

clutch disengaged, except that you may shift to “Neutral” with the clutch engaged for the first 

idle period and for any idle period longer than one minute. If you put the vehicle in “Neutral” 

during idle, you must shift to first gear with the clutch disengaged at least 5 seconds before the 

end of the idle period. Note that this does not preclude vehicle designs involving engine 

operation with stop-start functions where the engine stops when the clutch is disengaged below a 

certain threshold speed and restarts upon reengagement of the clutch.

(4) Use the appropriate accelerator pedal to achieve the speed versus time relationship prescribed 

by the driving schedule. Avoid smoothing speed variations and excessive accelerator pedal 

perturbations.

(5) Operate the vehicle smoothly, following representative shift speeds and procedures. For 

manual transmissions, the operator shall release the accelerator pedal during each shift and 

accomplish the shift with minimum time. If the vehicle cannot accelerate at the specified rate, 

operate it at maximum available power until the vehicle speed reaches the value prescribed for 

that time in the driving schedule.

(6) Decelerate as follows:

(i) For vehicles with automatic transmission, use the brakes or accelerator pedal as necessary, 

without manually changing gears, to maintain the desired speed.

(ii) For vehicles with manual transmission, shift gears in a way that represents reasonable shift 

patterns for in-use operation, considering vehicle speed, engine speed, and any other relevant

variables. Disengage the clutch when the speed drops below 15 mph, when engine roughness is 

evident, or when good engineering judgment indicates the engine is likely to stall. 

Manufacturers may recommend shift guidance in the owners manual that differs from the shift 

schedule during testing as long as both shift schedules are included in the application for 

certification. In this case, we may use the shift schedule based on the shift pattern described in 

the owners manual.

§1066.425 Test preparation. 

(a) Follow the procedures for PM sample preconditioning and tare weighing as described in 40 

CFR 1065.590 if you need to measure PM emissions.

Deleted: your 

Deleted: Operate the vehicle with the 

Deleted: movement necessary 

Deleted: 6.7 m/s (

Deleted: )

Deleted: engine stalling is imminent

Deleted: You 

Deleted: your

Deleted: your

Deleted: you include 

Deleted: your

Deleted: you 

Deleted: your

Deleted: 420 

Deleted: Pre-test verification procedures and 

pre-test data collection

Deleted: your engine must comply with a PM 

standard
(b) For vehicles above 14,000 pounds GVWR with compression-ignition engines, verify the 

amount of nonmethane hydrocarbon contamination as described in 40 CFR 1065.520(g).

(c) Unless the standard-setting part specifies different tolerances, verify at some point before the 

test that ambient conditions are within the tolerances specified in this paragraph (c). For 

purposes of this paragraph (c), “before the test” means any time from a point just prior to engine 

starting (excluding engine restarts) to the point at which emission sampling begins. 

(1) Ambient temperature must be (20 to 30) °C. See §1066.430(i) for circumstances under 

which ambient temperatures must remain within this range during the test. 

(2) Dilution air conditions must meet the specifications in §1066.110(b)(2). We recommend 

verifying dilution air conditions just before starting each test interval. 

(d) Control test cell ambient air humidity as follows:

(1) For vehicles at or below 14,000 pounds GVWR, follow the humidity requirements in Table 1 

of this section, unless the standard-setting part specifies otherwise. When complying with 

humidity requirements in the table, where no tolerance is specified, use good engineering 

judgment to maintain the humidity level near the specified value within the limitations of your 

test facility.

(2) For vehicles above 14,000 pounds GVWR, you may test vehicles at any humidity.

Table 1 of §1066.425–Test cell humidity requirements.

Test cycle

Humidity 

requirement 

(grains H2O/lb 

of dry air)

Tolerance (grains 

H2O/lb of dry air)

AC17 69 ± 5 average, 

± 10 instantaneous

FTP1 and LA-92 50

HFET 50

SC03 100 ± 5

US06 50

1

FTP humidity requirement does not apply for cold (-7°C), 

intermediate (10 °C), and hot (35 °C) temperature testing.

(e) You may perform a final calibration of proportional-flow control systems, which may include 

performing practice runs. 

(f) You may perform the following procedure to precondition sampling systems: 

(1) Operate the vehicle over the test cycle. 

(2) Operate any dilution systems at their expected flow rates. Prevent aqueous condensation in 

the dilution systems as described in 40 CFR 1065.140(c)(6), taking into account allowances 

given in §1066.110(b)(2)(iv). 

(3) Operate any PM sampling systems at their expected flow rates. 

(4) Sample PM using any sample media. You may change sample media during preconditioning. 

You must discard preconditioning samples without weighing them. 

(5) You may purge any gaseous sampling systems during preconditioning. 

(6) You may conduct calibrations or verifications on any idle equipment or analyzers during 

preconditioning.

(g) Take the following steps before emission sampling begins:

Deleted: and GVWR above 14,000 lbs

Deleted: b

Deleted: b

Deleted: b

Deleted: m

Deleted: (2) Atmospheric pressure must be 

(80.000 to 103.325) kPa. You are not required to 

verify atmospheric pressure prior to a hot-start test 

interval for testing that also includes a cold start.¶

Deleted: 3

Deleted: 40 CFR 

Deleted: 5

Deleted: 140

Deleted: , except in cases where you preheat your 

CVS before a cold-start test

Deleted: phase

Deleted: c

Deleted: with GVWR 

Deleted: lbs

Deleted: see the standard-setting part or

Deleted: §1066.425 

Deleted: for humidity requirements

Deleted: with GVWR 

Deleted: lbs

Deleted: Y

Deleted: intake-air 

Deleted: nominal 

Deleted: , AC1, AC2

Deleted: d

Deleted: e

Deleted: for at least 10 min 
(1) For batch sampling, connect clean storage media, such as evacuated bags or tare-weighed 

filters.

(2) Start all measurement instruments according to the instrument manufacturer’s instructions 

and using good engineering judgment.

(3) Start dilution systems, sample pumps, and the data-collection system.

(4) Pre-heat or pre-cool heat exchangers in the sampling system to within their operating 

temperature tolerances for a test.

(5) Allow heated or cooled components such as sample lines, filters, chillers, and pumps to 

stabilize at their operating temperatures.

(6) Adjust the sample flow rates to desired levels using bypass flow, if desired. 

(7) Zero or re-zero any electronic integrating devices before the start of any test interval.

(8) Select gas analyzer ranges. You may not switch the gain of an analyzer’s analog operational 

amplifier(s) during a test. However, you may switch (automatically or manually) gas analyzer 

ranges during a test if such switching changes only the range over which the digital resolution of 

the instrument is applied.

(9) Zero and span all continuous gas analyzers using gases that meet the specifications of 40 

CFR 1065.750. For FID analyzers, you may account for the carbon number of your span gas 

either during the calibration process or when calculating your final emission value. For example, 

if you use a C3H8 span gas of concentration 200 ppm (mol/mol), you may span the FID to 

respond with a value of 600 ppm (mol/mol) of carbon or 200 ppm of propane. However, if 

your FID response is equivalent to propane, include a factor of three to make the final calculated 

hydrocarbon mass consistent with a molar mass of 13.875389. When utilizing an NMC-FID, 

span the FID analyzer consistent with the determination of their respective response factors, RF, 

and penetration fractions, PF, according to 40 CFR 1065.365.

(10) We recommend that you verify gas analyzer responses after zeroing and spanning by 

sampling a calibration gas that has a concentration near one-half of the span gas concentration. 

Based on the results and good engineering judgment, you may decide whether or not to re-zero, 

re-span, or re-calibrate a gas analyzer before starting a test.

(11) If you correct for dilution air background concentrations of associated engine exhaust 

constituents, start sampling and recording background concentrations at the same time you start 

sampling exhaust gases.

(12) Turn on cooling fans immediately before starting the test.

(h) Proceed with the test sequence described in §1066.430. 

§1066.430 Performing emission tests. 

(a) See the standard-setting part for drive schedules. These are defined by a smooth trace drawn 

through the specified speed vs. time sequence. 

(b) The driver must attempt to follow the target schedule as closely as possible, consistent with 

the specifications in paragraph (b) of this section. Instantaneous speeds must stay within the 

following tolerances: 

(1) The upper limit is 2.0 mph higher than the highest point on the trace within 1.0 s of the given 

point in time. 

(2) The lower limit is 2.0 mph lower than the lowest point on the trace within 1.0 s of the given 

time. 

(3) The same limits apply for vehicle preconditioning and warm-up, except that the upper and 

lower limits for speed values are ±4.0 mph. 

Deleted: phase

Deleted: Y

Deleted: automatically or manually 

Deleted: only 

Deleted: is performed by 

Deleted: ing

Deleted: During a test you may not switch the 

gains of an analyzer’s analog operational 

amplifier(s).

Deleted: If you do not span your FID analyzers 

and measure THC on a carbon number basis of one 

(C1) , make sure that you account for the carbon 

number of your span gas when reporting your final 

emission value.

Deleted: 7

Deleted: (f) Verify the amount of nonmethane 

hydrocarbon (or equivalent) contamination in the 

exhaust and background HC sampling systems 

within 8 hours before the start of the first test drive 

cycle for each individual vehicle tested as described 

in 40 CFR 1065.520(g).¶

¶

§1066.425 Engine starting and restarting.¶

(a) Start the vehicle’s engine as follows:¶

(1) At the beginning of the test cycle, start the engine 

according to the procedure you describe in your 

owners manual. In the case of hybrid vehicles, this 

would generally involve activating vehicle systems 

such that the engine will start when the vehicle’s 

control algorithms determine that the engine should 

provide power instead of or in addition to power 

from the rechargeable energy storage system (RESS). 

Unless we specify otherwise, engine starting 

throughout this part generally refers to this step of 

activating the system on hybrid vehicles, whether or 

not that causes the engine to start running.¶

(2) Place the transmission in gear as described by the 

test cycle in the standard-setting part. During idle 

operation, you may apply the brakes if necessary to 

keep the drive wheels from turning.¶

(b) If the vehicle does not start after your 

recommended maximum cranking time, wait and 

restart cranking according to your recommended 

practice. If you don’t recommend such a cranking 

procedure, stop cranking after 10 seconds, wait for 

10 seconds, then start cranking gain for up to 10 

seconds. You may repeat this for up to three start ... [1]

Deleted: The overall test consists of prescribed 

sequences of fueling, parking, and driving at 

specified test conditions.¶ ... [2]

Deleted: d

Deleted: e

Deleted: 1.0 m/s (

Deleted: )

Deleted: 1.0 m/s (

Deleted: )

Deleted: ±2.0 m/s (

Deleted: )
(4) Void the test if you do not maintain speed values as specified in this paragraph (b). Speed 

variations (such as may occur during gear changes or braking spikes) may occur as follows, 

provided that such variations are clearly documented, including the time and speed values and 

the reason for the deviation: 

(i) Speed variations greater than the specified limits are acceptable for up to 2.0 seconds on any 

occasion. 

(ii) For vehicles that are not able to maintain acceleration as specified in §1066.420(e)(5), do not 

count the insufficient acceleration as being outside the specified limits.

(5) We may approve an alternate test cycle and cycle-validation criteria for vehicles that do not

have enough power to follow the specified driving trace. The alternate driving specifications 

must be based on making best efforts to maintain acceleration and speed to follow the specified 

test cycle. We must approve these alternate driving specifications before you perform this 

testing.

(c) Figure 1 and Figure 2 of this section show the range of acceptable speed tolerances for typical 

points during testing. Figure 1 of this section is typical of portions of the speed curve that are 

increasing or decreasing throughout the 2-second time interval. Figure 2 of this section is typical 

of portions of the speed curve that include a maximum or minimum value. 

Deleted: e

Deleted: (4)

Deleted: paragraph 

Deleted: c

Deleted: of this section

Deleted: f
Figure 1 of §1066.430—Example of the allowable ranges for the driver’s trace. 

Figure 2 of §1066.430—Example of the allowable ranges for the driver’s trace. 

1.0 s

Time

S

peed

Allowable

Range

2.0 mph

2.0 mph

1.0 s

1.0 s

Time

S

peed

Allowable

Range

2.0 mph

2.0 mph

1.0 s
(d) Start testing as follows: 

(1) If a vehicle is already running and warmed up, and starting is not part of the test cycle, 

operate the vehicle as follows: 

(i) For transient test cycles, control vehicle speeds to follow a drive schedule consisting of a 

series of idles, accelerations, cruises, and decelerations. 

(ii) For cruise test cycles, control the vehicle operation to match the speed of the first interval of 

the test cycle. Follow the instructions in the standard-setting part to determine how long to 

stabilize the vehicle during each interval, how long to sample emissions at each interval, and 

how to transition between intervals. 

(2) If engine starting is part of the test cycle, initiate data logging, sampling of exhaust gases, and 

integrating measured values before starting the engine. Initiate the driver’s trace when the 

engine starts.

(e) Perform the following at the end of each test interval, except as specified in subpart I of this 

part:

(i) Shut down the vehicle if it is part of the test cycle or if testing is complete.

(ii) Continue to operate all sampling and dilution systems to allow the response times to elapse. 

Then stop all sampling and recording, including background sampling. Finally, stop any 

integrating devices and indicate the end of the duty cycle in the recorded data. 

(f) If testing involves engine shutdown followed by another test interval, start a timer for the 

vehicle soak when the engine shuts down. Turn off cooling fans, close the vehicle hood (if 

applicable), and turn off the CVS or disconnect the exhaust tube from the tailpipe(s) of the 

vehicle unless otherwise instructed in the standard-setting part. If testing is complete, disconnect 

the exhaust tube from the vehicle tailpipe(s) and drive the vehicle from dynamometer.

(g) Take the following steps after emission sampling is complete: 

(1) For any proportional batch sample, such as a bag sample or PM sample, verify that 

proportional sampling was maintained according to 40 CFR 1065.545. Void any samples that 

did not maintain proportional sampling according to those specifications.

(2) Place any used PM samples into covered or sealed containers and return them to the PMstabilization environment. Follow the PM sample post-conditioning and total weighing 

procedures in 40 CFR 1065.595. 

(3) As soon as practical after the interval or test cycle is complete, or optionally during the soak 

period if practical, perform the following:

(i) Begin drift check for all continuous gas analyzers as described in paragraph (g)(6) of this 

section and zero and span all batch gas analyzers as soon as practical prior to any batch sample 

analysis. You may perform this batch analyzer zero and span prior to the end of the test cycle or 

interval. 

(ii) Analyze any conventional gaseous batch samples (HC, CO, NOx, and CO2) no later than 30 

minutes after an interval or test cycle is complete, or during the soak period if practical. Analyze 

background samples no later than 60 minutes after the test cycle is complete.

(iii) Analyze nonconventional gaseous batch samples (including background), such as NMHCE, 

N2O, or NMOG sampling with ethanol, as soon as practicable using good engineering judgment.

(4) Range validation. If an analyzer operated above 100 % of its range at any time during the 

test, perform the following steps:

Deleted: g

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: h

Deleted: At 

Deleted: interval

Deleted: phase

Deleted: , 

Deleted: continue 

Deleted: the recording of 

Deleted: samples

Deleted: (i) Shut down the vehicle if it is part of 

the test cycle or if testing is complete.¶

Deleted: j

Deleted: phase

Deleted: k

Deleted: ¶

Deleted: phase

Deleted: Drift 

Deleted: phase

Deleted: .

Deleted: no later than 30 minutes after the test 

cycle is complete, or during the soak period if 

practical

Deleted: test 

Deleted: phase

Deleted: Analyze nonconventional gaseous batch 

samples, such as NMHCEsampling with ethanol, as 

soon as practicable using good engineering judgment.

Deleted: Analyze background samples no later 

than 60 minutes after the test cycle is complete.
(i) For batch sampling, re-analyze the sample using the lowest analyzer range that results in a 

maximum instrument response below 100 %. Report the result from the lowest range from 

which the analyzer operates below 100 % of its range.

(ii) For continuous sampling, repeat the entire test using the next higher analyzer range. If the 

analyzer again operates above 100 % of its range, repeat the test using the next higher range. 

Continue to repeat the test until the analyzer consistently operates at less than 100 % of its range.

(5) After quantifying exhaust gases, verify drift as follows: 

(i) For batch and continuous gas analyzers, record the mean analyzer value after stabilizing a 

zero gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, 

plus any additional time to account for analyzer response. 

(ii) Record the mean analyzer value after stabilizing the span gas to the analyzer. Stabilization 

may include time to purge the analyzer of any sample gas, plus any additional time to account for 

analyzer response. 

(iii) Use these data to validate that analyzer drift does not exceed 2.0 % of the analyzer full scale. 

(h) [Reserved] 

(i) Measure and record ambient pressure. Measure and record ambient temperature continuously 

to verify that it remains within the temperature range specified in §1066.425(c)(1) throughout the 

test. Also measure humidity if required, such as for correcting NOx emissions, or meeting the 

requirements of §1066.425(d). 

(j) For vehicles at or below 14,000 pounds GVWR, determine overall driver accuracy as follows:

(1) Compare the following drive cycle metrics, based on measured vehicle speeds, to a reference 

value based on the target cycle that would have been generated by driving exactly to the target 

trace as described in SAE J2951 (incorporated by reference in §1066.1010).

(i) Determine the Energy Economy Rating as described in Section 5.4 of SAE J2951. 

(ii) Determine the Absolute Speed Change Rating as described in Section 6.1.2 of SAE J2951.

(iii) Calculate the Inertia Work Rating, IR, using the both the sums of the incremental driven and 

the target inertia work as described in Eq. 1066.430-1.

i i jj

j j

ID D IT T

i=1 j=1

IT T

j=1

100

n m

m

FD FD

IR

F D

     

 



 

 



 Eq. 1066.430-1

Where:

i FID = the driven inertial force over an interval i, as described by Equation 18 of SAE J2951.

j FID = the target inertial force over an interval j, as described by Equation 19 of SAE J2951.

Di D = the incremental driven distance over an interval i, as described by Equation 12 of SAE

J2951.

Dj D = the incremental target distance over an interval j, as described by Equation 13 of SAE

J2951.

(2) The standard-setting part may require you to provide to us 10 Hz data to characterize both 

target and actual values for cycle energy. Calculate target values based on the vehicles speeds 

from the specified test cycle.

Deleted: 4

Deleted: and correct for

Deleted: as described in 40 CFR 1065.550

Deleted: l

Deleted: m

Deleted: temperature and 

Deleted: , as 

Deleted: For testing vehicles with the following 

engines, you must record ambient temperature 

continuously to verify that it remains within the 

temperature range specified in §1066.420(b)(1) 

throughout the test:¶

(1) Air-cooled engines.¶

(2) Engines equipped with emission control devices 

that sense and respond to ambient temperature.¶

(3) Any other engine for which good engineering 

judgment indicates that this is necessary to remain 

consistent with 40 CFR 1065.10(c)(1).

Deleted: with GVWR 

Deleted: lbs

Deleted: n

Deleted: energy

Deleted: energy 

Deleted: Section 5.1.9 of 

Deleted: of the driven cycle energy trace for the 

test cycle compared to the target drive cycle energy 

trace.

Deleted: ¶

(3) Determine the inertial work ratio as described in 

Section 7.2.3 of SAE J2951.
Subpart F—Hybrids and Electric Vehicles

§1066.501 Overview. 

For HEV, PHEV, and pure electric vehicle (EV), use the following procedures:

(a) Correct the results for Net Energy Change of the RESS as follows: 

(1) For vehicles at or below 14,000 pounds GVWR, follow SAE J1711 (incorporated by 

reference in §1066.1010) except as noted in this paragraph (a). Use ±1 % of reading or ±0.3 % 

of full scale, whichever is greater, in place of the current measurement accuracy in Section 4.2a

of SAE J1711.

(2) For vehicles above 14,000 pounds GVWR, follow SAE J2711 (incorporated by reference in 

§1066.1010) for requirements related to charge-sustaining operation. 

(3) For pure EVs, irrespective of GVWR, follow SAE J1634 (incorporated by reference in 

§1066.1010).

(b) This paragraph (b) applies for vehicles that include an engine-powered generator or other 

auxiliary power unit that provides motive power. For example, this would include a vehicle that 

has a small gasoline engine that generates electricity to charge batteries. Unless we approve 

otherwise, measure emissions for all test cycles when such an engine is operating. For each test 

cycle for which emissions are not measured, you must validate that such engines are not

operating at any time during the test cycle.

Deleted: To correct

Deleted: fuel economy or emission

Deleted: results for Net Energy Change of the 

RESS

Deleted: with GVWR 

Deleted: lbs

Deleted: 1

Deleted: b

Deleted: with GVWR 

Deleted: lbs 

Deleted: specified 

Deleted: in SAE J2711 (incorporated by reference 

in §1066.710)

Deleted: c

Deleted: electric vehicles (

Deleted: )

Deleted: indirectly 
Subpart G—Calculations 

§1066.601 Overview. 

(a) The calculations described in this subpart apply as specified elsewhere in this part. This 

subpart describes how to– 

(1) Use the signals recorded before, during, and after an emission test to calculate distancespecific emissions of each regulated pollutant. 

(2) Perform calculations for calibrations and performance checks. 

(3) Determine statistical values. 

(b) You may use data from multiple systems to calculate test results for a single emission test, 

consistent with good engineering judgment. You may also make multiple measurements from a 

single batch sample, such as multiple weighing of a PM filter or multiple readings from a bag 

sample. You may not use test results from multiple emission tests to report emissions. We allow 

weighted means where appropriate. You may discard statistical outliers, but you must report all 

results. 

§1066.610 Mass-based and molar-based exhaust emission calculations. 

(a) Calculate your total mass of emissions over a test cycle as specified in paragraph (c) of this 

section or in 40 CFR part 1065, subpart G, as applicable. 

(b) For composite emission calculations over multiple test intervals and corresponding weighting 

factors, see the standard-setting part. 

(c) To calculate total mass emissions, multiply a concentration by its respective flow and density

as specified in Eq. 1066.610-1. Before calculating mass emissions as specified in paragraph (d) 

and (e) of this section, perform the following sequence of preliminary calculations to correct 

recorded concentration measurements:

(1) For vehicles above 14,000 pounds GVWR, correct all THC and CH4 concentrations for initial 

contamination as described in 40 CFR 1065.660(a), including continuous readings, sample bags 

readings, and dilution air background readings. This correction is optional for vehicles at or 

below 14,000 pounds GVWR.

(2) Correct all concentrations measured on a “dry” basis to a “wet” basis, including dilution air 

background concentrations.

(3) Calculate all NMHC and CH4 concentrations, including dilution air background 

concentrations, as described in 40 CFR 1065.660.

(4) For vehicles at or below 14,000 pounds GVWR, calculate HC concentrations, including 

dilution air background concentrations, as described in this section and §1066.665 for NMOG. 

For emission testing of vehicles above 14,000 pounds GVWR, with fuels that contain 25% or 

more oxygenated compounds by volume, calculate HC concentrations, including dilution air 

background concentrations, as described in 40 CFR part 1065, subpart I, for THCE and NMHCE.

(5) Correct all NOx emission values for test cell ambient air humidity as described in §1066.630.

(6) Correct all gaseous concentrations for dilution air background as described in §1066.620.

(7) Correct all PM filter masses for sample media buoyancy as described in 40 CFR 1065.690.

(d) Calculate the emission mass of each gaseous pollutant using the following equation:

m V xc [emission] mix [emission] [emission]    

 Eq. 1066.610-1

Deleted: using the equations

Deleted: 40 CFR 86.144 or 

Deleted: phase

Deleted: or subpart I

Deleted: the 

Deleted: of an 

Deleted: For all systems, make preliminary 

calculations as described in paragraph (c) of this 

section to correct concentrations.¶

(1) Concentration corrections. Perform the following 

sequence of preliminary calculations on recorded 

concentrations before calculating mass emissions as 

specified in paragraph (d) of this section:

Deleted: 2

Deleted: with GVWR 

Deleted: lbs

Deleted: C

Deleted: with GVWR 

Deleted: lbs

Deleted: 3

Deleted: 4

Deleted: 5

Deleted: with GVWR 

Deleted: emission testing with any oxygenated 

fuel

Deleted: any 

Deleted: in 40 CFR part 1065, subpart I, for THCE 

and NMHCE, and 

Deleted: , depending on the requirements of the 

standardsetting part

Deleted: 6

Deleted: 40 CFR 

Deleted: 7

Deleted: 40 CFR 

Deleted: 8

Deleted: in air 
Where:

m[emission] = emission mass over the test interval.

Vmix = total dilute exhaust volume over the test interval at standard reference conditions, 

corrected for any volume removed for emission sampling and the addition of secondary dilution 

air (if applicable).

ρ[emission] = density of the appropriate chemical species as given in §1066.1005(f).

x[emission] = measured emission concentration in the sample, after dry-to-wet and background 

corrections.

c = 10-2 for emission concentrations % and 10-6 for emission concentrations in ppm.

Example:

Vmix = 170.877 m3 (from paragraph (f) of this section) 

ρNOx = 1913 g/m3

xNOx = 0.9721 ppm

c = 10-6

6

NOx m 170.877 1913 0.9721 10 0.3177 g    

(e) The calculation of PM is dependent on how many PM filters are used (for example as 

described in §1066.822(b)), as follows:

(1) Except as specified in pargraphs (e)(2) and (3) of this section, calculate mPM using the 

following equation:

  mix

PM PMfil PMbkgnd

PMstd sdastd

V m mm V V

        

 Eq. 1066.610-2

Where:

mPM = mass of particulate matter emissions over the test interval.

Vmix = total dilute exhaust volume over the test interval at standard reference conditions , 

corrected for any volume removed for emissions sampling and the addition of secondary dilution 

air (if applicable).

Vsdastd = total volume of secondary dilution air flow sampled through the filter over the test phase

at standard temperature and pressure.

mPMfil = mass of particulate matter emissions on the filter over the test interval.

mPMbkgnd = mass of particulate matter on the background filter.

Example:

Vmix = 170.877 m3 (from paragraph (f) of this section)

VPMstd = 0.9246 m3 (from paragraph (f) of this section)

Vsdastd = 0.527 m3 (from paragraph (f) of this section)

mPMfil = 0.0000045 g

mPMbkgnd = 0.0000014 g

PM   170.877 0.0000045 0.0000014 0.00133 g 0.9246 0.527 m          

(2) If you sample PM onto a single filter as described in §1066.820(b)(4), calculate mPM using 

the following equation:

Deleted: mass of ...missions...mass over the test ... [3]

Deleted: phase...nterval at standard reference ... [4]

Deleted: emission 

Deleted: amount of 

Deleted: measured in ... and 10-6 for emission ... [5]

Deleted: 925...77 m3 (from paragraph (e ... [6]

Deleted: ....13 k ... [7]

Deleted: 663

Deleted: Calculate the mass of particulate matter 

emission...as follows:: ... [8]

Deleted: If you sample PM onto a single filter per 

test phase as described in §1066.822(c) or onto a ... [9]

Deleted: §1066.820(b)

Deleted: (4),

Deleted: Equation

Deleted: Eq. 1066.610-2.

Deleted: phase

Deleted: phase...nterval at standard reference ... [10]

Deleted: Vgasstd = total volume of sample flow ... [11]

Deleted: flow 

Deleted: through the filter over the test phase at ... [12]

Deleted: phase

Deleted: Vmixstd = total dilute exhaust volume over ... [13]

Deleted: Using 

Deleted: Equation

Deleted: Eq. 1066.610-

Deleted: 3

Deleted: 5¶ ... [14]

Deleted: Equation

Deleted: Eq. 1066.610-

Deleted: 3

Deleted: 5¶ ... [15]

Deleted: Equation

Deleted: Eq. 1066.610-

Deleted: 3

Deleted: 5¶ ... [16]

Deleted: Equation

Deleted: Eq. 1066.610-

Deleted: 3

Deleted: 5¶ ... [17]

Deleted: for all test phases ...s described in ... [18]

Deleted: Equation

Deleted: Eq. 1066.610-3.
        mix

PM PMfil PMbkgnd

ct-PMstd ct-sdastd ht-PMstd ht-sdastd

s-PMstd s-sdastd 0.43 0.57

V m mm VV VV

V V

   

      

 Eq. 1066.610-3

Where:

mPM = mass of particulate matter emissions over the entire FTP as sampled according to 

§1066.820(b)(1).

Vmix = total dilute exhaust volume over the test interval at standard reference conditions, 

corrected for any volume removed for emissions sampling and the addition of secondary dilution 

air (if applicable).

V[interval]-PMstd = total volume of dilute exhaust sampled through the filter over the test interval (ct 

= cold transient, s = stabilized, ht = hot transient) at standard reference conditions.

V[interval]-sdastd = total volume of secondary dilution air sampled through the filter over the test 

interval (ct = cold transient, s = stabilized, ht = hot transient) at standard reference conditions.

mPMfil = mass of particulate matter emissions on the filter over the test interval.

mPMbkgnd = mass of particulate matter on the background filter.

Example:

Vmix = 633.69 m3

Vct-PMstd = 0.9248 m3

Vct-sdastd = 0.527 m3

Vs-PMstd = 1.9676 m3

Vs-sdastd = 1.1212 m3

Vht-PMstd = 1.1215 m3

Vht-sdastd = 0.639 m3

mPMfil = 0.0000106 g

mPMbkgnd = 0.0000014 g

      PM   633.69 0.0000106 0.0000014

0.9248 0.527 1.1215 0.639

1.9676 1.1212

0.43 0.57

m

   

      

mPM

= 0.00223 g

(3) If you sample PM onto a single filter as described in §1066.820(b)(5), calculate mPM using 

the following equation:

        mix

PM PMfil PMbkgnd

ct-PMstd ct-sdastd cs-PMstd cs-sdastd ht-PMstd ht-sdastd hs-PMstd hs-sdastd

0.43 0.57

V m m m VV VV VV VV

   

         

 Eq. 1066.610-4

Where:

Deleted: phase

Deleted: of 293.15 K and 101.3 kPa

Deleted: phase

Deleted: phase

Deleted: temperature and pressure

Deleted: phase

Deleted: phase

Deleted: temperature and pressure

Deleted: phase

Deleted: for all test phases 

Deleted: 2

Deleted: Equation

Deleted: Eq. 1066.610-4.
mPM = mass of particulate matter emissions over the entire FTP as sampled according to 

§1066.820(b)(2).

Vmix = total dilute exhaust volume over the test interval at standard reference conditions, 

corrected for any volume removed for emissions sampling and the addition of secondary dilution 

air (if applicable).

V[interval]-PMstd = total volume of dilute exhaust sampled through the filter over the test interval (ct 

= cold transient, cs = cold stabilized, ht = hot transient, hs = hot stabilized) at standard reference 

conditions.

V[interval]-sdastd = total volume of secondary dilution air sampled through the filter over the test 

interval (ct = cold transient, cs = cold stabilized, ht = hot transient, hs = hot stabilized) at 

standard reference conditions.

mPMfil = mass of particulate matter emissions on the filter over the test interval.

mPMbkgnd = mass of particulate matter on the background filter.

Example:

Vmix = 972.12 m3

Vct-PMstd = 0.9236 m3

Vct-sdastd = 0.529 m3

Vcs-PMstd = 1.9666 m3

Vcs-sdastd = 1.1209 m3

Vht-PMstd = 1.1218 m3

Vht-sdastd = 0.641 m3

Vhs-PMstd = 1.9674 m3

Vhs-sdastd = 1.1213 m3

mPMfil = 0.0000229 g

mPMbkgnd = 0.0000014 g

      PM   972.12 0.0000229 0.0000014

0.9236 0.529 1.9666 1.1209 1.1218 0.641 1.9674 1.1213

0.43 0.57

m

   

        

mPM = 0.00155 g

(f) This paragraph (f) describes how to correct flow and flow rates to standard reference 

conditions and provides an example of how to determine Vmix based on CVS total flow and the 

removal of sample flow from the dilute exhaust gas.

(1)Correct flow and flow rates to standard reference conditions as needed using the following 

equation:

[flow]act in std

[flow]std

std in

V pT V

p T

   

 Eq. 1066.610-5

Where:

V[flow]std = total volume of flow at the flow meter at standard reference conditions.

V[flow]act = total volume of flow at the flow meter at test conditions.

pin = flow meter inlet absolute static pressure. Measure absolute static pressure directly or 

calculate it as the sum of atmospheric pressure plus a differential pressure that is referenced to 

atmospheric pressure.

Deleted: phase

Deleted: of 293.15 K and 101.3 kPa

Deleted: phase

Deleted: phase

Deleted: cold 

Deleted: temperature and pressure

Deleted: phase

Deleted: phase

Deleted: temperature and pressure

Deleted: phase

Comment [CAL2]: Alan, please review. 

Deleted: temperature and pressure 

Deleted: 3

Deleted: temperature and pressure

Deleted: p

Deleted: B

Deleted: atmos = 

Deleted: barometric 

Deleted: atmospheric pressure.¶

Deleted: gauge pressure 

Deleted: elevation above ambient 

Deleted: at the sampler 

Deleted: (for most flow meters this can be set 

equal to 0)
Tstd = standard temperature.

pstd = standard pressure.

Tin = average temperature of the dilute exhaust sample at the flow meter inlet.

Example:

VPMact = 1.07 m3

pin = 101.7 kPa

Tstd = 293.15 K

pstd = 101.325 kPa

Tin = 340.5 K

3

PMstd

1.07 101.7 293.15 0.9246 m

101.325 340.5

V     

(2) The following example provides a determination of Vmix based on CVS total flow and the 

removal of sample flow from one dilute exhaust gas analyzer and one PM sampler that is 

utilizing secondary dilution. Note that your Vmix determination may vary from Eq. 1066.610-6 

based on the number of flows that are removed from your dilute exhaust gas and whether your 

PM sampler is using secondary dilution. For this example, Vmix is governed by the following 

equation:

VV V V V mix CVSstd gasstd PMstd sdastd  

 Eq. 1066.610-6

Where:

VCVSstd = total dilute exhaust volume over the test interval at the flow meter at standard reference 

conditions.

Vgasstd = total volume of sample flow through the gaseous emission bench over the test interval at 

standard reference conditions.

VPMstd = total volume of dilute exhaust sampled through the filter over the test interval at 

standard reference conditions.

Vsdastd = total volume of secondary dilution air flow sampled through the filter over the test 

interval at standard reference conditions.

Example:

Using Eq. 1066.610-5

VCVSstd = 170.492 m3, where VCVSact = 170.72 m3, pin = 101.7 kPa, and Tin = 294.7 K

Using Eq. 1066.610-5

Vgasstd = 0.0291 m3, where Vgasact = 0.0337 m3, pin = 101.7 kPa, and Tin = 340.5 K

Using Eq. 1066.610-5

VPMstd = 0.9246 m3, where VPMact = 1.07 m3, pin = 101.7 kPa, and Tin = 340.5 K

Using Eq. 1066.610-5

Vsdastd = 0.527 m3, where Vsdaact = 0.531 m3, pin = 101.7 kPa, and Tin = 296.3 K

Vmix = 170.445 + 0.0291 + 0.9246 – 0.527 = 170.877 m3

§1066.620 Dilution air background correction.

(a) Correct the emissions in a gaseous sample for background using the following equation:

Deleted: , 293.15 K

Deleted: Pstd = standard pressure, 101.3 kPa.¶

Deleted: B

Deleted: atmos

Deleted: pin = 0 kPa¶

Deleted: Tstd = 293.15 K¶

pstd = 101.3 kPa¶

Deleted: atmos

Deleted: , pin = 0 kPa

Deleted: atmos

Deleted: pin = 0 kPa, 

Deleted: atmos

Deleted: , pin = 0 kPa

Deleted: atmos

Deleted: , pin = 0 kPa

Deleted: emission 

Deleted: as follows
[emission] [emission]dexh [emission]bkgnd

1 xx x 1

DF

              

 Eq. 1066.620-1

Where:

x[emission]dexh = measured emission concentration in dilute exhaust (after dry-to-wet correction for 

dry measurements).

x[emission]bkgnd = measured emission concentration in the dilution air (after dry-to-wet correction

for dry measurements).

DF = dilution factor determined in paragraph (b) of this section.

Example:

xNOxdexh = 1.08305 ppm

xNOxbkgnd = 0.12456 ppm

DF = 9.14506

NOx

1 1.08305 0.12456 1 0.97211 ppm 9.14506 x                

(b) Determine the dilution factor, DF, over the test interval using the following equation:

 Eq. 1066.620-2

Where:

xCO2 = amount of CO2 measured in the sample over the test interval.

xNMHC = amount of C1-equivalent NMHC measured in the sample over the test interval.

xCH4 = amount of CH4 measured in the sample over the test interval.

xCO = amount of CO measured in the sample over the test interval.

 = atomic hydrogen-to-carbon ratio of the test. You may measure  or use default values from 

Table 1 of 40 CFR 1065.655.

 = atomic oxygen-to-carbon ratio of the test fuel. You may measure  or use default values 

from Table 1 of 40 CFR 1065.655.

Example:

xCO2 = 1.456 % = 0.01456

xNMHC = 0.84 ppm = 0.00000084

xCH4 = 0.26 ppm = 0.00000026

xCO = 80.4 ppm = 0.0000804

 = 1.92

 = 0.03

CO2 NMHC CH4 CO

1

1 3.76 1 ( ) 2 42

DF

x x xx                     

Deleted: amount of 

Deleted: ,

Deleted: emissions measured 

Deleted: ed

Deleted: amount of 

Deleted: ,

Deleted: ed

Deleted: emissions measured 

Deleted: §1066.620(b)

Deleted: 7411

Deleted: 5

Deleted: 1

Deleted: 659

Deleted: 6

Deleted: phase

Deleted: Equation

Deleted: Eq. 1066.620-2. Note that for 

determination of  and  you may use measured fuel 

properties or the default fuel properties in Table 1 of 

40 CFR 1065.655.¶

CO2 THC CO

1 100

1 3.76 1

2 42 DF xxx

               

¶

¶

Eq. 1066.620-2¶

Deleted: phase

Deleted: T

Deleted: T

Deleted: phase

Deleted: phase

Deleted: mixture of fuel(s) being combusted, 

weighted by molar composition

Deleted: mixture of fuel(s) being combusted, 

weighted by molar composition

Deleted: T

Deleted: 1.1

Deleted: 0

Deleted: 11

Deleted: %

Deleted: %

Deleted: 85
 

1 9.14506

1.92 1.92 0.03 1 3.76 1 0.01456 0.00000084 0.00000026 0.0000804

2 42

DF                      

(c) Determine the dilution factor, DF, over the test interval for partial flow dilution sample 

systems that measure PM using the following equation:

PMstd

exhstd

V DF

V



 Eq. 1066.620-3

Where:

VPMstd = total dilute exhaust volume sampled through the filter over the test interval at standard 

reference conditions.

Vexhstd = total exhaust volume sampled from the vehicle at standard reference conditions.

Example:

VPMstd = 170.9 m3

Vexhstd = 15.9 m3

170.9 11.1

15.4

DF  

(d) Determine the time weighted dilution factor, DFw, over the duty cycle using the following 

equation:

i

i 1

w

i

i 1 i

1

N

N

t

DF

t

DF













 Eq. 1066.620-4

Where:

N = number of test intervals.

i = test interval number

t = duration of the test interval.

DF = dilution factor over the test interval.

Example:

N = 3

DF1 = 14.80

t1 = 505 s

DF2 = 24.48

t2 = 867 s

DF3 = 17.28

t3 = 505 s

w

505 867 505 18.82

111 505 867 505

14.80 24.48 17.28

DF                   

Deleted: phase

Deleted: Equation

Deleted: Eq. 1066.620-3.

Deleted: phase

Deleted: of 293.15 K and 101.3 kPa

Deleted: dilute 

Deleted: CVS

Deleted: reference 

Deleted: of 293.15 K and 101.3 kPa

Deleted: mix

Deleted: 18.0
§1066.630 NOx intake-air humidity correction.

See the standard-setting part to determine if you may correct NOx emissions for the effects of 

intake-air humidity. Correct NOx emissions for intake-air humidity as described in this section. 

See §1066.610(c)(1) for the proper sequence for applying the NOx intake-air humidity correction.

(a) For vehicles at or below 14,000 pounds GVWR, apply a correction for any reciprocating 

engines for the following test cycles:

(1) Calculate a humidity correction using a time-weighted mean value for ambient humidity over 

the test interval. Calculate absolute ambient humidity in grams H2O vapor per kilogram of dry 

air using the following equation:

  H2O d

air atmos d

1000 % 0.01

% 0.01

M p RH H

M p p RH

      

 Eq. 1066.630-1

Where:

MH2O = molar mass of H2O, in g/mol.

pd = saturated vapor pressure at the ambient dry bulb temperature, in kPa.

RH% = relative humidity of ambient air, in %.

Mair = molar mass of air, in g/mol.

patmos = atmospheric pressure, in kPa.

Example:

MH2O = 18.01528 g/mol

pd = 2.93 kPa

RH % = 37.5 %

Mair = 28.96559 g/mol

patmos = 96.71 kPa

  2

1000 18.01528 2.93 37.5 0.01 7.14741 g H O vapor kg dry air 28.96559 96.71 2.93 37.5 0.01

H      

(2) Use the following equation to correct measured concentrations to a reference condition of 

10.71 grams H2O vapor per kilogram of dry air for the FTP, US06, LA-92, SC03, and HFET test 

cycles:

 

s

NOxdexhcor NOxdexh 1 0.0329 10.71

H x x H    

 Eq. 1066.630-2

Where:

xNOxdexh = measured dilute NOx emissions.

Hs = humidity scale. Set = 1 for FTP, US06, LA-92, and HFET test cycles. Set = 0.8825 for the 

SC03 test cycle.

H = absolute humidity, from paragraph (a)(1) of this section.

Example:

H = 7.14741 g H2O vapor/kg dry air

xNOxdexh = 1.21 ppm

Deleted: and temperature 

Deleted: s

Deleted: or temperature

Deleted: and temperature 

Deleted: s

Deleted: You may use a time-weighted mean 

combustion air humidity to calculate this correction 

if your combustion air humidity remains within a 

tolerance of ± 5% of the mean combustion air 

humidity value over the test phase.

Deleted: with GVWR 

Deleted: lbs

Deleted: 1

Deleted: For the FTP, US06, LA-92 AC1, and 

AC2, and HFET test cycles, u

Deleted: of 

Deleted: Eq. 1066.630-1¶

 

H2O d

air atmos d

%

%

M RH p H

M p p RH

     ¶

Deleted: A

Deleted: in grams of H2O vapor per kilogram of 

dry air

Deleted: MH2O = molar mass of H2O in g/mol.¶

RH = Relative humidity of ambient air.¶

Mair = molar mass of air in kg/mol.¶

pd = Saturated vapor pressure at the ambient dry bulb 

temperature.¶

pB = barometric pressure.¶

Deleted: MH2O = 18.01528 g/mol¶

R

Deleted: %

Deleted: 37.5 %

Deleted: Mair = 0.02896559 kg/mol¶

Pd = 2.93 kPa¶

PB = 96.71 kPa¶
  NOxdexhcor

1 1.21 1.08305 ppm 1 0.0329 7.14741 10.71 x    

(b) For vehicles above 14,000 pounds GVWR, apply correction factors as described in 40 CFR 

1065.670.

§1066.640 Removed water correction.

Correct for removed water if water removal occurs upstream of a concentration measurement

and downstream of a flow meter used to determine mass emissions over a test interval. Perform 

this correction based on the amount of water at the concentration measurement and on the 

amount of water at the flow meter.

§1066.650 Flow meter calibration calculations.

This section describes how to calibrate various flow meters based on mass flow rates. Calibrate 

your flow meter according to 40 CFR 1065.640 instead if you calculate emissions based on 

molar flow rates.

(a) PDP calibration calculations. Perform the following steps to calibrate a PDP flow meter:

(1) Calculate PDP volume pumped per revolution, Vrev, for each restrictor position from the 

mean values determined in §1066.140:

ref in std

rev

nPDP in std

QTp V

f p T

    



Eq. 1066.650-1

Where:

Qref

 = mean flow rate of the reference flow meter.

Tin = mean temperature at the PDP inlet.

pstd = standard pressure= 101.325 kPa.

nPDP f = mean PDP speed.

in p = mean static absolute pressure at the PDP inlet.

Tstd = standard temperature= 293.15 K.

Example:

Qref

 = 0.1651 m3

/s

Tin = 299.5 K

pstd = 101.325 kPa

nPDP f = 1205.1 r/min = 20.085 r/s

in p = 98.290 kPa

Tstd = 293.15 K

Deleted: 

18.01528 37.5 0

0.02896559 96.71 2. H     

¶

Deleted: (2) For the SC03 test cycle, use the 

following equation to correct measured 

concentrations to a reference condition of 10.71 of 

H2O vapor per kilogram of dry air:¶

 NOxdexhcor NOxdexh

0.8825

1 0.0329 x x H     

¶

Eq. 1066.630-3¶

¶

Where:¶

H = Absolute humidity in grams of H2O vapor per 

kilogram of dry air according to Eq. 1066.630-2.¶

¶

Example:¶

RH = 55.9 %¶

Pd = 2.93 kPa¶ ... [19]

Deleted: with GVWR 

Deleted: lbs

Deleted: part 

Comment [CAL3]: Define a procedure. 

Deleted: you remove water 

Deleted: , x, correct for the removed water

Deleted: , whose flow is used to determine the 

mass emission rate or total mass over a test phase

Deleted: the calculations for calibrating 

Deleted: Calibrate flow meters as described in 40 

CFR 1065.640. Note that 

Deleted: I

Deleted: choose to 

Deleted: determine 

Deleted: , use the equations in 40 CFR 1065.640 to 

calibrate your flow meter

Deleted: calibration equations on a molar basis; 

however, 40 CFR 1065.640(a) allows for conversion ... [20]

Deleted: After you calibrate a flow meter using 

these calculations, use the calculations described in ... [21]

Deleted: b

Deleted: For each restrictor position, calculate the 

following values from the mean values determined in ... [22]

Deleted: (m3/r)

Deleted: air 

Deleted: pump inlet absolute temperature

Deleted: pump inlet absolute 

Deleted: nPDP f = mean pump speed.¶

Deleted: 101325 Pa

Deleted: ¶ ... [23]
0.1651 299.5 101.3

20.085 98.290 293.15

Vrev

    

Vrev = 0.00866 m3/r

(2) Calculate a PDP slip correction factor, Ks for each restrictor position from the mean values 

determined in §1066.140:

out in

s

nPDP out

1 p p K

f p

  

Eq. 1066.650-2

Where:

nPDP f = mean PDP speed.

out p = mean static absolute pressure at the PDP outlet.

in p = mean static absolute pressure at the PDP inlet.

Example:

nPDP f = 1205.1 r/min = 20.085 r/s

out p = 100.103 kPa

in p = 98.290 kPa

s

1 100.103 98.290

20.085 100.103

K   

Ks = 0.006700 s/r

(3) Perform a least-squares regression of Vrev, versus PDP Ks, by calculating slope, a1, and 

intercept, a0, as described in 40 CFR 1065.602.

(4) Repeat the procedure in paragraphs (a)(1) through (3) of this section for every speed that you 

run your PDP.

(5) The following example illustrates a range of typical values for different PDP speeds:

Table 1 of §1066.650–

Example of PDP calibration data

nPDP f

(r/min)

a1 

(m3/min)

a0 

(m3/r)

12.6 0.841 0.056

16.5 0.831 -0.013

20.9 0.809 0.028

23.4 0.788 -0.061

(6) For each speed at which you operate the PDP, use the appropriate regression equation from 

this paragraph (a) to calculate flow rate during emission testing as described in §1066.652.

Deleted: (s/r)

Deleted: pump 

Deleted: pump outlet 

Deleted: pump inlet absolute 

Deleted: PDP volume pumped per revolution, 

Deleted: slip correction factor, 

Deleted: §

Deleted: b

Deleted: these calculations

Deleted: 755.0

Deleted: 50.43

Deleted: 987.6

Deleted: 49.86

Deleted: 1254.5

Deleted: 48.54

Deleted: 1401.3

Deleted: 47.30

Deleted: corresponding slope, a1, and intercept, a0, 
(b) SSV calibration. Perform the following steps to calibrate an SSV flow meter:

(1) Calculate the Reynolds number, Re#, for each reference volumetric flow rate, using the throat 

diameter of the venturi, dt, and the mass air flow rate of the reference flow meter, Qm-ref

 . 

Assume an initial value for Cd = 0.98 to calculate Qm-ref

 .

# m-ref

t

66670 Q Re =  d 

 



Eq. 1066.650-3

Where:

μ = viscosity of air in centipoises calculated using Eq. 1066.650-4. 3

2 3 1.458 10

110.4

T = T     

Eq. 1066.650-4

Where:

T = the temperature at the SSV inlet in Kelvin.

If the calibration venturi is used at the tunnel inlet (free standing), then assume a value of β = 0. 

If the SSV is installed in the CVS tunnel, use the actual inside tunnel diameter and the throat 

diameter to compute β, where β is the ratio of venturi throat to inlet diameters.

(2) From the initial calibration of the venturi, establish an equation of Cd as a function of Re#. 

The following functional forms should be reviewed, but a power series, least-squares fit 

polynomial equation may result in the best fit. Many factors involved in the installation of SSV 

and the operating range of the Reynolds number can affect the functional relationship of Cd with 

Re#. Calculate Cd based on this initial equation of Re#. Compute a final Qm

 based on this 

calculated Cd for both the calibration nozzle and the inline SSV.

(3)(i) Compute the percent difference in air flow between the calibration venturi and the inline 

SSV. If the difference in percent of point is greater than 1%, compute a new Cd and Re# for the 

in-tunnel venturi as follows:

mact

dnew

mtheo

Q C =

Q





Eq. 1066.650-5

Where:

Cdnew = the ratio of actual air flow/theoretical air flow.

Qmact

 = flow measured by the calibration venturi, kg/min.

Qmtheo

 = the theoretical calculated flow based on the in-tunnel SSV conditions with Cd set equal 

to 1, kg/min.

# m-ref

new

t

0.8 Q Re =  d 

 



Eq. 1066.650-6

Where:

Deleted: d

Deleted: , of the reference flow meter

Deleted: Equation

Deleted: 3

Deleted: the 

Deleted: 4

Deleted: 5
# R new e = Reynolds number based on the calibrated venturi flow, but the in-tunnel SSV properties.

(ii) Recalculate a new curve fit of Cdnew for the inline venturi as a function of # R new e following 

the guidelines in paragraph (b)(1) of this section. Agreement of the fit should be within 1.0 % of 

point. Install the new Cd curve fit in the test cell flow computing device and conduct the propane 

injection flow verification test as described in 40 CFR 1065.341.

(c) CFV calibration. Some CFV flow meters consist of a single venturi and some consist of 

multiple venturis, where different combinations of venturis are used to meter different flow rates. 

For CFV flow meters that consist of multiple venturis, either calibrate each venturi 

independently to determine a separate calibration coefficient, Kv, for each venturi, or calibrate 

each combination of venturis as one venturi by determining Kv for the system.

(1) To determine Kv for a single venturi or a combination of venturis, perform the following 

steps:

(i) Calculate an individual Kv for each calibration set point for each restrictor position using the 

following equation:

refstd in

v

in

Q T K =

p

 

Eq. 1066.650-7

Where:

Qrefstd

 = mean flow rate from the reference flow meter, at standard reference conditions.

Tin = mean temperature at the venturi inlet.

in p = mean static absolute pressure at the venturi inlet.

(ii) Calculate the mean and standard deviation of all the Kv values (see 40 CFR 1065.602). 

Verify choked flow by plotting Kv as a function of in p .Kv will have a relatively constant value

for choked flow; as vacuum pressure increases, the venturi will become unchoked and Kv will 

decrease. Paragraphs (c)(1)(iii) through (viii) of this section describe how to verify your range of 

choked flow.

(iii) If the standard deviation of all the Kv values is less than or equal to 0.3 % of the mean Kv, 

use the mean Kv in Eq. 1066.652-7, and use the CFV only up to the highest venturi pressure ratio,

r, measured during calibration using the following equation:

CFV

in

1 p r p

  

Eq. 1066.650-8

Where:

pCFV = differential static pressure; venturi inlet minus venturi outlet.

(iv) If the standard deviation of all the Kv values exceeds 0.3 % of the mean Kv, omit the Kv value

corresponding to the data point collected at the highest r measured during calibration.

(v) If the number of remaining data points is less than seven, take corrective action by checking 

your calibration data or repeating the calibration process. If you repeat the calibration process, 

we recommend checking for leaks, applying tighter tolerances to measurements and allowing 

Deleted: d

Deleted: ,

Deleted: part 

Deleted: e

Deleted: the 

Deleted: single 

Deleted: For each restrictor position, use the data 

collected at 

Deleted: to calculate an individual Kv for each 

point using Eq. 1066.650-7

Deleted: 6

Deleted: of 293.15 K and 101.3 kPa

Deleted: absolute 

Deleted: according to 

Deleted: part 

Deleted: Eqs. 1065.602-1 and 1065.602-2

Deleted: P

Deleted: venturi inlet pressure

Deleted: For choked flow, 

Deleted: pressure decreases (

Deleted: )

Deleted: n

Deleted: 7
more time for flows to stabilize.

(vi) If the number of remaining Kv values is seven or greater, recalculate the mean and standard 

deviation of the remaining Kv values.

(vii) If the standard deviation of the remaining Kv values is less than or equal to 0.3 % of the 

mean of the remaining Kv, use that mean Kv in Eq 1066.652-7, and use the CFV values only up 

to the highest r associated with the remaining Kv.

(viii) If the standard deviation of the remaining Kv still exceeds 0.3 % of the mean of the 

remaining Kv values, repeat the steps in paragraph (c)(1)(iv) through (vii) of this section.

(2) During exhaust emission tests, monitor sonic flow in the CFV by monitoring the CFV 

pressure ratio. Based on the calibration data selected to meet the criteria for paragraphs 

(c)(1)(iv) and (vii) of this section, in which Kv is constant, select the data values associated with 

the calibration point with the lowest absolute venturi inlet pressure to determine the r limit. 

Calculate r during the exhaust emission test using Eq. 1066.650-8 to demonstrate that the value 

of r during all emission tests is less than or equal to the r limit derived from the CFV calibration 

data.

§1066.652 PDP, SSV, and CFV flow rate calculations.

This section describes the equations for calculating flow rates from various flow meters. After 

you calibrate a flow meter according to §1066.650, use the calculations described in this section

to calculate flow during an emission test. Calculate flow according to 40 CFR 1065.642 instead 

if you calculate emissions based on molar flow rates.

(a) PDP volumetric flow rate. Based upon the speed at which you operate the PDP for a test 

interval, select the corresponding slope, a1, and intercept, a0, as calculated in §1066.650(a), to 

calculate volumetric flow rate, Q as follows:

nPDP

rev std in

in std

VTp Q f T p    



Eq. 1066.652-1

Where:

fnPDP = pump speed.

Vrev = PDP volume pumped per revolution.

Tstd = standard temperature = 293.15 K.

pin = mean static absolute pressure at the PDP inlet.

Tin = pump inlet absolute temperature.

pstd = standard pressure= 101.325 kPa.

out p = mean static absolute pressure at the PDP outlet

nPDP

1 out in

rev 0

out

a p p V a

f p

  

Eq. 1066.652-2

Example:

a1 = 50.43 m3/min = 0.8405 m3/s

Deleted: 

Deleted: e

Deleted: i

Deleted: up

Deleted: e

Deleted: ¶

(i) 

Deleted: 7

Deleted: .¶

(ii) T

Deleted: venturi pressure ratio 

Deleted: must be

Deleted: calibration pressure ratio

Deleted: SSV

Deleted: CF

Deleted: PDP

Deleted: 40 CFR 1065.642

Deleted: If you choose to determine molar flow 

rate, use the equations in 40 CFR 1065.642 to 

calculate flow. Note that 40 CFR 1065.642 presents 

all flow rate equations on a molar basis; however, 40 

CFR 1065.640(a) allows for conversion between 

volumetric and molar flow rate. If you are using 

mass-based emission calculations to determine your 

total mass of emissions over a test cycle, you may 

determine flow rate volumetrically using Equation 

1065.640-1 to convert the molar flow rate equations 

in 40 CFR 1065.642 to volumetric flow equations.

Deleted: molar

Deleted: Pin = pump inlet absolute static pressure.¶

Tstd = standard temperature.¶

fnPDP = pump speed.¶

Deleted: pump outlet absolute temperature.¶

in p = pump inlet absolute static pressure.¶

Deleted: (

Deleted: )

Deleted: (

Deleted: )
fnPDP = 755.0 r/min = 12.58 r/s

pout = 99.950 kPa

pin = 98.575 kPa 

a0 = 0.056 m3/r

Tin = 323.5 K

rev

0.8405 99.950 98.575 0.056

12.58 99.950

V   

Vrev = 0.063 m3/r

0.06383 293.15 98.575 12.58

323.5 101.3 Q     



Q = 0.7079 m3/s

(b) SSV volumetric flow rate. Based on the Cd versus Re# equation you determined according to 

§1066.650(b), calculate SSV volumetric flow rate, Vmix, during an emission test as follows: 2

q d

1 4 1

t

s

K C Yd Q p 

 

      



Eq. 1066.652-3

Where:

Q = air flow rate of flow meter, scfm (m3

/min).

Kq = 0.0021074 for SI units; = 1 for English units.

ρs = density of air at standard conditions = 1.2041, kg/m3.

Cd = discharge coefficient.

Y = Expansion factor, as determined in paragraph (b)(1) of this section.

dt = venturi throat diameter, inch (mm).

β = ratio of venturi throat diameter to approach pipe diameter.

ρ1 = density of air at inlet conditions, lbm/ft3 (kg/m3), as determined in paragraph (b)(2) of this 

section.

Δp = pressure drop between inlet and throat, inches H2O (kPa).

(1) The expansion factor (Y) is calculated as follows: 1

1 2

2 4

k

2

4

1 1

1 1 1

k

k

k

k r Y r

k r r





      

                                          

Eq. 1066.652-4

Where:

1

abs

p r p  

d

D  

d = venturi throat diameter in inches (m).

D = inlet pipe diameter in inches (m).

Deleted: (

Deleted: )

Deleted: Cp = 1000 (J·/m-3)/kPa¶

Ct = 60 s/min¶

Deleted: 83

Deleted: molar

Comment [CAL4]: Make sure all the English 

units (and abbreviations) are captured in subpart K. 

Deleted: (

Deleted: conversion)

Deleted: lbm/ft3 (

Deleted: ) as specifieddetermined in paragraph 

(b)(4) of this section

Deleted: specified 

Deleted: .

Deleted: m

Deleted: m
k = ratio of specific heats (1.40 for air).

(2) Calculate the inlet density ρ1, as follows:

abs

1

mix abs

p

R T   

Eq. 1066.652-5

Where:

pabs= p1 + atmospheric pressure.

Tin = venturi inlet absolute temperature.

mix

8.3144 kJ/(kg mol K) Rmix MW

  

MWmix = the molecular weight of the mix, as calculated in paragraph (b)(3) of this section.

(3) Calculate the molecular weight of the mix as follows:

  2 air abs v H O v

mix

abs

MW p p MW p MW

p

   

Eq. 1066.652-6

Where:

MWair = 28.964 kg/mol

pabs = ?pv = vapor pressure, in Hg (kPa)

MWH20 = 18.015 kg/mol

(c) CFV volumetric flow rate. Some CFV flow meters consist of a single venturi and some 

consist of multiple venturis, where different combinations of venturis are used to meter different 

flow rates. If you use multiple venturis and you calibrated each venturi independently to 

determine a separate calibration coefficient, Kv, for each venturi, calculate the individual 

volumetric flow rates through each venturi and sum all their flow rates to determineQ . If you 

use multiple venturis and you calibrated each combination of venturis, calculate Q using the Kv

that was determined for that combination of venturis.

(1) To calculate volumetric flow rate through one venturi or a combination of venturis, use the 

mean Kv you determined according to §1066.650(c) and calculate the appropriate volumetric

flow rate, Q , during an emission test as follows:

v in

in

K p Q = T 

Eq. 1066.652-7

Where:

Q = air flow rate of flow meter, in m3/s.

Kv = flow meter calibration coefficient, in m3·K1/2/(kPa·s).

Tin = temperature at the venturi inlet, in K.

pin = absolute static pressure at the venturi inlet, in kPa.

Example: 

Kv = 0.074954 m3·K1/2/(kPa·s)

Deleted: T

Deleted: (

Deleted: )

Deleted: is calculated 

Comment [CAL5]: This appears to be circular 

with equation 1066.652-5. 

Deleted: barometric 

Deleted: abs

Deleted: T1 + 273.15

Deleted: Rmix = Ru/MWmix¶

Deleted: Ru = 8.3144 kJ/kg·mole·K¶

Deleted: T

Deleted: ,

Deleted: is calculated 

Deleted: MWair = 28.964 kg/kg·mole¶

Deleted: kg·

Deleted: e¶

(4) The density at standard conditions of 101.33 kPa 

and 20 °C is calculated as follows:¶

101.325 1.2041 kg/ 8.314472 293.15

28.96559

s  



Deleted: molar

Deleted: one 

Deleted: its respective 

Deleted: its 

Deleted: ,

Deleted: Where:¶

Deleted: P

Deleted: 000
pin = 99

.654 kPa

Tin = 353.15 K

0.074954 99.654

353.15

Q





Q = 0.39748 m

3

/s Deleted: 461
§1066.665 NMOG determination.

For vehicles subject to an NMOG standard, determine NMOG as described in paragraph (a) of 

this section. Except as specified in the standard-setting part, you may alternatively calculate 

NMOG results based on measured NMHC emissions as described in paragraphs (c) through (f) 

of this section.

(a) Determine NMOG by independently measuring alcohols and carbonyls as described in 40 

CFR 1065.805 and 1065.845. Use good engineering judgment to determine which alcohols and 

carbonyls you need to measure. This would typically require you to measure all alcohols and 

carbonyls that you expect to contribute 1% or more of total NMOG emissions. Calculate NMOG

with the following equation, using density values specified in §1066.1005(f):

OHCi

NMOG NMHC NMHC OHCi[THC-FID] OHCi

1 1 OHCi

N N

i i

m m m RF m    

     

Eq. 1066.665-1

Where:

mNMOG = the sum of the mass of NMOG in the exhaust.

mNMHC = the mass of NMHC and all oxygenated hydrocarbons (OHCs) in the exhaust, as 

determined using Eq. 1066.610-1. Calculate NMHC mass based on ρNMHC.

ρNMHC = the effective C1-equivalent density of NMHC as specified in §1066.1005(f):.

mOHCi = the mass of oxygenated species i in the exhaust calculated using Eq. 1066.610-1.

ρOCHi = the C1-equivalent density of oxygenated species i.

RFOHCi[THC-FID] = The response factor of a THC-FID to oxygenated species i relative to propane 

on a C1-equivalent basis as determined in 40 CFR 1065.665.

(b) The following example shows how to determine NMOG emissions as described in paragraph 

(a) of this section for (OHC) compounds including ethanol (C2H5OH), methanol (CH3OH), 

acetaldehyde (C2H4O), and formaldehyde (C2HO) as C1-equivalent concentrations:

mNMHC = 0.0125 g

mCH3OH = 0.0002 g

mC2H5OH = 0.0009 g

mHCHO = 0.0001 g

mC2H4O = 0.00005 g

RFCH3OH[THC-FID] = 0.63

RFC2H5OH[THC-FID] = 0.75

RFHCHO[THC-FID] = 0.00

RFC2H4O[THC-FID] = 0.50

ρNMHC-liq = 576.816 g/m3

ρCH3OH = 1332.02 g/m3

ρC2H5OH = 957.559 g/m3

ρHCHO = 1248.21 g/m3

ρC2H4O = 915.658 g/m3

NMOG

0.0002 0.0009 0.63 0.75

1332.02 957.559 0.0125 576.816

0.0001 0.00005 0.00 0.5

1248.21 915.658

0.0002 0.0009 0.0001 0.00005

m

     

  

   



 

Deleted: e

Deleted: See

Deleted: Unless the standard-setting part specifies 

otherwise, u...se good engineering judgment to ... [24]

Deleted: s

Deleted: ¶

Deleted: C1-equivalent 

Deleted: mOHCi = the C1-equivalent mass of 

oxygenated species i in the exhaust calculated using 

Eq. 1066.610-1 and the density of the oxygenated 

species i as given in §1066.1005(f).¶ ... [25]

Deleted: Equation

Deleted: Note that the effective density used for 

NMHC mass determination should be based on 

ρNMHC-liq as given in §1066.1005(f).

Deleted: -liq...= the effective C1-equivalent density ... [26]

Deleted: as given in §1066.1005(f)

Deleted: the

Deleted: You may generate your own response 

factors or use the following response factors, 

consistent with good engineering judgment:¶

¶

Table 1 of §1066.665–Default values for THC FID ¶

response factor relative to propane on a C1-

equivalent basis¶

Compound ... [27]

Deleted: b

Deleted: based on 

Deleted: HCHO

Deleted: 000...125 k ... [28]

Deleted: 000...002 k ... [29]

Deleted: 000...009 k ... [30]

Deleted: 000...001 k ... [31]

Deleted: 000... k ... [32]

Deleted: 0....76.816 k ... [33]

Deleted: ....32.02 k ... [34]

Deleted: 0....57.559 k ... [35]

Deleted: ....48.21 k ... [36]

Deleted: 0....15.658 k ... [37]
mNMOG = 0.013273

(c) For ethanol-gasoline blends less than 25 % ethanol by volume, you may calculate NMOG 

emissions from measured NMHC emissions as follows:

(1) For hot start and hot running test cycles or intervals other than the FTP, you may determine 

NMOG based on the test cycle NMHC emission rate using the following equation:

NMOGhot NMHChot e e  1.03

Eq. 1066.665-2

Where:

eNMOGhot = mass emission rate of NMOG over the hot running test cycle.

eNMHChot = mass emission rate of NMHC over the hot running test cycle, calculated using ρNMHCliq.

Example:

eNMHChot = 0.025 g/mi

NMOGhot e   0.025 1.03 0.026 g/mi

(2) You may determine weighted composite NMOG for FTP testing based on the weighted 

composite NMHC emission rate and the volume percent of ethanol in the fuel using the 

following equation:

e e VP NMOGcomp NMHCcomp EtOH      1.0302 0.0071

Eq. 1066.665-3

Where:

eNMOGcomp = weighted composite mass emission rate of NMOG.

eNMHCcomp = weighted composite mass emission rate of NMHC, calculated using ρNMHC-liq.

VPEtOH = volume percentage of ethanol in the test fuel. Use good engineering judgment to 

determine this value either as specified in 40 CFR 1065.710 or based on blending volumes, 

taking into account any denaturant.

Example:

eNMHCcomp = 0.025 g/mi

VPEtOH = 15.1 %

eNMOGcomp     0.025 1.0302 0.0071 15.1 0.0284 g/mi  

(3) You may determine NMOG for the complete FTP cold start test interval for use in fuel 

economy and CREE calculations based on the NMHC emission rate for the test interval and the 

volume percent of ethanol in the fuel using the following equation:

e e VP NMOG-FTPct NMHC-FTPct EtOH    1.0246 0.0079 

Eq. 1066.665-4

Where:

eNMOG-FTPct = mass emission rate of NMOG over the FTP cold start test interval.

eNMHC-FTPct = mass emission rate of NMHC over the FTP cold start test interval, calculated using

ρNMHC-liq.

VPEtOH = volume percentage of ethanol in the test fuel.

Deleted: ranging from E0 to E25

Deleted: using the following equations

Deleted: phase

Deleted: for use in criteria pollutant, fuel economy,

and carbon-related exhaust emission calculations 

Deleted: Equation

Deleted: Eq. 1066.665-2.

Deleted: as given in §1066.1005(f)

Deleted: comp

Deleted: 000

Deleted: k

Deleted: FTP 

Deleted: for use in criteria pollutant, fuel economy,

and carbon-related exhaust emission (CREE) 

calculations 

Deleted: test cycle 

Deleted: Equation

Deleted: Eq. 1066.665-3.

Deleted: over the test cycle

Deleted: over the test cycle

Deleted: as given in §1066.1005(f)

Deleted: 000

Deleted: k

Deleted: phase

Deleted: NMOG 

Deleted: phase 

Deleted: Equation

Deleted: Eq. 1066.665-4.

Deleted: old

Deleted: comp

Deleted: composite 

Deleted: phase

Deleted: old

Deleted: comp

Deleted: composite 

Deleted: phase

Deleted: as given in §1066.1005(f)
Example:

eNMHC-FTPct = 0.052 g/mi

VPEtOH = 15.1 %

eNMOG-FTPct     0.052 1.0246 0.0079 15.1 0.0595 g/mi  

(4) You may determine NMOG for the FTP stabilized test interval for either the cold start or hot 

start test for use in fuel economy and CREE calculations based on the NMHC emission rate for 

the test interval and the volume percent of ethanol in the fuel using the following equation

e e VP NMOG-FTPcs-hs NMHC-FTPcs-hs EtOH    1.1135 0.001 

Eq. 1066.665-5

Where:

eNMOG-FTPcs-hs = mass emission rate of NMOG over the FTP stabilized test interval.

eNMHC-FTPcs-hs = mass emission rate of NMHC over the FTP stabilized test interval, calculated 

using ρNMHC-liq.

VPEtOH = volume percentage of ethanol in the test fuel.

(5) You may determine NMOG for the complete FTP hot start test interval for use in fuel 

economy and CREE calculations based on the NMHC emission rate for the test interval and the 

volume percent of ethanol in the fuel using the following equation:

e e VP NMOG-FTPht NMHC-FTPht EtOH    1.0195 0.0031 

Eq. 1066.665-6

Where:

eNMOG-FTPht = mass emission rate of NMOG over the FTP hot start test interval.

eNMHC-FTPht = mass emission rate of NMHC over the FTP hot start test interval, calculated using

ρNMHC-liq.

VPEtOH = volume percentage of ethanol in the test fuel.

(d) You may take the following additional steps when determining fuel economy and CREE 

under 40 CFR part 600:

(1) Calculate NMOG by interval using Eq. 1066.665-3 for individual bag measurements from the 

FTP.

(2) Calculate NMOG for two-bag FTPs using Eq. 1066.665-3 for hybrid-electric vehicles as 

described in 40 CFR 600.114.

(e) We consider NMOG emission values for diesel-fueled vehicles to be equivalent to NMHC 

emission values for all test cycles. Follow paragraph (f) of this section for natural gas fueled 

vehicles with diesel pilot injection.

(f) For all fuels not covered by paragraphs (c) and (e) of this section, manufacturers may propose 

a methodology to calculate NMOG results from measured NMHC emissions. We will approve 

adjustments based on comparative testing that demonstrates how to properly represent NMOG 

based on measured NMHC emissions.

§1066.695 Data requirements.

Record the following information for each test:

(a) Test number.

Deleted: old

Deleted: comp

Deleted: 000

Deleted: k

Deleted: cold or hot 

Deleted: phase

Deleted: NMOG 

Deleted: phase 

Deleted: Eq. 1066.665-5.

Deleted: cold or hot 

Deleted: phase

Deleted: cold or hot 

Deleted: phase

Deleted: as given in §1066.1005(f)

Deleted: phase

Deleted: NMOG 

Deleted: phase 

Deleted: Eq. 1066.665-6.

Deleted: phase

Deleted: phase

Deleted: as given in §1066.1005(f)

Deleted: In addition to the allowance for use of the 

equations in paragraphs (a) and (c) of this section, 

the following provisions apply

Deleted: For determination of fuel economy and 

CREE that use individual FTP phase (bag) emission 

results in 40 CFR part 600, you may c

Deleted: phase

Deleted: For determination of fuel economy and 

CREE for hybrids as described in 40 CFR 600.114-

12, you may c

Deleted: 2

Deleted: For diesel fuel, w

Deleted: e

Deleted: d
(b) A brief description of the test vehicle (or other system/device tested).

(c) Date and time of day for each part of the test sequence.

(d) Test results. Also include a validation of driver accuracy as described in §1066.430(j).

(e) Driver and equipment operators.

(f) Vehicle information as applicable, including identification number, model year, applicable 

emission standards, vehicle model, test group, durability group, engine family, 

evaporative/refueling emission family, basic engine description (including displacement, number 

of cylinders, turbo-/supercharger used, and catalyst type), fuel system (type of fuel injection and 

fuel tank capacity and location), engine code, gross vehicle weight rating, equivalent test weight, 

inertia weight class, actual curb weight at zero miles, actual road load at 50 mph, transmission 

configuration, axle ratio, odometer reading, idle rpm, and drive wheel tire pressure.

(g) Dynamometer identification, inertia weight setting, indicated power absorption setting, and 

records to verify compliance with the driving distance and cycle-validation criteria as calculated 

from measured roll or shaft revolutions.

(h) Analyzer bench identification, analyzer ranges, recordings of analyzer output during zero, 

span, and sample readings.

(i) Associate the following information with the test record: test number, date, vehicle 

identification, vehicle and equipment operators, and identification of the measurements recorded.

(j) Test cell barometric pressure and humidity. You may use a central laboratory barometer if 

the barometric pressure in each test cell is shown to be within ±0.1 % of the barometric pressure 

at the central barometer location.

(k) Records to verify compliance with the ambient temperature requirements throughout the test 

procedure and records of fuel temperatures during the running loss test.

(l) [Reserved]

(m) For CVS systems record, dilution factor for each interval of the exhaust test and the 

following additional information:

(1) CFV and SSV Vmix for each interval of the exhaust test.

(2) PDP. Test measurements required to calculate Vmix for each interval of the exhaust test.

(n) The humidity of the dilution air if you remove H2O from an emission sample before 

measurement.

(o) Temperature of the dilute exhaust mixture and secondary dilution air (in the case of a doubledilution system) at the inlet to the respective gas meter or flow instrumentation used for 

particulate sampling.

(p) The maximum gas temperature over the course of the test within 20 cm upstream or

downstream of the sample media (e.g., filter).

(q) If applicable, the temperature of the heated FID, the gas in the heated sample line, and the 

heated filter.

(r) Gas meter or flow measurement instrumentation readings at the start and end of each test 

interval.

(s) The stabilized pre-test weight and post-test weight of each particulate sample media (e.g., 

filter).

(t) Continuous temperature and humidity of the ambient air in which the particulate sample 

media (e.g., filter).are stabilized.

(u) For vehicles fueled by natural gas, the test fuel composition, including all carbon-containing 

compounds (except CO); e.g. CO2, of the natural gas-fuel used during the test. Record C1 and C2

Deleted: and 

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase
compounds individually. You may record C3 through C5 hydrocarbons together, and you may 

record C6 and heavier hydrocarbon compounds together.

(v) Additional required records for liquefied petroleum gas-fueled vehicles. For vehicles fueled 

by liquefied petroleum gas, the test fuel composition, including all carbon-containing compounds

(except CO); e.g. CO2. Each hydrocarbon compound present, through C4 compounds, shall be 

individually reported. C5 and heavier hydrocarbons may be reported as a group. Record C1 and 

C4 compounds individually. You may record C5 and heavier hydrocarbon compounds together.

Deleted: Record CO and CO2 separately.

Deleted: Record CO and CO2 separately.
Subpart H—Cold-Temperature Test Procedures

§1066.701 Applicability and general provisions.

(a) The procedures of this part 1066 may be used for testing at any ambient temperature. The 

standard-setting part may specify additional provisions for testing conducted at temperatures 

below 20 °C (68 °F). See, for example, 40 CFR part 86, subpart C, for testing related to exhaust 

emission standards and 40 CFR part 600 for calculating fuel economy for light-duty motor 

vehicles. See the standard-setting part to determine if your vehicle is required to meet emission 

standards outside the normal (20 to 30) °C (68 to 86 °F) temperature range.

(b) Do not apply the humidity correction factor in §1066.630(a) for cold-temperature testing.

Deleted: generally apply as described in the 

Deleted: a nominal temperature of –7 °C (20 °F) 

and for testing at 

Deleted: up to
Subpart I—Exhaust Emission Test Procedures for Motor Vehicles 

§1066.801 Applicability and general provisions.

This subpart I specifies how to apply the test procedures of this part for motor vehicles at or 

below 14,000 pounds GVWR, including light-duty vehicles, light-duty trucks, and heavy-duty 

vehicles at or below 14,000 pounds GVWR that are subject to chassis testing for exhaust 

emissions.

(a) Use the procedures detailed in this subpart to measure vehicle emissions over a specified 

drive schedule in conjunction with subpart E of this part. Where the procedures of subpart E of 

this part differ from this subpart I, the provisions in this subpart I take precedence.

(b) Collect samples of every pollutant for which an emission standard applies, unless specified 

otherwise.

(c) This subpart covers the following test procedures:

(1) General driving represented by the Federal Test Procedure (FTP). This procedure is also 

used for measuring evaporative emissions. This may be called the conventional test since it was 

first adopted for the earliest emission standards.

(i) The FTP consists of one Urban Dynamometer Driving Schedule (UDDS) as specified in 

paragraph (a) of Appendix I of 40 CFR part 86, followed by a 10-minute soak with the engine 

off and repeat driving through the first 505 seconds of the UDDS. The UDDS represents about 

7.5 miles of driving in an urban area. FTP measurements consist of a cold-start test and a hotstart test. Engine startup (with all accessories turned off), operation over the initial UDDS, and 

engine shutdown make a complete cold-start test. The hot-start test consists of the first 505 

seconds of the UDDS following the 10-minute soak and a hot-running portion of the UDDS after 

the first 505 seconds. The hot-running portion is generally measured during the cold-start test; 

however, in certain cases, the hot-start test may involve a second full UDDS following the 10-

minute soak. 

(ii) Evaporative testing consists of a preconditioning drive with the UDDS and the FTP driving 

schedule (including exhaust measurement) as described in 40 CFR 86.133-96, followed by 

emission measurements in a sealed enclosure. The running loss test consists of a UDDS, then 

two New York City Cycles as specified in paragraph (f) of Appendix I of 40 CFR part 86, 

followed by another UDDS as described in 40 CFR 86.134-96. The New York City Cycle 

represents about 1.7 miles of driving in a city center.

(iii) Refueling emission testing consists of preconditioning and purge drives using UDDS and 

FTP cycles as described in 40 CFR 86.146 through 86.154.

(2) Supplemental testing that measures the emission effects from more aggressive driving and 

operation with the vehicle’s air conditioner. This Supplemental Federal Test Procedure (SFTP) 

is based on a composite of three different duty cycles. In addition to the FTP measurements, 

vehicles generally operate over the US06 and SC03 driving schedules as specified in paragraphs 

(g) and (h) of Appendix I of 40 CFR part 86, respectively. In the case of heavy-duty vehicles 

above 10,000 pounds GVWR and at or below 14,000 pounds GVWR, SFTP testing involves 

additional driving over the LA-92 driving schedule specified in paragraph (c) of 40 CFR part 86, 

Appendix I, instead of the US06 driving schedule. The US06 cycle represents about 8.0 miles of 

relatively aggressive driving. The SC03 cycle represents about 3.6 miles of urban driving with 

the air conditioner operating. The LA-92 cycle represents approximately 9.8 miles of relatively 

aggressive driving for commercial trucks. 

Comment [CAL6]: Alan, here is my start. This is 

now 801 combined with 803. 

Deleted: driving schedule 

Deleted: s

Deleted: involves 

Deleted: . This includes driving

Deleted: test cycle

Deleted: This additional driving is an essential 

element of the Supplemental Federal Test Procedure 

(SFTP). SFTP testing consists of additional driving 

over the US06 driving schedule and the SC03 

driving schedule specified in paragraphs (g) and (h) 

of Appendix I of 40 CFR part 86, respectively.

Deleted: See §§1066.830 through 1066.833. 
(3) The Highway Fuel Economy Test (HFET). The HFET, specified in Appendix I of 40 CFR 

part 600, is designated to simulate rural and freeway driving with an average speed of 48.6 mph 

and a maximum speed of 60.0 mph. The cycle is 10.2 miles long.

(4) Cold-temperature testing. Cold-temperature standards apply for CO and NMHC emissions 

when vehicles operate over the FTP at a nominal temperature of 20 °F.

(5) Air conditioning credits for greenhouse gas standards. Vehicles operate over repeat runs of 

the AC17 test sequence to allow for calculating credits as part of demonstrating compliance with 

CO2 emission standards. The AC17 test sequence consists of a UDDS preconditioning drive, 

followed by emission measurements over the SC03 and HFET driving schedules.

(d) Starting in model year 2022, speed tolerances and cycle-validation criteria apply as specified 

in 40 CFR part 1066, subpart E; however, for road load power determination in §1066.810, 

vehicle preconditioning, fuel dispensing spitback in 40 CFR 86.146, and canister purging in 40 

CFR 86.153-98(d), the upper and lower speed tolerances are ±4.0 mph. Up to three additional 

occurrences of speed variations greater than the tolerance are acceptable for road load power 

determination in §1066.810 and canister purging in 40 CFR 86.153-98(d), provided they occur 

for less than 15 seconds on any occasion, and are clearly documented as to the time and speed at 

that point of the driving schedule.

§1066.810 Road load power, test weight, and inertia weight class determination.

(a) Simulate a vehicle’s test weight on the dynamometer using the appropriate equivalent test 

weight shown in Table 1 of this section. Equivalent test weights are established according to 

each vehicle’s test weight basis, as described in paragraph (b) of this section. Table 1 also 

specifies the inertia weight class corresponding to each equivalent test weight; the inertia weight 

class allows for grouping vehicles with a range of equivalent test weights. Table 1 follows:

Table 1 of §1066.810–Equivalent test weights (pounds)

Test weight basis Equivalent test weight Inertia weight class

Up to 1062 1000 1000

1063 to 1187 1125 1000

1188 to 1312 1250 1250

1313 to 1437 1375 1250

1438 to 1562 1500 1500

1563 to 1687 1625 1500

1688 to 1812 1750 1750

1813 to 1937 1875 1750

1938 to 2062 2000 2000

2063 to 2187 2125 2000

2188 to 2312 2250 2250

2313 to 2437 2375 2250

2438 to 2562 2500 2500

2563 to 2687 2625 2500

2688 to 2812 2750 2750

2813 to 2937 2875 2750

Deleted: SC03.¶

Deleted: (4) AC17.¶

(5) HFET.¶

(6) AC idle.¶

(7) LA-92.¶

Deleted: ±2.0 m/s (

Deleted: )
2938 to 3062 3000 3000

3063 to 3187 3125 3000

3188 to 3312 3250 3000

3313 to 3437 3375 3500

3438 to 3562 3500 3500

3563 to 3687 3625 3500

3688 to 3812 3750 3500

3813 to 3937 3875 4000

3938 to 4125 4000 4000

4126 to 4375 4250 4000

4376 to 4625 4500 4500

4626 to 4875 4750 4500

4876 to 5125 5000 5000

5126 to 5375 5250 5000

5376 to 5750 5500 5500

5751 to 6250 6000 6000

6251 to 6750 6500 6500

6751 to 7250 7000 7000

7251 to 7750 7500 7500

7751 to 8250 8000 8000

8251 to 8750 8500 8500

8751 to 9250 9000 9000

9251 to 9750 9500 9500

9751 to 10250 10000 10000

10251 to 10750 10500 10500

10751 to 11250 11000 11000

11251 to 11750 11500 11500

11751 to 12250 12000 12000

12251 to 12750 12500 12500

12751 to 13250 13000 13000

13251 to 13750 13500 13500

13751 to 14000 14000 14000

(b) The test weight basis for non-MDPV heavy-duty vehicles is adjusted loaded vehicle weight, 

as defined in 40 CFR 86.1803. For all other vehicles, the test weight basis for establishing 

equivalent test weight is loaded vehicle weight, as defined in 40 CFR 86.1803.

(c) For each test vehicle subject to FTP and SFTP standards, determine road load forces at 

speeds between 10 and 70 miles per hour. The road load force must represent vehicle operation 

on a smooth level road with no wind or calm winds, no precipitation, an ambient temperature of 

approximately 20 °C (68 °F), and atmospheric pressure of 98.21 kPa. You may extrapolate road 

load force for speeds below 10 mph.

§1066.812 Test sequence; general requirements.

Deleted: The test weight basis for establishing 

equivalent test weight is loaded vehicle weight, as 

defined in 40 CFR 86.1803, with the following 

exceptions:¶

(1) For heavy light-duty trucks (LDT3 and LDT4), 

test weight basis is adjusted loaded vehicle weight 

for emission tests and loaded vehicle weight for fuel 

economy tests. Manufacturers may choose instead 

to perform fuel economy tests at adjusted loaded 

vehicle weight. Weight terms are defined in 40 CFR 

86.1803. ¶

(2) For MDPVs and heavy-duty vehicles, test weight 

basis is adjusted loaded vehicle weight.

Deleted: during 

Deleted: at least 

Deleted: (d) We may approve an alternate test 

cycle and cycle-validation criteria for vehicles that 

do not have enough power to follow the specified 

driving trace. The alternate driving specifications 

must be based on making best efforts to maintain 

acceleration and speed to follow the specified test 

cycle. We must approve these alternate driving 

specifications before you perform this testing.¶
(a) The following provisions apply for all testing:

(1) Ambient temperatures encountered by the test vehicle must be (20 to 30) °C, unless 

otherwise specified. For vehicle soaking steps, the soak period may be interrupted once for up to 

10 minutes to transport the vehicle from one soak area to another, as long as the ambient 

temperature experienced by the vehicle is never below 20 °C. The temperatures monitored 

during testing must be representative of those experienced by the test vehicle.

(2) Use good engineering judgment to ensure that the vehicle remains approximately level 

throughout testing to prevent abnormal fuel distribution.

(3) If a test is void after collecting emission data from previous test segments, the test may be 

repeated to collect only those data points needed to complete emission measurements. You may 

combine emission measurements from different test runs to demonstrate compliance with 

emission standards. 

(b) FTP testing consists of a sequence of steps for measuring both exhaust and evaporative 

emissions. Evaporative testing involves both a two-day test sequence and a three-day test 

sequence as shown in Figure 1 of this section. For vehicles with no evaporative canister, this 

defaults to a single test sequence for measuring FTP exhaust emissions. Evaporative test 

procedures are described in detail in 40 CFR part 86, subpart B.

(c) Test procedures for onboard refueling vapor recovery are described in 40 CFR 86.150 

through 86.157. This testing is also integral with the FTP test sequence. Fuel spitback testing is 

conducted as a stand-alone test as described in 40 CFR 86.146.

(d) SFTP testing is performed as described in §§1066.830 through 1066.832. This testing may be 

performed in any sequence that follows the preconditioning protocol described in §1066.831.

Figure 1 of §1066.812–Federal test procedure test sequence. 

Comment [CAL7]: Alan, please rearrange this 

paragraph. 

Deleted: 16
Fuel drain and fill

Vehicle Soak

Preconditioning drive

1 hour MAX

Fuel drain and fill

Precondition canister Precondition canister

Cold start exhaust test Cold start exhaust test

10 minutes 10 minutes

Hot start exhaust test Hot start exhaust test

1-5 hours 7 minutes MAX

Running loss test Hot soak test

7 minutes max 68 - 86 °F ambient

Hot soak test

90-100 °F ambient Vehicle soak

Vehicle soak Diurnal emission test

2 heat builds in 48 hours

Diurnal emission test

3 heat builds in 72 hours

6-36 hours

12-36 hours

1 hour

6-36 hours

1 hour

6-36 hours

Start

End

End

Diesel 

Only

§1066.814 Vehicle preparation.

(a) For vehicles subject to running loss testing, prepare the fuel tank(s) for recording the 

temperature of the test fuel, as described in 40 CFR 86.107–98(e).

(b) Provide additional fittings and adapters, as required, to accommodate a fuel drain at the 

lowest point possible in the tank(s) as installed on the vehicle.

(c) For preconditioning that involves loading evaporative emission canister with butane, provide 

valving or other means as necessary to allow purging and loading of the canister.

(d) For vehicles to be tested for running loss emissions according to 40 CFR 86.134-96, prepare 

the fuel tank for measuring and recording the temperature and pressure of the fuel tank as 

specified in 40 CFR 86.107–98(e) and (f). Vapor temperature measurement is optional during 

the running loss test. If vapor temperature is not measured, fuel tank pressure need not be 

measured.

(e) For vehicles to be tested for running loss emissions according to 40 CFR 86.134-96, prepare 

the exhaust system by sealing or plugging all detectable sources of exhaust gas leaks. Inspect or 

test the exhaust system to ensure that no detectable exhaust hydrocarbons are emitted into the 

running loss enclosure during testing.

(f) The following provisions apply for preconditioning steps to reduce nonfuel emissions to 

normal vehicle background levels for vehicles subject to Tier 3 evaporative emission standards 

under 40 CFR 86.1813:

(1) Manufacturers must notify us in advance if they plan to perform such preconditioning. This 

notice must include a detailed description of the intended procedures and any measurements or 
thresholds for determining when stabilization is complete. Manufacturers need not repeat this 

notification for additional vehicle testing in the same or later model years as long as the 

preconditioning practice conforms to these procedures.

(2) Manufacturers may precondition a vehicle as described in paragraph (f)(1) of this section 

only within 12 months after the vehicle’s original date of manufacture, except they may remove 

the spare tire for any testing.

§1066.820 Exhaust emission test procedures for FTP testing.

(a) General. The dynamometer run consists a cold start testing and hot start testing. Cold start 

testing begins after a 12 to 36 hour soak according to the provisions of 40 CFR 86.132. Hot 

start testing begins 10 minutes after the end of the cold start UDDS. See §1066.801 for further 

information on the driving schedules. 

(b) PM sampling options. You may collect PM using any of the procedures specified in 

paragraphs (b)(1) through (5) of this section, taking into account the FTP composite emission 

calculations in §1066.822. Testing must meet the requirements related to filter face velocity as 

described in 40 CFR 1065.170(c)(1)(vi), except where flow weighting is allowed. If a procedure 

is chosen that allows flow weighting, set the filter face velocity of weighting targets of 1.0 to 

meet the requirements of 40 CFR 1065.170(c)(1)(vi) and allow filter face velocity to decrease as 

a percentage of the weighting factor for weighting factors that are less than 1.0. Use the 

appropriate DF equations in §1066.620 to show that you meet the dilution factor requirements of 

§1066.110(b)(2)(iii)(B).

(1) You may collect a separate PM sample for each test interval of the FTP. 

(2) You may collect PM on one filter over the cold start UDDS and on a separate filter over the 

hot start UDDS.

(3) You may collect PM on one filter over the cold start UDDS (bags 1 and 2) and on a separate 

filter over the 867 seconds of the stabilized portion of the cold start UDDS and the first 505 

seconds of the hot start UDDS (bags 2 and 3). Note that this option involves duplicate 

measurements during the stabilized portion of the cold start UDDS.

(4) You may collect PM on a single filter over the cold start UDDS and the first 505 seconds of 

the hot start UDDS. If you choose this option, you must adjust your sampling system flow rate 

to weight the filter face velocity over the three intervals of the FTP, based on weighting targets 

of 0.43 for bag 1, 1.0 for bag 2, and 0.57 for bag 3.

(5) You may collect PM on a single filter over the cold start UDDS and the full hot start UDDS. 

If you choose this option, you must adjust your sampling system flow rate to weight the filter 

face velocity, based on weighting targets of 0.754 for the cold start UDDS and 1.0 for the hot 

start UDDS.

(c) Test sequence. Perform FTP testing in the following sequence:

(1) Start sampling and recording simultaneously with starting the vehicle.

(2) Fifteen seconds after the engine starts, place the transmission in gear.

(3) Twenty seconds after the engine starts, begin the initial vehicle acceleration of the driving 

schedule.

(4) Operate the vehicle over the remainder of the UDDS as described in §1066.801.

(5) At the end of the deceleration scheduled to occur 505 seconds into the cold start UDDS, 

simultaneously switch all the sample flows from the cold start transient interval to the stabilized 

interval, stopping all cold start transient interval sampling and recording, including background 

Deleted: g

Deleted: 4

Deleted: , instead of collecting a separate PM 

sample for each phase of the FTP. In all cases, t

Deleted: 1

Deleted: phase

Deleted: 2

Deleted: (3) You may collect PM on one filter 

over the cold start UDDS and on a separate filter 

over the hot start UDDS.¶

(4) You may collect PM on one filter over the cold 

start UDDS (bags 1 and 2) and on a separate filter 

over the 867 seconds of the stabilized portion of the 

cold start UDDS and the first 505 seconds of the hot 

start UDDS (bags 2 and 3) Note that this option 

involves duplicate measurements during the 

stabilized portion of the cold start UDDS.¶

Deleted: phase

Deleted: phase

Deleted: phase
sampling. Reset integrating devices for the stabilized interval and indicate the end of the cold 

start interval in the recorded data.

(6) Turn the engine off 2 seconds after the end of the last deceleration in the stabilized interval

(1,369 seconds after the start of the test cycle).

(7) Five seconds after the engine stops running, stop all stabilized interval sampling and 

recording, including background sampling, stop integrating devices for the stabilized interval,

and indicate the end of the stabilized interval in the recorded data. Note that the 5 second delay 

is intended to approximate sampling system transport time.

(8) Take the following steps for the hot start test:

(i) Repeat the steps in paragraphs (c)(1) through (3) of this section. Operate the vehicle over 

the first 505 seconds of the UDDS as described in §1066.803. Begin hot start testing (9 to 11) 

minutes after the end of the sample period for the cold start UDDS. 

(ii) At the end of the deceleration scheduled to occur 505 seconds into the hot start UDDS, turn 

off the engine and simultaneously stop all hot start sampling and recording, including 

background sampling, and integrating devices. As described in §1066.822, hot start testing may 

in some cases involve driving over the full UDDS as for cold start testing.

(9) This completes the procedures for measuring FTP exhaust emissions. See 40 CFR part 86, 

subpart B, to continue measurement procedures for evaporative or refueling tests. 

§1066.822 FTP exhaust emission composite calculations.

(a) Determine the mass of exhaust emissions of each pollutant for each interval of FTP testing as 

described in §1066.610.

(b) Calculate the final reported test results as a mass-weighted value, e[emission]-FTPcomp, in 

grams/mile using the following equation:

c h

[emission]-FTPcomp

ct cs ht hs

0.43 0.57 m m e DD DD

  

         

 Eq. 1066.822-1

Where:

mc = the combined mass emissions determined from the cold start UDDS (generally known as 

bags 1 and 2), in grams.

Dct = the measured driving distance from the transient portion of the cold start test (bag 1), in 

miles.

Dcs = the measured driving distance from the stabilized portion of the cold start test (bag 2), as 

applicable, in miles.

mh = the combined mass emissions determined from the hot start UDDS in grams. This is the 

hot stabilized portion from either the first or second UDDS, if applicable (bag 2 or bag 4), in 

addition to the hot transient portion (bag 3). See paragraph (d) of this section for special 

provisions that apply for PM measurement.

Dht = the measured driving distance from the transient portion of the hot start test (bag 3), in 

miles.

Dhs = the measured driving distance from the stabilized portion of the hot start test (bag 4), as 

applicable, in miles. Set Dhs = Dcs for testing where the hot stabilized portion of the UDDS is not 

run.

(c) For all pollutants, mass emissions for the cold start UDDS may alternatively be collected 

separately for the cold start transient portion and the cold stabilized portion, then added together 

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase
for a single cold start mass, mc. Similarly, mass emissions for the hot start UDDS may 

alternatively be collected separately for the hot start transient portion, then added together with 

the cold stabilized portion or hot stabilized portion for a single hot start mass, mh.

(d) Calculate the final reported test results for PM as a mass-weighted value, ePM-FTPcomp, in 

grams/mile as follows:

(1) Use the following equation for PM measured as described in §1066.820(b)(1):

   PM

PM-FTPcomp

ct cs ht 0.43 0.57

m e D D D    

 Eq. 1066.822-2

Where:

mPM = PM mass emissions determined from the test consisting of the cold start UDDS and the 

first 505 seconds of the hot-start UDDS (bags 1, 2, and 3), in grams per test interval, as 

calculated using Eq. 1066.610-3.

(2) Use the following equation for PM measured as described in §1066.820(b)(2):

   PM

PM-FTPcomp

ct cs ht hs 0.43 0.57

m e D D DD   

 Eq. 1066.822-3

Where:

mPM = PM mass emissions determined from the test consisting of the cold start UDDS and the 

hot start UDDS (bags 1, 2, 3, and 4), in grams per test interval, as calculated using Eq. 1066.610-

4.

(3) Use the following equation for PM measured as described in §1066.820(b)(3):

PM-cUDDS PM-hUDDS

PM-FTPcomp

ct cs ht hs

0.43 0.57 m m e DD DD

  

         

 Eq. 1066.822-4

Where:

mPM-cUDDS = PM mass emissions determined from the test consisting of the cold start UDDS

(bags 1 and 2), in grams per test interval, as calculated using Eq. 1066.610-2.

mPM-hUDDS = PM mass emissions determined from the test consisting of the hot start UDDS (bags 

3 and 4), in grams per test interval, as calculated using Eq. 1066.610-2.

(4) For PM measured as described in §1066.820(b)(4), calculate PM emissions as described in 

paragraph (d)(3) of this section, except that mPM-hUDDS is the PM mass emissions determined 

from the stabilized portion of the cold start UDDS and the first 505 seconds of the hot start 

UDDS (bags 2 and 3).

§1066.830 Supplemental Federal Test Procedures; overview.

The procedures described in §§1066.831 through 1066.834 describe the Supplemental Federal 

Test Procedure (SFTP). This testing applies for all vehicles subject to the SFTP standards in 40 

CFR part 86, subpart S. The SFTP test procedure consists of two separable test elements: A 

sequence of vehicle operation with more aggressive driving; and a sequence of vehicle operation 

that includes the impact of the vehicle’s air conditioner. 

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase
(a) Collect samples of every pollutant for which an emission standard applies, unless specified 

otherwise.

(b) The aggressive-driving procedure consists of preconditioning the engine to a hot stabilized 

condition, after which the vehicle starts operating over the test cycle. For most vehicles, the 

US06 test cycle applies. Some heavy-duty vehicles operate over a subset of the US06 test cycle, 

or over the LA-92 test cycle.

(c) The SC03 test procedure in §1066.832 is designed to determine gaseous exhaust emissions 

while simulating an urban trip on a hot summer day. The full test consists of an engine key-off 

for 10 minutes following the preconditioning steps, an engine start, and operation over the SC03 

test cycle. The provisions of 40 CFR part 86, subpart B, and 40 CFR part 600 waive SC03 

testing for some vehicles; in those cases, SFTP composite emissions are calculated by adjusting 

the weighting calculation. 

(d) The SFTP standard applies as a composite representing the constituent test cycles. The 

emission results from the aggressive driving test element (§1066.831), the air conditioning test 

element (§1066.832), and the FTP test element (§1066.812 (a) through (d) and (f)) are analyzed 

according to the calculation methodology and compared to the applicable SFTP emission 

standards in 40 CFR part 86, subpart S.

(e) The SFTP elements may be run in any sequence that maintains the applicable preconditioning 

steps specified in §86.816.

§1066.831 Exhaust emission test procedures for aggressive driving.

(a) Perform testing as described in this section using the US06 cycle or the LA-92 cycle. The 

US06 cycle can be divided into two test intervals—the US06 City cycle comprises the combined 

portions of the cycle from 1 to 130 seconds and from 495 to 596 seconds, and the US06 

Highway cycle comprises the portion of the cycle between 130 and 495 seconds. See §1066.801 

for further information on the driving schedules. Collect samples of every pollutant for which an 

emission standard applies, unless specified otherwise.

(b) Prepare test vehicles as described in §1066.814 for the FTP test element. Take the following 

steps to precondition vehicles for testing under this section:

(1) Drain and refill the vehicle’s fuel tank(s) in any of the following cases:

(i) For testing unrelated to FTP or HFET testing.

(ii) For a test element that starts more than 72 hours after the most recent FTP or HFET 

measurement (with or without evaporative emission measurements).

(iii) For testing in which the test vehicle has not remained in an area where ambient temperatures 

were within the range specified for testing since the previous FTP or HFET.

(2) Take the following steps to precondition vehicles before the aggressive driving test element:

(i) Keep ambient temperatures within the ranges specified for test measurements throughout the 

preconditioning sequence.

(ii) Push or drive the test vehicle onto the dynamometer.

(iii) Operate the test vehicle as needed to prepare it for testing and to perform practice runs (for 

the driver or for sampling equipment). For our testing, we will generally operate the vehicle over 

the same cycle that will be used for testing in §86.831. You may ask us to perform vehicle 

preconditioning in a certain way to address fuel effects on adaptive memory systems or other 

factors. Do not measure emissions during the preconditioning drive.

(iv) Operate the test vehicle one time over one of the driving schedules specified in this 

paragraph (b)(3). You may ask us to use a particular preconditioning driving schedule if that is 

Deleted: in §1066.837 

Deleted: described in paragraph (g) of 40 CFR part 

86, appendix I 

Deleted: as specified in paragraph (c) of 40 CFR 

part 86, appendix I

Deleted: phase

Deleted: condition and
related to fuel effects on adaptive memory systems. Choose from the following driving 

schedules:

(A) The first 505 seconds of the UDDS (generally known as bag 1)

(B) The last 866 seconds of the UDDS (generally known as bag 2).

(C) The highway fuel economy test cycle.

(D) US06 cycle or, for heavy-duty vehicles above 10,000 pounds GVWR, just the highway 

portion of the US06 cycle. 

(E) The SC03 test cycle.

(F) The LA-92 test cycle. 

(4) Allow the vehicle to idle for (1 to 2) minutes. This leads directly into the test measurements 

described in §1066.831,

(c) Take the following steps to precondition vehicles before the air conditioning test element:

(1) Keep the vehicle in an environment meeting the conditions described in §1066.833 

throughout the preconditioning sequence. 

(2) Push or drive the test vehicle onto the dynamometer.

(3) Operate the test vehicle one time over the first 505 seconds of the UDDS (bag 1), the last 867 

seconds of the UDDS (bag 2), or the SC03 test cycle. If the air conditioning test sequence starts 

more than 2 hours after a different exhaust emission test, you may instead operate the vehicle 

over the full UDDS.

(4) Following the preconditioning drive, turn off the test vehicle and the vehicle cooling fan(s) 

and allow the vehicle to soak for (9 to 11) minutes. This leads directly into the test 

measurements described in §1066.832.

(d) For testing based on the full US06 cycle, you may collect emissions as a single test interval, 

or you may collect emissions from city and highway test intervals separately (see 40 CFR part 

600). Take the following steps for separate city and highway measurements:

(1) At 130 seconds, simultaneously stop all “US06 City”, and start all “US06 Highway” 

sampling, recording, and integrating (including background sampling). At 136 seconds (before 

the acceleration), record the measured dynamometer roll revolutions.

(2) At 495 seconds, simultaneously stop all “US06 Highway”, and start all “US06 City” 

sampling, recording, and integrating (including background sampling). At 500 seconds (before 

the acceleration), record the measured dynamometer roll revolutions.

(3) Except as specified in paragraph (c)(4) of this section, treat the emissions from the two 

discrete portions of city driving as a single sample.

(4) If you collect gaseous emissions over two test intervals, you may collect PM as a single test 

interval over the full US06. If you do, then calculate a composite dilution factor based on city 

and highway emissions, using equation 1066.620-4, to show that you meet the dilution factor 

requirements of §1066.110(b)(2)(iii)(B). 

(e) For diesel fueled vehicles, measure THC emissions on a continuous basis as described in 40 

CFR part 1065. For separate city and highway measurements as described in paragraph (c) of 

this section, perform separate calculations for each portion of the test cycle.

(f) The provisions of §§1066.410 through 1066.430 apply, subject to the following exceptions 

and additional provisions:

(1) Following the preconditioning specified in §1066.830, place the vehicle in gear and 

simultaneously start sampling and recording. Begin the first acceleration 5 seconds after placing 

the vehicle in gear.

(2) Operate the vehicle over one of the following test cycles:

Deleted: c

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: c

Deleted: d
(i) For heavy-duty vehicles above 10,000 pounds GVWR, operate the vehicle over the LA-92 

driving schedule.

(ii) Heavy-duty vehicles above 8,500 pounds GVWR and at or below 10,000 pounds GVWR 

may be certified using only the highway portion of the US06 driving schedule. See 40 CFR 

86.1816. 

(iii) In all other cases, operate the vehicle over the full US06 driving schedule.

(3) Turn the engine off 2 seconds before the end of the driving schedule. Five seconds after the 

engine stops running, stop all sampling and recording (including background) and stop 

integrating devices. Indicate the end of the test cycle in the recorded data.

(4) Correct calculated NOx emissions tests as described in §1066.630(a)(1).

§1066.832 Exhaust emission test procedure for SC03 emissions.

(a) Perform testing as described in this section using the SC03 cycle. See §1066.801 for further 

information on the driving schedules. Precondition the vehicle in accordance with §1066.831 of 

this subpart to bring the vehicle to a warmed-up stabilized condition. Section 1066.833 discusses 

the minimum facility requirements and corresponding control tolerances for air conditioning 

ambient test conditions.

(b) The provisions of §§1066.410 through 1066.430 apply, subject to the following exceptions 

and additional provisions: 

(1) You may position additional cooling fans to provide sufficient air for vehicle cooling if the 

vehicle has a rear-mounted engine or if the fan configuration described in §1066.410(b)(1)(iv) is 

not adequate. The additional cooling fans may have a total capacity up to 2.50 m3/s; however, 

you may ask us to approve a greater fan capacity under 40 CFR 1065.10(c)(1) by demonstrating 

that the greater airflow represents in-use operation in a way that has a meaningful effect on 

emissions. 

(2) Close all the vehicle’s windows before testing.

(3) The test cell and equipment must meet the specifications in paragraph (c) of this section. 

Measure and control ambient conditions as specified in paragraph (d) of this section.

(4) Set the vehicle’s air conditioning controls by selecting A/C mode and “maximum”, setting 

airflow to “recirculate” (if so equipped), selecting the highest fan setting, and turning the A/C 

Temperature to full cool (or 72 °F for automatic systems). Turn the controls to the “on” position 

before testing so the air conditioning system is active whenever the engine is running.

(5) Initiate data logging, sampling of exhaust gases, and integrating measured values before 

starting the engine.

(6) Simultaneously start the engine and initiate the driver’s trace. Place the vehicle in gear 15 

seconds after the engine starts to prepare for the initial acceleration. Follow the SC03 driving 

schedule. 

(7) Turn the engine off 2 seconds before the end of the driving schedule. Five seconds after the 

engine stops running, stop all sampling and recording (including background) and stop 

integrating devices, indicating the end of the test cycle in the recorded data. Note that the 5 

second delay is intended to approximate sampling system transport time.

(8) Correct calculated NOx emissions as described in §1066.630(a)(2).

(c) Test cell and equipment requirements. (1) Minimum test cell size. The test cell must be at 

least 20 feet wide, 40 feet long, and 10 feet high, unless we approve the use of a smaller test cell. 

We will approve this only if you demonstrate that the smaller test cell is capable of meeting all 

the requirements of this section.

Deleted: as specified in paragraph (c) of 40 CFR 

part 86, appendix I

Deleted: ,i

Deleted: ing

Deleted: as described in appendix I, paragraph (h), 

of 40 CFR part 86

Deleted: 1066.816

Deleted: simply 

Deleted: Keep the vehicle in an environment 

meeting the conditions described in §1066.833 

throughout testing. 
(2) Vehicle frontal air flow. Verify that the test configuration meets the requirements of 

§1066.410(b)(1)(iv) before each test.

(d) Test cell ambient conditions. (1) Ambient air temperature. Measure and record ambient air 

temperature in the test cell at least once every 30 seconds during the sampling period. Control 

ambient air temperature during emission sampling to a tolerance of 95 ±5 °F throughout the test 

and (93 to 97) °F on average. 

(2) Ambient humidity. Measure and record ambient humidity in the test cell at least once every 

30 seconds during the sampling period. Control ambient air temperature during emission 

sampling as described in §1066.425(d).

(3) Vehicle preconditioning. Use good engineering judgment to demonstrate that you meet the 

specified instantaneous temperature and humidity tolerances in paragraphs (c)(1) and (2) of this 

section at all times before and between emission measurements, except that you may exclude up 

to 3 minutes over the course of a test sequence to account for vehicle transport and other actions 

to prepare for testing.

(4) Solar heat load. Simulate solar heating as follows:

(i) You may use a metal halide lamp, a sodium lamp, or a quartz halogen lamp with dichroic 

mirrors as a radiant energy emitter. We may also approve the use of a different type of radiant 

energy emitter if you demonstrate that it meets the requirements of this section. 

(ii) We recommend achieving radiant heating with spectral distribution characteristics as 

described in the following table:

Table 1 of §1066.833–Recommended Spectral Distribution

Band width (nm) Percent of total spectrum

Lower limit (%) Upper limit (%)

<320a — 0

320–400 0 7

400–780 45 55

>780 35 53

a

Note that you may need to filter the UV region between 280 and 320 nm.

(iii) Determine radiant energy intensity experienced by the vehicle as the average value between 

two measurements along the vehicle’s centerline, one at the base of the windshield and the other 

at the bottom of the rear window (or equivalent location for vehicles without a rear window). 

This value must be 850 ±45 W/m2. Instruments for measuring radiant energy intensity must 

meet the following minimum specifications:

(A) Sensitivity of 9 microvolts per watt/m2.

(B) Response time of 1 second.

(C) Linearity of ± 0.5 %.

(D) Cosine of ± 1 % from normalization 0–70 degree zenith angle. 

(iv) Check the uniformity of radiant energy intensity at least every 500 hours of emitter usage or 

every 6 months, whichever is shorter, and after any major modifications affecting the solar 

simulation. Determine uniformity by measuring radiant energy intensity as described in 

paragraph (d)(4)(iii) of this section at each point of a 0.5 m grid over the vehicle’s full footprint, 

including the edges of the footprint, at an elevation 1 m above the floor. Measured values of

radiant energy intensity must be between (732 and 978) W/m2 at all points.
§1066.835 AC17 air conditioning efficiency test procedure.

(a) Overview. This section describes a procedure for measuring the net impact of air conditioner 

operation. See 40 CFR 86.1868 for provisions describing how to use these procedures to 

calculate credits and otherwise comply with emission standards. 

(b) Test cell. Operate the vehicle in a test cell meeting the specifications described in §86.832(c). 

You may add airflow up to at a maximum of 4 miles per hour during engine idling and when the 

engine is off if that is needed to meet ambient temperature or humidity requirements. Also, You 

may position additional cooling fans to provide sufficient air for vehicle cooling if the vehicle 

has a rear-mounted engine or if the fan configuration described in §1066.410(b)(1)(iv) is not 

adequate. The additional cooling fans may have a total capacity up to 2.50 m3/s; however, you 

may ask us to approve a greater fan capacity under 40 CFR 1065.10(c)(1) by demonstrating that 

the greater airflow represents in-use operation in a way that has a meaningful effect on emissions.

(c) Ambient conditions. Measure and control ambient conditions as specified in §86.832(d), 

except that during emission sampling you must target 77 °F throughout the test, your test is not 

valid if the average value is < 75 °F or > 79 °F, and your instantaneous temperature must be (72

to 82) °F. Also, solar heating is disabled for certain test intervals as described in this section.

(d) Interior air temperature measurement. Measure and record interior air temperature in the test 

vehicle at least once every 5 seconds during the sampling period. Measure temperature at the 

outlet of the center-most duct on the dashboard and approximately 30 mm behind the driver and 

passenger’s headrests. 

(e) Air conditioning system settings. When vehicle air conditioning is required, set the vehicle’s 

air conditioning controls as follows: 

(1) For automatic systems, set the temperature control to 72 °F.

(2) For manual systems, select A/C mode and “maximum”, set airflow to “recirculate” (if so 

equipped), and select the highest fan setting. During the first idle period of the SC03 drive cycle 

(between 186 and 204 seconds), reduce the fan speed to nominally 50 % of maximum fan speed, 

set airflow to “fresh air” (if so equipped), and adjust the temperature setting to target a 

temperature of 55° F at dashboard air outlet.

(f) Test procedure. Follow the procedures specified in §§1066.410 through 1066.430, subject to 

the following exceptions and additional provisions: 

(1) Prepare the vehicle for testing according to 40 CFR 86.132(a) through (g), concluding with a 

12 to 36 hour soak.

(2) Open all the vehicle’s windows and operate the vehicle over a preconditioning UDDS with 

no solar heating and with the air conditioning off. At the end of the preconditioning drive, turn 

off the test vehicle and all cooling fans. 

(3) Turn on solar heating within one minute after turning off the engine. Once the solar energy 

intensity reaches 805 W/m2, let the vehicle soak for 30 ±1 minutes. You may rely on prior 

measurements to start the soak period after a defined period of warming up the solar heat load 

instead of measuring solar energy intensity. Close all of the vehicle’s windows at the start of the 

soak period; ensure that the windows are adequately closed where instrumentation and wiring 

pass through to the interior.

(4) Initiate data logging, sampling of exhaust gases, and integrating measured values before 

starting the engine. Start the engine with the air conditioning system already turned on. Operate 

the vehicle over the SC03 driving schedule. Initiate the driver’s trace when the engine starts. 

Fifteen seconds after the engine starts, place the vehicle in gear and operate the vehicle over the 
rest of the driving schedule. At the end of the driving schedule, simultaneously switch all the 

sampling, recording, and integrating from SC03 to HFET, including background sampling. 

Indicate the end of the test cycle in the recorded data. Record the measured dynamometer roll 

revolutions corresponding to the SC03 drive schedule.

(5) Directly following the SC03 drive, operate the vehicle over the HFET driving schedule. Turn 

the vehicle off at the end of the driving schedule and simultaneously stop all sampling, recording, 

and integrating, including background sampling. Indicate the end of the test cycle in the 

recorded data. Record the measured dynamometer roll revolutions corresponding to the HFET 

drive schedule. Turn off the solar heating.

(6) Allow the vehicle to remain on the dynamometer for (10 to 15) minutes after emission 

sampling has concluded. Repeat the testing described in paragraphs (f)(1) through (5) of this 

section, but leave the vehicle’s windows open and turn off the vehicle’s air conditioner and the 

solar heating throughout the test run.

(g) Calculations. (1) Determine the mass of exhaust emissions of each pollutant for each interval

of AC17 testing as described in §1066.610.

(2) Calculate the final reported mass-weighted emissions of CO2, e[CO2]-AC17comp, representing the 

average of the SC03 and HFET emissions, in grams/mile using the following equation:

SC03 HFET

CO2-AC17comp

SC03 HFET

0.5 0.5 m m e D D

   

         

 Eq. 1066.835-1

Where:

mSC03 = Mass emissions from the SC03 test interval, in grams.

mHFET = Mass emissions from the HFET test interval, in grams.

DSC03 = The measured driving distance during the SC03 test interval, in miles.

DHFET = The measured driving distance during the HFET test interval, in miles.

(h) Recordkeeping. In addition to the information specified in §1066.695, you must record the 

following information for each vehicle tested: vehicle class, model type, carline, curb weight, 

engine displacement, transmission class and configuration, interior volume, climate control 

system type and characteristics, refrigerant used, compressor type, and evaporator/condenser 

characteristics.

§1066.839 Highway fuel economy test procedure.

This section provides the test procedure for the highway fuel economy test (HFET). This test 

involves fuel economy and emission sampling for certain vehicles as described in 40 CFR part 

86, subpart S, and in 40 CFR part 600. See §1066.801 for further information on the driving 

schedules. To perform a test, follow the procedures specified in §§1066.410 through 1066.430, 

subject to the following exceptions and additional provisions: 

(a) Perform the HFET immediately following the FTP when this is practical. If the HFET 

procedure starts more than 3 hours after an FTP (including evaporative measurements, if 

applicable), operate it over one UDDS cycle to precondition the vehicle. We may approve 

additional preconditioning in unusual circumstances.

(b) Operate the vehicle over the Highway Fuel Economy Driving Schedule for preconditioning. 

Allow the vehicle to idle for 15 seconds (with the vehicle in gear), then start a repeat run of the 

Highway Fuel Economy Driving Schedule and simultaneously start sampling and recording. 

Deleted: (a) We will select vehicle configurations 

with a certain test weight from your fleet based on 

projected sales volumes. 

Comment [CAL8]: Make sure this deleted 

paragraph is retained in part 600. 

Deleted: ¶

Deleted: b

Deleted: c
(c) Turn the engine off at 765 seconds, stop integrating devices and all sampling and recording, 

including background. Indicate the end of the test cycle in the recorded data.

§1066.840 Fuel storage system leak test procedure.

(a) Scope. Verify that there are no significant leaks in your fuel storage system using the leak 

test described in this section. Perform this check as required in the standard-setting part.

(b) Measurement principles. A leak may be detected by measuring pressure, temperature, and 

flow to calculate an equivalent orifice diameter for the system. Use good engineering judgment 

to develop and implement leak test equipment. Your leak test equipment must meet the 

following requirements:

(1) Pressure, temperature, and flow sensors must be calibrated with NIST-traceable standards. 

(2) Correct flow measurements to standard temperature and pressure of 20 °C and 101.325 kPa.

(3) Leak test equipment must have the ability to pressurize fuel storage systems to 4.1 kPa and 

have an internal leak rate of less than 0.2 slpm.

(4) You must be able to attach the test equipment to the vehicle without permanent alteration of 

the fuel storage or evaporative emissions control systems.

(5) The point of attachment to the fuel storage system must allow pressurization to test system 

integrity of the fuel tank and fuel and vapor lines reaching up to and including the gas cap and 

the evaporative canister. An example of an effective attachment point is the evaporative 

emission system test port available on some vehicles.

(c) Leak test procedure. Test a vehicle’s fuel storage system for leaks as follows:

(1) Fill the vehicle’s fuel tank to 40 % capacity.

(2) Soak the vehicle for 6 to 24 hours at a temperature of (20 to 30) °C and maintain this 

temperature throughout the leak test.

(3) Before performing the test, purge the fuel storage system of any residual pressure, bringing 

the system into equilibration with the ambient.

(4) Seal the evaporative canister’s vent to atmosphere and ensure that the system purge valve is 

closed.

(5) Attach the leak test equipment to the vehicle.

(6) Pressurize the fuel storage system with N2 or another inert gas to at least 2.4 kPa. Use good 

engineering judgment to avoid overpressurizing the system.

(7) Maintain gas flow through the system for at least 180 seconds, ensuring that the flow reading 

is stable for an effective leak diameter of ± 0.002 inches.

(8) Use the following equation, or a different equation you develop based on good engineering 

judgment, to calculate the effective leak diameter, Deff.

  

 

0.5057

gas

eff

12 12

0.2153

960

459.67

V

D

pp pp

G T

   

       

Where:

Deff = Effective leak diameter, rounded to the nearest 0.01 inch. 

Vgas = Volumetric flow of gas (scfh).

p1 = Inlet pressure to orifice (psia).

p2 = Atmospheric pressure (psia).

Deleted: d

Deleted: 3

Deleted: nitrogen

Deleted: three minutes

Deleted: P

Deleted: P
G = Specific gravity of gas at 14.7 psia and 60°F.

T = Temperature of flowing medium (°F).

(9) You may perform any number of replicate tests. The average value of replicate tests is the 

official result for a given vehicle.

(10) You may use special or alternative test procedures as described in 40 CFR 1065.10(c).

(d) Equipment calibration. Use good engineering judgment to calibrate the leak check device.

Deleted: ; however, you must perform the same 

number of tests for every vehicle from a given model 

year
Subpart J—[Reserved]
Subpart K—Definitions and Other Reference Material 

§1066.1001 Definitions. 

The definitions in this section apply to this part. The definitions apply to all subparts unless we 

note otherwise. Other terms have the meaning given in 40 CFR part 1065. The definitions 

follow:

 Base inertia means a value expressed in mass units to represent the rotational inertia of 

the rotating dynamometer components between the vehicle driving tires and the dynamometer 

torque-measuring device, as specified in §1066.250.

 C1-equivalent means a convention of expressing HC concentrations based on the total 

number of carbon atoms present, such that the C1-equivalent of an HC concentration equals the 

concentration multiplied by the mean number of carbon atoms in each HC molecule. For 

example, the C1-equivalent of 10 ppm of propane (C3H8) is 30 ppm. C1-equivalent concentration

values may be denoted as “ppmC” in the standard-setting part. Densities may also be expressed 

on a C1 basis. Note that calculating HC masses from concentrations and densities is only valid 

where they are each expressed on the same carbon basis.

Driving schedule means a series of vehicle speeds that a vehicle must follow during a test. 

Driving schedules are specified in the standard-setting part. A driving schedule may consist of 

multiple test intervals. 

Duty cycle means a set of weighting factors and the corresponding test cycles, where the 

weighting factors are used to combine the results of multiple test intervals into a composite result.

 FTP means one of the following:

(1) The test cycle consisting of one UDDS as specified in paragraph (a) of Appendix I of 40 CFR 

part 86, followed by a 10-minute soak with the engine off and repeat driving through the first 

505 seconds of the UDDS. See §1066.801(c)(1).

(2) The entire test procedure for measuring exhaust and/or evaporative emissions as described in 

§1066.801(c).

Footprint has the meaning given in the standard-setting part.

 HFET means the test cycle specified in Appendix I of 40 CFR part 600.

 LA-92 means the test cycle specified in Appendix I, paragraph (c), of 40 CFR part 86.

Nonmethane organic gas (NMOG) means the combination of organic gases other than 

methane as calculated in §1066.665. Note that for this part, the organic gases are summed on a 

mass basis without any adjustment for photochemical reactivity.

Parts-per-million (ppm) means ppm on a molar basis. For hydrocarbon concentrations 

including HC, THC, NMHC, and NMOG, ppm means ppm on a C1-equivalent molar basis.

Road-load coefficients means sets of A, B, and C road-load force coefficients that are 

used in the dynamometer road-load simulation, where road-load force at speed v equals A + B·v

+ C·v

2

.

 SC03 means the test cycle specified in Appendix I, paragraph (h), of 40 CFR part 86.

 SFTP means the collection of test cycles as given in 1066.801(c)(2).

 Standard reference conditions means the following:

(1) Pressure at 101.325 kPa.

(2) Temperature at 293.15 K.

 Test interval means a period over which a vehicle’s emission rates are determined 

separately. For many standards, compliance with the standard is based on a weighted average of 

the mass emissions from multiple test intervals. For example, the standard-setting part may 

Deleted: H

Deleted: 70

Deleted: ¶

1 Hz means are data reported from the instrument 

at a higher frequency, but recorded as a series of 

mean values at a rate of 1 Hz.

Deleted: phase

Deleted: phase

Comment [CAL9]: Adjective? 

Deleted: S

Deleted: S

Deleted: S2

Deleted: 5

Deleted: phase

Deleted: duration 

Deleted: phase

Deleted: for comparison to an emission standard
specify a complete duty cycle as a cold-start test interval and a hot-start test interval. In cases 

where multiple test intervals occur over a duty cycle, the standard-setting part may specify 

additional calculations that weight and combine results to arrive at composite values for 

comparison against the applicable standards. 

 Test weight has the meaning given in §1066.810.

 UDDS means the test cycle specified in Appendix I, paragraph (a), of 40 CFR part 86.

 US06 means the test cycle specified in Appendix I, paragraph (g), of 40 CFR part 86.

 Unloaded coastdown means a dynamometer coastdown run with the vehicle wheels 

removed from the roll surface.

 We (us, our) means the Administrator of the Environmental Protection Agency and any 

authorized representatives.

§1066.1005 Symbols, abbreviations, acronyms, and units of measure. 

The procedures in this part generally follow either the International System of Units (SI) or the 

United States customary units, as detailed in NIST Special Publication 811, which we 

incorporate by reference in §1066.1010. See 40 CFR 1065.20 for specific provisions related to 

these conventions. This section summarizes the way we use symbols, units of measure, and 

other abbreviations. 

(a) Symbols for quantities. This part uses the following symbols and units of measure for 

various quantities: 

Symbol Quantity Unit Unit symbol Unit in terms of SI 

base units 

α atomic hydrogen to carbon ratio mole per mole mol/mol 1

a acceleration feet per second squared or 

meters per second squared ft/s2

 or m/s2 m·s-2

β atomic oxygen to carbon ratio mole per mole mol/mol 1

c conversion factor 

Cd discharge coefficient 

d diameter meters m m 

DF dilution factor 1

e mass weighted emission result grams/mile g/mi

F force pound force or newton lbf or N kg·s-2

f frequency hertz Hz s-1

I inertia pound mass or kilogram lbm or kg kg 

I current ampere A A

i indexing variable 

m mass pound mass or kilogram lbm or kg kg 

N total number in series 

n total number of pulses in a series 

ρ mass density kilogram per cubic meter kg/m3 kg·m-3

R dynamometer roll revolutions revolutions per minute rpm 2·π·60-1· m·m-1·s-1

Re# Reynolds number

Q flow cubic feet or cubic meter 

Q flow rate cfm or cubic meter per 

second 

p pressure pascal Pa m -1·kg·s-2

T Celsius temperature degree Celsius °C K – 273.15 

Deleted: phase

Deleted: phase

Deleted: phase

Deleted: the standard-setting part

Deleted: off the

Deleted: 70

Deleted: 710

Deleted: M

Deleted: RL ... [38]

Deleted: S ... [39]

Deleted: -
T torque (moment of force) newton meter N·m m2

·kg·s-2

t time second s s 

Δt time interval, period, 1/frequency second s s 

U voltage volt V m2·kg·s-3·A-1

v speed miles per hour or meters per 

second mph or m/s m·s-1

VP volume percent

x mass of emission over a test 

interval kilogram kg kg

y generic variable 

(b) Symbols for chemical species. This part uses the following symbols for chemical species and 

exhaust constituents: 

Symbol Species 

CH4 methane 

CO carbon monoxide 

CO2 carbon dioxide 

NMHC nonmethane hydrocarbon 

NMHCE nonmethane hydrocarbon equivalent 

NMOG nonmethane organic gas

NO nitric oxide 

NO2 nitrogen dioxide 

NOx oxides of nitrogen 

N2O nitrous oxide 

O2 molecular oxygen 

OHC oxygenated hydrocarbon

PM particulate matter

THC total hydrocarbon 

THCE total hydrocarbon equivalent 

(c) Superscripts. This part uses the following superscripts to define a quantity: 

Superscript Quantity 

overbar (such as y ) arithmetic mean

(d) Subscripts. This part uses the following subscripts to define a quantity: 

Subscript Quantity 

abs absolute quantity 

act actual or measured condition 

actint actual or measured condition over the speed interval 

atmos atmospheric 

b base 

c coastdown 

comp composite

cor corrected

dexh dilute exhaust quantity

dil dilute

e effective 

Deleted: phase

Deleted: NONMHC ... [40]

Deleted: mass

Deleted: int ... [41]
emission emission specie

error error 

exh raw exhaust quantity

exp expected quantity 

fil filter

final final

flow flow measurement device type

i an individual of a series 

int intake

init initial quantity, typically before an emission test 

max the maximum (i.e. peak) value expected at the standard over a test 

interval; not the maximum of an instrument range

meas measured quantity 

ref reference quantity 

rev revolution 

roll dynamometer roll 

s settling 

sat saturated condition 

span span quantity 

std standard conditions

test test quantity 

uncor uncorrected quantity 

w weighted

zero zero quantity 

 (e) Other acronyms and abbreviations. This part uses the following additional abbreviations and 

acronyms: 

A/C air conditioning

ALVW adjusted loaded vehicle weight

CFR Code of Federal Regulations 

CFV critical-flow venturi

CVS constant-volume sampler

EPA Environmental Protection Agency 

ETW equivalent test weight

EV electric vehicle

FID flame-ionization detector 

FTP Federal test procedure

GC gas chromatograph

GHG greenhouse gas (including CO2, N2O, and CH4)

GVWR gross vehicle weight rating 

HEV hybrid electric vehicle

HFET highway fuel economy test

HLDT heavy light-duty truck

HPLC high pressure liquid chromatography

IBR incorporated by reference

MDPV medium-duty passenger vehicle

NIST National Institute for Standards and Technology 

Deleted: final ... [42]

Deleted: maximum (i.e., peak) value expected at 

the standard over a test interval; not the maximum of 

an instrument range

Deleted: phase

Deleted: si ... [43]
PDP positive-displacement pump

PHEV plug-in hybrid electric vehicle

PM particulate matter

RESS rechargeable energy storage system 

SAE Society of Automotive Engineers 

SC03 air conditioning driving schedule

SEA selective enforcement audit

SFTP supplemental federal test procedure

SSV subsonic venturi

UDDS urban dynamometer driving cycle

US06 aggressive driving schedule

U.S.C. United States Code 

(f) This part uses the following densities of chemical species:

Symbol Quantity1,2 g/m3 g/ft3

ρCH4 density of methane 666.905 18.8847

ρCH3OH density of methanol 1332.02 37.7185

ρC2H5OH C1-equivalent density of ethanol 957.559 27.1151

ρC2H4O C1-equivalent density of acetaldehyde 915.658 25.9285

ρC3H8 density of propane 611.035 17.3026

ρC3H7OH C1-equivalent density of propanol 832.74 23.5806

ρCO density of carbon monoxide 1164.41 32.9725

ρCO2 density of carbon dioxide 1829.53 51.8064

ρHC-gas effective density of hydrocarbon - gaseous fuel3 (see 3) (see 3)

ρHCHO density of formaldehyde 1248.21 35.3455

ρHC-liq effective density of hydrocarbon - liquid fuel4 576.816 16.3336

ρNMHC-gas effective density of nonmethane hydrocarbon - gaseous fuel3 (see 3) (see 3)

ρNMHC-liq effective density of nonmethane hydrocarbon - liquid fuel4 576.816 16.3336

ρNMHCE-gas effective density of nonmethane equivalent hydrocarbon -

gaseous fuel3 (see 3) (see 3)

ρNMHCE-liq effective density of nonmethane equivalent hydrocarbon -

liquid fuel4 576.816 16.3336

ρNOx effective density of oxides of nitrogen5 1912.5 54.156

ρN2O density of nitrous oxide 1829.66 51.8103 1

Densities are given at 20 °C and 101.325 kPa. 2

Densities for all hydrocarbon containing quantities are given in kg/m3-carbon atom and g/ft3-

carbon atom.

3

The effective density for natural gas fuel and liquefied petroleum gas fuel are defined by an 

atomic hydrogen-to-carbon ratio, , of the hydrocarbon components of the test fuel. ρHCgas = 

0.04157·(12.011 + (·1.008)). 4

The effective density for gasoline and diesel fuel are defined by an atomic hydrogen-to-carbon 

ratio, , of 1.85. 5

The effective density of NOx is defined by the molar mass of nitrogen dioxide, NO2.

(g) Constants. (1) This part uses the following constants for the composition of dry air:

Symbol Quantity mol/mol 

xArair amount of argon in dry air 0.00934

xCO2air amount of carbon dioxide in dry air 0.000375

Deleted: S

Deleted: k

Deleted: 0.

Deleted: .

Deleted: 0.

Deleted: 0.

Deleted: 0.

Deleted: 0.

Deleted: .

Deleted: .

Deleted: .

Deleted: 0.

Deleted: 0.

Deleted: 0.

Deleted: .

Deleted: .

Deleted: 

Deleted: 

Deleted: neat 

Deleted: (E0) 
xN2air amount of nitrogen in dry air 0.78084

xO2air amount of oxygen in dry air 0.209445

(2) This part uses the following molar masses or effective molar masses of chemical species:

Symbol Quantity g/mol

(10-3·kg·mol-1)

Mair molar mass of dry air1 28.96559

MH2O molar mass of water 18.01528 1

See paragraph (g)(1) of this section for the composition of dry air.

§1066.1010 Reference materials. 

(a) Certain material is incorporated by reference into this part with the approval of the Director 

of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other 

than that specified in this section, the Environmental Protection Agency must publish a notice of 

the change in the Federal Register and the material must be available to the public. All approved 

material is available for inspection at U.S. EPA, Air and Radiation Docket and Information 

Center, 1301 Constitution Ave., NW., Room B102, EPA West Building, Washington, DC 20460, 

(202) 202-1744, and is available from the sources listed below. It is also available for inspection 

at the National Archives and Records Administration (NARA). For information on the 

availability of this material at NARA, call 202–741–6030, or go to 

http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. 

(b) Society of Automotive Engineers, 400 Commonwealth Dr., Warrendale, PA 15096–0001, 

(877) 606–7323 (U.S. and Canada) or (724) 776–4970 (outside the U.S. and Canada), 

http://www.sae.org. 

(1) SAE J1263, Road Load Measurement and Dynamometer Simulation Using Coastdown 

Techniques, Revised March 2010, IBR approved for §§1066.301(b) and 1066.310(b).

(2) SAE J1634, Electric Vehicle Energy Consumption and Range Test Procedure, Revised 

October 2012, IBR approved for §1066.501.

(3) SAE J1711, Recommended Practice for Measuring the Exhaust Emissions and Fuel Economy 

of Hybrid-Electric Vehicles, Including Plug-In Hybrid Vehicles, Revised June 2010, IBR 

approved for §§1066.122 and 1066.501.

(4) SAE J2263, Road Load Measurement Using Onboard Anemometry and Coastdown 

Techniques, Revised December 2008, IBR approved for §§1066.301(b) and 1066.310(b).

(5) SAE J2264, Chassis Dynamometer Simulation of Road Load Using Coastdown Techniques, 

Issued April 1995, IBR approved for §1066.320.

(6) SAE J2711, Recommended Practice for Measuring Fuel Economy and Emissions of HybridElectric and Conventional Heavy-Duty Vehicles, Issued September 2002, IBR approved for 

§1066.501.

(7) SAE J2951, Drive Quality Evaluation for Chassis Dynamometer Testing, Revised November 

2011, IBR approved for §1066.430.

(c) National Institute of Standards and Technology, 100 Bureau Drive, Stop 1070, Gaithersburg, 

MD 20899-1070, (301) 975-6478, www.nist.gov, or inquiries@nist.gov.

(1) NIST Special Publication 811, 2008 Edition, Guide for the Use of the International System of 

Units (SI), March 2008, IBR approved for §§1066.20(a) and 1066.1005.

(2) [Reserved] 

Deleted: f

Deleted: 710

Deleted: § 

Deleted: 0

Deleted: § 

Deleted: 2

Deleted: § 

Deleted: (4) SAE J2064, R134a Refrigerant 

Automotive Air-Conditioned Hose, Revised 

December 2011, IBR approved for § 1066.840(g).¶

Deleted: 2

Deleted: 5

Deleted: § 

Deleted: ,

Deleted: 3

Deleted: 6

Deleted: 5

Deleted: § 

Deleted: 7

Deleted: 6

Deleted: § 

Deleted: § 

Deleted: 

Deleted: 70
Page 52: [1] Deleted LD Tier III 8/5/2011 12:52:00 PM 

(f) Verify the amount of nonmethane hydrocarbon (or equivalent) contamination in the exhaust 

and background HC sampling systems within 8 hours before the start of the first test drive cycle 

for each individual vehicle tested as described in 40 CFR 1065.520(g). 

§1066.425 Engine starting and restarting. 

(a) Start the vehicle’s engine as follows: 

(1) At the beginning of the test cycle, start the engine according to the procedure you describe in 

your owners manual. In the case of hybrid vehicles, this would generally involve activating 

vehicle systems such that the engine will start when the vehicle’s control algorithms determine 

that the engine should provide power instead of or in addition to power from the rechargeable 

energy storage system (RESS). Unless we specify otherwise, engine starting throughout this part 

generally refers to this step of activating the system on hybrid vehicles, whether or not that 

causes the engine to start running. 

(2) Place the transmission in gear as described by the test cycle in the standard-setting part. 

During idle operation, you may apply the brakes if necessary to keep the drive wheels from 

turning. 

(b) If the vehicle does not start after your recommended maximum cranking time, wait and 

restart cranking according to your recommended practice. If you don’t recommend such a 

cranking procedure, stop cranking after 10 seconds, wait for 10 seconds, then start cranking gain 

for up to 10 seconds. You may repeat this for up to three start attempts. If the vehicle does not 

start after three attempts, you must determine and record the reason for failure to start. Shut off 

sampling systems and either turn the CVS off, or disconnect the exhaust tube from the tailpipe 

during the diagnostic period. Reschedule the vehicle for testing from a cold start. 

(c) Repeat the recommended starting procedure if the engine has a “false start”. 

(d) Take the following steps if the engine stalls: 

(1) If the engine stalls during an idle period, restart the engine immediately and continue the test. 

If you cannot restart the engine soon enough to allow the vehicle to follow the next acceleration, 

stop the driving schedule indicator and reactivate it when the vehicle restarts. 

(2) If the engine stalls during operation other than idle, stop the driving schedule indicator, 

restart the engine, accelerate to the speed required at that point in the driving schedule, reactivate 

the driving schedule indicator, and continue the test. 

(3) Void the test if the vehicle will not restart within one minute. If this happens, remove the 

vehicle from the dynamometer, take corrective action, and reschedule the vehicle for testing. 

Record the reason for the malfunction (if determined) and any corrective action. See the 

standard-setting part for instructions about reporting these malfunctions. 

Page 52: [2] Deleted LD Tier III 8/8/2011 12:23:00 PM 

The overall test consists of prescribed sequences of fueling, parking, and driving at specified test 

conditions. 

(a) Vehicles are tested for criteria pollutants and greenhouse gas emissions as described in the 

standard-setting part. 

(b) Take the following steps before emission sampling begins: 

(1) For batch sampling, connect clean storage media, such as evacuated bags or tare-weighed 

filters. 

(2) Start all measurement instruments according to the instrument manufacturer’s instructions 

and using good engineering judgment. 
(3) Start dilution systems, sample pumps, and the data-collection system. 

(4) Pre-heat or pre-cool heat exchangers in the sampling system to within their operating 

temperature tolerances for a test. 

(5) Allow heated or cooled components such as sample lines, filters, chillers, and pumps to 

stabilize at their operating temperatures. 

(6) Verify that there are no significant vacuum-side leaks according to 40 CFR 1065.345. 

(7) Adjust the sample flow rates to desired levels using bypass flow, if desired. 

(8) Zero or re-zero any electronic integrating devices before the start of any test interval. 

(9) Select gas analyzer ranges. You may automatically or manually switch gas analyzer ranges 

during a test only if switching is performed by changing the span over which the digital 

resolution of the instrument is applied. During a test you may not switch the gains of an 

analyzer’s analog operational amplifier(s). 

(10) Zero and span all continuous gas analyzers using NIST-traceable gases that meet the 

specifications of 40 CFR 1065.750. Span FID analyzers on a carbon number basis of one (C1). 

For example, if you use a C3H8 span gas of concentration 200 mol/mol, span the FID to respond 

with a value of 600 mol/mol. Span FID analyzers consistent with the determination of their 

respective response factors, RF, and penetration fractions, PF, according to 40 CFR 1065.365. 

(11) We recommend that you verify gas analyzer responses after zeroing and spanning by 

sampling a calibration gas that has a concentration near one-half of the span gas concentration. 

Based on the results and good engineering judgment, you may decide whether or not to re-zero, 

re-span, or re-calibrate a gas analyzer before starting a test. 

(12) If you correct for dilution air background concentrations of associated engine exhaust 

constituents, start sampling and recording background concentrations. 

(13) Turn on cooling fans immediately before starting the test. 

(c) Operate vehicles during testing as follows: 

(1) Where we do not give specific instructions, operate the vehicle according to your 

recommendations in the owners manual, unless those recommendations are unrepresentative of 

what may reasonably be expected for in-use operation. 

(2) If vehicles have features that preclude dynamometer testing, modify these features as 

necessary to allow testing, consistent with good engineering judgment. 

(3) Operate vehicles during idle as follows: 

(i) For a vehicle with an automatic transmission, operate at idle with the transmission in “Drive” 

with the wheels braked, except that you may shift to “Neutral” for the first idle period and for 

any idle period longer than one minute. If you put the vehicle in “Neutral” during an idle, you 

must shift the vehicle into “Drive” with the wheels braked at least 5 seconds before the end of 

the idle period. 

(ii) For vehicles with manual transmission, operate at idle with the transmission in gear with the 

clutch disengaged, except that you may shift to “Neutral” with the clutch disengaged for the first 

idle period and for any idle period longer than one minute. If you put the vehicle in “Neutral” 

during idle, you must shift to first gear with the clutch disengaged at least 5 seconds before the 

end of the idle period. 

(4) Operate the vehicle with the appropriate accelerator pedal movement necessary to achieve the 

speed versus time relationship prescribed by the driving schedule. Avoid smoothing speed 

variations and excessive accelerator pedal perturbations. 

(5) Operate the vehicle smoothly, following representative shift speeds and procedures. For 

manual transmissions, the operator shall release the accelerator pedal during each shift and 
accomplish the shift with minimum time. If the vehicle cannot accelerate at the specified rate, 

operate it at maximum available power until the vehicle speed reaches the value prescribed for 

that time in the driving schedule. 

(6) Decelerate without changing gears, using the brakes or accelerator pedal as necessary to 

maintain the desired speed. Keep the clutch engaged on manual transmission vehicles and do not 

change gears after the end of the acceleration event. Depress manual transmission clutches when 

the speed drops below 6.7 m/s (15 mph), when engine roughness is evident, or when engine 

stalling is imminent. 

(7) For test vehicles equipped with manual transmissions, shift gears in a way that represents 

reasonable shift patterns for in-use operation, considering vehicle speed, engine speed, and any 

other relevant variables. You may recommend a shift schedule in your owners manual that 

differs from your shift schedule during testing as long as you include both shift schedules in your 

application for certification. In this case, we may use the shift schedule you describe in your 

owners manual. 

Page 59: [3] Deleted LD Tier III Round 6 1/18/2013 12:58:00 PM 

mass of 

Page 59: [3] Deleted LD Tier III Round 6 1/18/2013 12:58:00 PM 

mass of 

Page 59: [3] Deleted LD Tier III Round 6 1/18/2013 12:58:00 PM 

mass of 

Page 59: [4] Deleted LD Tier III Round 6 12/19/2012 12:05:00 PM 

phase 

Page 59: [4] Deleted LD Tier III Round 6 12/19/2012 12:05:00 PM 

phase 

Page 59: [5] Deleted LD Tier III Round 6 1/18/2013 1:16:00 PM 

measured in 

Page 59: [5] Deleted LD Tier III Round 6 1/18/2013 1:16:00 PM 

measured in 

Page 59: [6] Deleted LD Tier III Round 6 1/23/2013 8:41:00 AM 

925 

Page 59: [6] Deleted LD Tier III Round 6 1/23/2013 8:41:00 AM 

925 

Page 59: [7] Deleted LD Tier III Round 6 1/18/2013 1:27:00 PM 

. 

Page 59: [7] Deleted LD Tier III Round 6 1/18/2013 1:27:00 PM 

. 

Page 59: [8] Deleted LD Tier III Round 6 1/23/2013 1:58:00 PM 

Calculate the mass of particulate matter emission 

Page 59: [8] Deleted LD Tier III Round 6 1/23/2013 1:58:00 PM 

Calculate the mass of particulate matter emission 

Page 59: [9] Deleted LD Tier III Round 6 1/23/2013 1:55:00 PM 
If you sample PM onto a single filter per test phase as described in §1066.822(c) or onto a single 

filter per UDDS test phase as described in §1066.820(b)(3) or 

Page 59: [10] Deleted LD Tier III Round 6 12/19/2012 12:05:00 PM 

phase 

Page 59: [10] Deleted LD Tier III Round 6 12/19/2012 12:05:00 PM 

phase 

Page 59: [11] Deleted LD Tier III Round 6 1/23/2013 3:07:00 PM 

Vgasstd = total volume of sample flow through the gaseous emission bench over the test phase at 

standard temperature and pressure. 

VPMstd = total volume of dilute exhaust sampled 

Page 59: [12] Deleted LD Tier III Round 6 1/23/2013 3:07:00 PM 

through the filter over the test phase at standard temperature and pressure. 

Page 59: [13] Deleted LD Tier III Round 6 1/22/2013 3:55:00 PM 

Vmixstd = total dilute exhaust volume over the test phase at the flow meter at standard reference 

conditions of 293.15 K and 101.3 kPa. 

Page 59: [14] Deleted LD Tier III Round 6 1/22/2013 3:53:00 PM 

5 

Vmixstd = 170.492 m3, where Vmixact = 170.72 m3, pB = 101.7 kPa, pin = 0 kPa, and Tin = 294.7 K 

Using 

Page 59: [15] Deleted LD Tier III Round 6 1/22/2013 3:53:00 PM 

5 

Vgasstd = 0.0291 m3, where Vgasact = 0.0337 m3, pB = 101.7 kPa, pin = 0 kPa, and Tin = 340.5 K 

Using 

Page 59: [16] Deleted LD Tier III Round 6 1/22/2013 3:53:00 PM 

5 

VPMstd = 0.9248 m3

, where VPMact = 1.07 m3, pB = 101.7 kPa, pin = 0 kPa, and Tin = 340.5 K 

Using 

Page 59: [17] Deleted LD Tier III Round 6 1/22/2013 3:53:00 PM 

5 

Vsdastd = 0.527 m3, where Vsdaact = 0.531 m3, pB = 101.7 kPa, pin = 0 kPa, and Tin = 296.3 K 

Vmix = 170.492 + 0.0291 + 0.9248 – 0.527 = 170.919 m3

Page 59: [18] Deleted LD Tier III Round 6 1/23/2013 1:51:00 PM 

for all test phases 

Page 59: [18] Deleted LD Tier III Round 6 1/23/2013 1:51:00 PM 

for all test phases 

Page 66: [19] Deleted LD Tier III Round 6 1/18/2013 4:37:00 PM 

(2) For the SC03 test cycle, use the following equation to correct measured concentrations to a 

reference condition of 10.71 of H2O vapor per kilogram of dry air: 

  NOxdexhcor NOxdexh

0.8825

1 0.0329 10.71

x x

H    

 Eq. 1066.630-3 
Where: 

H = Absolute humidity in grams of H2O vapor per kilogram of dry air according to Eq. 

1066.630-2. 

Example:

RH = 55.9 % 

Pd = 2.93 kPa 

PB = 96.71 kPa 

H = 10.7148 g H2O vapor/kg dry air 

xNOxdexh = 1.2 ppm 

  NOxdexhcor

0.8825 1.2 1.059 ppm 1 0.0329 10.7148 10.71

x    

Page 66: [20] Deleted LD Tier III Round 4 9/10/2012 4:08:00 PM 

 calibration equations on a molar basis; however, 40 CFR 1065.640(a) allows for conversion 

between volumetric and molar flow rate. If you are using mass-based emission calculations to 

determine your total mass of emissions over a test cycle, you may calibrate your flow meters 

volumetrically using Equation 1065.640-1 to convert the molar flow calibration equations 

throughout all of 40 CFR 1065.640 to volumetric flow equations 

Page 66: [21] Deleted LD Tier III Round 6 1/18/2013 4:58:00 PM 

 After you calibrate a flow meter using these calculations, use the calculations described in 

§1066.652 to calculate flow during an emission test. 

Page 66: [22] Deleted LD Tier III Round 6 1/18/2013 4:58:00 PM 

For each restrictor position, calculate the following values from the mean values determined in 

§1066.140, as follows: 

Page 66: [23] Deleted LD Tier III Round 6 1/18/2013 5:04:00 PM 

nPDP f = 1205.1 r/min = 20.085 r/s 

Page 74: [24] Deleted LD Tier III Round 6 1/19/2013 3:08:00 PM 

Unless the standard-setting part specifies otherwise, u 

Page 74: [24] Deleted LD Tier III Round 6 1/19/2013 3:08:00 PM 

Unless the standard-setting part specifies otherwise, u 

Page 74: [24] Deleted LD Tier III Round 6 1/19/2013 3:08:00 PM 

Unless the standard-setting part specifies otherwise, u 

Page 74: [24] Deleted LD Tier III Round 6 1/19/2013 3:08:00 PM 

Unless the standard-setting part specifies otherwise, u 

Page 74: [25] Deleted LD Tier III Round 6 1/19/2013 3:19:00 PM 

mOHCi = the C1-equivalent mass of oxygenated species i in the exhaust calculated using Eq. 

1066.610-1 and the density of the oxygenated species i as given in §1066.1005(f). 

Page 74: [25] Deleted LD Tier III Round 6 1/19/2013 3:19:00 PM 

mOHCi = the C1-equivalent mass of oxygenated species i in the exhaust calculated using Eq. 

1066.610-1 and the density of the oxygenated species i as given in §1066.1005(f). 
Page 74: [25] Deleted LD Tier III Round 6 1/19/2013 3:19:00 PM 

mOHCi = the C1-equivalent mass of oxygenated species i in the exhaust calculated using Eq. 

1066.610-1 and the density of the oxygenated species i as given in §1066.1005(f). 

Page 74: [25] Deleted LD Tier III Round 6 1/19/2013 3:19:00 PM 

mOHCi = the C1-equivalent mass of oxygenated species i in the exhaust calculated using Eq. 

1066.610-1 and the density of the oxygenated species i as given in §1066.1005(f). 

Page 74: [26] Deleted LD Tier III Round 6 1/23/2013 2:09:00 PM 

-liq 

Page 74: [26] Deleted LD Tier III Round 6 1/23/2013 2:09:00 PM 

-liq 

Page 74: [26] Deleted LD Tier III Round 6 1/23/2013 2:09:00 PM 

-liq 

Page 74: [27] Deleted LD Tier III Round 6 12/27/2012 9:51:00 AM 

You may generate your own response factors or use the following response factors, consistent 

with good engineering judgment: 

Table 1 of §1066.665–Default values for THC FID 

response factor relative to propane on a C1-equivalent basis 

Compound Response factor (RF) 

methanol 0.63 

ethanol 0.75 

propanol 0.85 

formaldehyde 0.00 

acetaldehyde 0.50 

Page 74: [28] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [28] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [29] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [29] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [30] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [30] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [31] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 

Page 74: [31] Deleted LD Tier III Round 6 1/19/2013 3:34:00 PM 

000 
Page 74: [32] Deleted LD Tier III Round 6 1/19/2013 3:35:00 PM 

000 

Page 74: [32] Deleted LD Tier III Round 6 1/19/2013 3:35:00 PM 

000 

Page 74: [33] Deleted LD Tier III Round 6 1/19/2013 3:35:00 PM 

0. 

Page 74: [33] Deleted LD Tier III Round 6 1/19/2013 3:35:00 PM 

0. 

Page 74: [34] Deleted LD Tier III Round 6 1/19/2013 3:36:00 PM 

. 

Page 74: [34] Deleted LD Tier III Round 6 1/19/2013 3:36:00 PM 

. 

Page 74: [35] Deleted LD Tier III Round 6 1/19/2013 3:36:00 PM 

0. 

Page 74: [35] Deleted LD Tier III Round 6 1/19/2013 3:36:00 PM 

0. 

Page 74: [36] Deleted LD Tier III Round 6 1/19/2013 3:36:00 PM 

. 

Page 74: [36] Deleted LD Tier III Round 6 1/19/2013 3:36:00 PM 

. 

Page 74: [37] Deleted LD Tier III Round 6 1/19/2013 3:37:00 PM 

0. 

Page 74: [37] Deleted LD Tier III Round 6 1/19/2013 3:37:00 PM 

0. 

Page 98: [38] Deleted LD Tier III Round 6 1/18/2013 12:02:00 PM 

RL road-load coefficient horsepower or kilowatt hp or kW 103·m2·kg·s-3

Page 98: [39] Deleted LD Tier III 8/23/2011 7:59:00 AM 

S speed miles per hour or meters per 

second mph or m/s m·s-1

Page 99: [40] Deleted LD Tier III Round 6 1/19/2013 3:50:00 PM 

NONMHC nonoxygenated nonmethane hydrocarbon 

Page 99: [41] Deleted LD Tier III 4/11/2012 10:51:00 AM 

int speed interval 

Page 100: [42] Deleted LD Tier III 4/11/2012 10:51:00 AM 

final final 

Page 100: [43] Deleted LD Tier III 8/22/2011 3:34:00 PM 

si speed interval