MEMORANDUM

FROM: Aron Butler 

Assessment and Standards Division

US EPA Office of Transportation and Air Quality

TO: Tier 3 Docket EPA-HQ-OAR-2011-0135

DATE: April 29, 2013

SUBJECT: Data Collected in EPAct Fuel Effects Study Pilot Phases 

Background

Section 1506 of the Energy Policy Act of 2005 required EPA to produce an updated fuel effects 

model representing the current (at that time) light-duty gasoline fleet, including determination of 

emission impacts of increased renewable fuel use. The resulting data collection activities came 

to be known as the EPAct test programs. 

Prior to beginning emission measurements for the main statistically-optimized matrix of 27 test 

fuels (also referred to as EPAct Phase 3 or EPAct/V2/E-89), EPA wished to perform a pilot 

study looking at impacts of ethanol blends on a representative fleet of Tier 2 vehicles. This pilot 

work would also serve as a check-out of procedural, analytical, and reporting requirements that 

the contractor (Southwest Research Institute) should meet before moving on to the much larger 

Phase 3 program.

1

Goals and Design

This pilot testing consisted of emission measurements on the LA92 cycle for each of three fuels 

on each of 19 test vehicles. The fuels were a non-ethanol base fuel, a10% ethanol blend, and a 

15% ethanol blend (also referred to by their program designations 17, 18, and 19, respectively). 

The fuel properties were intended to approximate what typical market fuels of those types did or 

would look like, and the vehicles were to be representative of high sales makes and models. 

Table 1 shows test fuel properties and Table 2 the test vehicle models and engine configurations. 

More detailed description of vehicle fleet selection is available in the EPAct/V2/E-89 testing 

report.2

 

1

See report number EPA-420-R-13-002, “Assessing the Effect of Five Gasoline Properties on Exhaust Emissions 

from Light-Duty Vehicles certified to Tier-2 Standards”, available in the Tier 3 Docket EPA-HQ-OAR-2011-0135,

or on the web at http://www.epa.gov/otaq/models/moves/epact.htm.
Table 1. EPAct Phase 1-2 Test Fuel Properties.

Property Unit Method

Test Fuel

17 (E0) 18 (E10) 19 (E15)

Ethanol vol% D5599 <0.10 9.37 14.57

T50 °F D86 215.3 211.8 202.4

T90 °F D86 322.0 319.3 313.6

RVP psi D5191 9.20 9.08 9.05

Aromatics vol% D1319 29.1 23.1 22.0

Olefins vol% D1319 6.6 7.4 6.5

Benzene vol% D3606 0.55 0.55 0.45

Sulfur mg/kg D2699 23 23 20

RON - D2699 93.1 93.7 93.6

MON - D2700 83.5 85.1 84.4

(R+M)/2 - Calc. 88.3 89.4 89.0

Table 2. EPAct Phase 1-2 Test Vehicle Summary.

Procedures 

For Phase 1, the testing was performed at a nominal temperature of 75°F and for Phase 2 at 50°F. 

Fuels were tested in order of ascending ethanol content in each of Phases 1 and 2, with replicates 

on the same fuel being performed back-to-back. A summary of fuel change and prep procedures 

MAKE BRAND MODEL (all 2008 model year) ENGINE

Chrysler Dodge Caliber 2.4L I4

Chrysler Dodge/Chrysler Caravan/Town&Country 3.3L V6

Chrysler Jeep Liberty 3.7L V6

Ford Ford Focus 2.0L I4

Ford Ford 500/Taurus/Freestyle 3.0L V6

Ford Ford F150 5.4L V6

Ford Ford/Mercury Explorer/Mountaineer 4.0L V6

GM Buick/GMC/Saturn Enclave/Acadia/Outlook 3.6L V6

GM Chevrolet Cobalt/HHR 2.4L I4

GM Chevrolet Impala 3.5L V6

GM Chevrolet/GMC Avalanche/Silverado 5.3L V8

Honda Honda Civic 1.8L I4

Honda Honda Accord 2.4L I4

Honda Honda Odyssey 3.5L V6

Nissan Nissan Altima 2.5L I4

Toyota Toyota Corolla 1.8L I4

Toyota Toyota Camry 2.4L I4

Toyota Toyota Sienna 3.3L V6

Toyota Toyota Tundra 4.0L V6
is shown in Table 3. All fuel-vehicle combinations were tested twice, with a third replicate being 

performed in cases where the variability criteria shown in Table 4 were exceeded.

Table 3. Summary of Fuel Change, Prep, and Test Procedures.

Step Description

1 Drain vehicle fuel completely via fuel rail whenever possible

2

Turn vehicle ignition to RUN position for 30 seconds to allow controls to allow fuel level reading to 

stabilize. Confirm the return of fuel gauge reading to zero

3

Fill fuel tank to 40% with next test fuel in sequence. Fill-up fuel must be at the temperature of the next 

LA92 test (75 or 50oF)

4

Start vehicle and execute catalyst sulfur removal procedure described in Appendix C of CRC E-60 Program 

report

5

Drain fuel and refill to 40% with test fuel. Fill-up fuel must be at the temperature of the next LA92 test (75 

or 50oF)

6 Start vehicle and drive one LA4 cycle. Allow vehicle to idle in park for 2 minutes before engine shut-down

7 Move vehicle to soak area without starting or driving

8 Park vehicle in soak area at proper temperature (75 or 50oF) for 12-36 hours

9 Move vehicle to test area without starting engine

10 Perform LA92 cycle emissions test

11 Park vehicle in soak area of proper temperature for 12-36 hours

12 Move vehicle to test area without driving

13 Perform LA92 emissions test

14 Determine whether third replicate is necessary, based on data variability criteria (see Table 4 below)

15 If a third replicate is required, repeat steps 10, 11 and 12

16 If third replicate is not required, return to step 1 and proceed with next fuel in test sequence

Table 4. Variability Criteria for Triplicate Testing.

Dilute Gaseous 

Emission

Criteria for requiring a third test 

(composite cycle emissions)

CO2 Ratio of higher / lower > 1.04

NOx Ratio of higher / lower > 1.81

NMHC Ratio of higher / lower > 1.67
Pollutants reported at the bag level included THC, CH4, CO, CO2, NOx, NMHC, and particulate 

mass. Modal (second by second) tailpipe measurements were also collected for several gaseous 

pollutants. Results comparing NMHC and NOx emissions between the 0% and 10% ethanol 

fuels are available in an earlier memo to the RFS2 docket.2

Exhaust speciation of alcohols, carbonyls, and C2-C12 hydrocarbons was performed for bag 1 of 

all tests, plus bags 2-3 for all tests on the following subset of three vehicles: Silverado, Civic, 

Sienna. 

Following the completion of Phase 2, emissions data were collected over the FTP cycle for a 

subset of six vehicles (Accord, Altima, Camry, Caravan, Focus, Silverado) on the three pilot 

fuels. Fuels were tested in descending order of ethanol content. Alcohol, carbonyl, and 

hydrocarbon speciation was performed in bag 1. This data was intended to enable comparison of 

the Phase 1-2 results with historical datasets collected over the FTP.

During review of exhaust speciation results being collected during Phase 1, high proportions of 

some blendstock components (e.g., cyclohexane) were noticed for the E0 and E10. This was 

suggestive that the fuel blender may have used higher proportions of specific compounds relative 

to typical commercial gasoline, and this was verified with subsequent fuel analyses. While this 

was not optimal, and suggested fuel blending would need to be more highly specified in later 

program phases, pilot testing was completed using the available fuels.

The intent had originally been to fold the data from pilot fuels (17, 18, 19) into the Phase 3 

dataset when producing the final emission models. However, we later decided against it for a 

number of reasons related to improvements made in vehicle handling and prep procedures (e.g., 

fuel carryover and fuel trim learning) between Phases 1 and 3, as well as the concerns related to 

fuel blending highlighted above.

Data collection activities for these pilot phases occurred between April 2008 and January 2009.

Availability of Data

A summary database file containing fuel, vehicle, and emission data for Phases 1, 2 and FTP 

testing is available in the docket as an Excel file with name “EPAct Pilot data summary April 

2013.xlsx”. 

As described in a separate report, speciation profiles based on data from this program were 

developed and included in EPA’s SPECIATE database for emission source profiles.

3

 

2

See document number EPA-HQ-OAR-2005-0161-3157 in docket EPA-HQ-OAR-2005-0161.

3

See report number EPA-420-R-09-002, “Exhaust Emission Profiles for EPA SPECIATE Database: Energy Policy 

Act (EPAct) Low-Level Ethanol Fuel Blends and Tier 2 Light-Duty Vehicles”, available in the Tier 3 Docket EPAHQ-OAR-2011-0135.