EPA-AA-TEB-84-1
A Study of Emissions From Twenty High Mileage
1980 Model Year Passenger Cars
Equipped with the GM 350 CID Diesel Engine
by
Thomas C. Bejma
November 1983
Test and Evaluation Branch
Emission Control Technology Division
Office of Mobile Sources
U.S. Environmental Protection Agency
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ABSTRACT
This report describes the results of an exhaust emission testing program
conducted by EPA on twenty diesel-powered General Motors passenger cars.
Each was a full size 1980 model equipped with a 350 CID engine (family
designation: 03J9ZG). The primary purpose of this program was to assess
the emission durability of this engine which in 1980 was equipped with an
EGR system and technological improvements to reduce hydrocarbon, NOX,
and particulate emissions. A secondary objective was the gathering of
samples for subsequent Ames Test analyses.
Test vehicles were recruited from the general public within 20 miles of
the MVEL using direct mail solicitation. Names were drawn at random from
the State motor vehicle registration lists. Only vehicles with over
40,000 miles were sought. This resulted in an average odometer reading
for the test fleet of 70,000 miles. The program began in July, 1983 and
was completed in September, 1983. Testing was performed at the EPA's
Motor Vehicle Emission Laboratory in Ann Arbor.
Only 20% of the vehicles met their standards; however, the average
emission levels for CO and NOX were very close to those resulting from
the Certification process at 4,000 miles. Particulate and hydrocarbon
levels, on the other hand, did show some deterioration, by a factor of
about two.
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INTRODUCTION
Although the diesel engine has been recognized as a durable and
fuel-efficient powerplant, its use in passenger cars has been limited due
to weight and initial cost. However, its inherently high fuel efficiency
has brought it into much wider use with a resultant need to regulate
particulate emissions. In an effort to meet the regulatory requirements
and improve the durability of the engine, several technological changes
have occurred with the GM 350 CID diesel. For the 1980 model year,
General Motors added an EGR system to reduce the NOX emissions, and
also changed the type of injectors*, to reduce the HC and particulate
levels.
PURPOSE
On the basis of the facts above, an EPA test program was designed to
measure the emission durability of both the EGR and new injection systems
to project future emission levels of these engines.
PROGRAM DESIGN
The program employed the normal Emission Factor procedures in terms of
the solicitation of test vehicles. Each vehicle selected was to undergo
a single FTP test by the EPA laboratory. An underhood inspection of
emission-related components was to follow each test. Vehicles equipped
with the 350 CID engine were combined to form a single "universe." The
sample area consisted of those zip codes within a 20 mile radius of the
Motor Vehicle Emission Laboratory. These lists were compiled by EPA's
Enforcement Division from registration data obtained from the State of
Michigan Department of Motor Vehicles. The resultant sample size was
1634 vehicles. The list of owners was then randomized and printed on
mailing labels for ease of procurement. To obtain the required number of
vehicles, 300 letters were mailed in two blocks of 150 each. The actual
procurement function was accomplished by EG&G Automotive Research under
contract to EPA. All of the testing was performed by EPA in the E&D
laboratory. A list of the vehicles tested is shown in Appendix A.
Prior to 1980, pencil type injectors were used by GM. In mid-1979 GM
began experimenting with a "poppet" type injector to avoid a constant
drip associated with the pencil type injectors. With the start of
the 1980 model year, GM used the poppet type of injector
exclusively. This new fuel delivery system was designed to reduce
levels of particulates below the 1982 standard of .6 gm/mi.
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PARTICIPANT PROFILE
Each owner was asked a number of questions regarding his/her use and
maintenance of the vehicle. Almost all of the vehicle owners said they
were involved in sales or commuted long distances to work. Most were
concerned with fuel economy. Most owners were satisfied with the
performance of their vehicle's engine although some had experienced major
problems with injector pumps, injectors, or other minor annoyances such
as oil leaks. Most felt they had maintained their vehicles in accordance
with the manufacturer's recommendations.
VEHICLE TESTING
Once each vehicle was delivered for testing by the procurement
contractor, an E&D technician preconditioned the vehicle for testing the
following day. Other than topping off low fluid levels (oil, water,
brake fluid) no other maintenance was performed on the vehicles prior to
testing. Several vehicles had to have their exhaust systems repaired or
replaced due to significant leaks prior to testing. The leaks were due
to fatigue and rust and were found along the various flanges and hangers
of the exhaust system. The leaks were not of sufficient size to be a
noise or health problem to the driver but were of a size to inhibit the
collection of a valid sample during a test. Following replacement, 50
miles of preconditioning were accumulated on the vehicle.
Each vehicle was drained of its "as received" fuel and filled to standard
volume (40%) with EPA's Diesel #2 fuel from laboratory stock. Each
vehicle was tested only once.
EMISSION TEST RESULTS
Complete FTP results for each vehicle are shown in Appendix A. Despite
their high mileage (70,000 miles), the average CO and NOX emission
levels of these vehicles are not very different from the levels of
Emission Data vehicles tested at 4,000 miles. The average HC emissions
of 0.57 gm/mi, however, exceed the standard of 0.41 gm/mi by 0.16 grams
per mile. This 0<.57 gm/mi level is approximately twice the Certification
level of 0.32 gm/mi for these engines. Listed in Table 1 are the average
emissions of: 1) the original certification tests of this family, 2) the
vehicles tested in this program, 3) vehicles in this program with less
than 50,000 miles, 4) vehicles in this program with over 50,000 miles,
and 5) the results from a previous EPA program on 1978 GM high mileage
diesels. Figure 1 displays the pass/fail outcome of the fleet in this
program.
PASS - 202
FAIL liox O;;LY - 5%
FAIL HC ONLY - 75;
FIGURE 1
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Table 1
Federal Test Procedure (gin/mi)
Emission Levels of 1980 MY 350 CID GM Diesels
City %
N_ Odom H£ C0_ NOx Particulate MPG Passing
Certification 4 4,000 .32 1.3 1.65 * 22.0 100
1980 Stds. .41 7.0 2.0
This program 20 70,006 .57 1.4 1.64 .70 20.9 20
This program
under 50K 7 45,169 .42 1.1 1.56 .47 21.7 15
Over 50K 13 83,379 .62 1.5 1.72 .74 20.5 5
For Comparison
1978 MY** 18 48,782 .80 1.6 1.35 .85 21.5 94
*Not available
**Results from EPA-AA-TEB-80-11 (March 1980) for comparison.
As these results show, levels of particulate emissions from these high
mileage vehicles are below the 1982 standard of .6 gm/mi for their
"useful life" (i.e., 50,000 miles). NOX emission levels are below the
2.0 gram standard even though 15 of the 20 vehicles exhibited some form
of EGR problem. Figure 2 displays the results of this program versus
mileage.
The problems with the EGR system on many of these vehicles were primarily
due to carbon build-up, preventing the valve from sealing properly.
Thus, the failure resulted in EGR flow during all phases of operation
rather than a complete failure to operate. This may be due to their
advanced mileage and the inherently dirty diesel exhaust. Vehicle 15 and
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vehicle 18 have particulate versus mileage results which are opposite,
one lower, one higher, than all the others. A review of the inspection
forms revealed that vehicle 15 had a leaky injection pump while vehicle
18 had its pump recently replaced with a new one. This could explain the
differences.
A secondary objective of this program was the collection of samples for
AMES testing. These samples have been collected and are in storage
awaiting the backlog of analyses.
CONCLUSIONS
Hydrocarbon and particulate levels at high mileage exhibit greater
increases than CO and NOX. The absolute levels of HC and particulates
increased by about a factor of two from 4,000 mile data. The changes GM
made to its fuel delivery system were successful in achieving particulate
levels below the 1982 standard. The durability of the EGR system on
diesel engines is questionable, although the NOX generally remained
below the standard.
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Appendix A
1980 High Mileage GM 350 CID Diesels
Mile
HC
CO
NOx
Part MPG
*1.
2.
*3.
*4.
*5.
6.
*7.
*8.
*9.
*10.
11.
*12.
*13.
*14.
15.
*16.
17.
*18.
*19.
*20.
Bonneville
Toronado
Toronado
Caprice S/W
Cue lass
Delta 88
Cutlass LS
Cutlass
98
Cutlass LS
Custom Cruiser S/W
Bonneville
Park Avenue
Seville
Caprice S/W
Delta 88
98
Delta 88
Delta 88
Cutlass LS
46910
46086
51519
83516
48496
71074
47177
118645
67254 '
91553
118970
51170
43424
43439
40654
90761
78802
109441
76652
74572
.62
.21
1.16
.92
.47
.31
.38
.66
.44
1.00
.55
.62
.28
.42
.96
.24
.53
.54
.62
.48
1.
0.
1.
1.
1.
1.
0.
2.
1.
1.
1.
1.
0.
1.
2.
1.
1.
1.
1.
1.
21
84
80
70
22
07
86
23
04
89
56
32
95
22
29
95
24
29
03
21
1.
1.
1.
1.
1.
1.
2.
1.
1.
1.
1.
1.
1.
1.
1.
3.
1.
1.
1.
1.
37
89
41
55
08
41
03
14
66
65
92
50
58
34
16
13
87
66
96
54
.52
.42
.66
.69
.48
.51
.38
1.13
.52
.89
1.22
.56
.48
.57
1.33
1.17
.75
.45
.71
.38
22.
23.
20.
18.
22.
21.
24.
21.
21.
21.
19.
21.
21.
20.
17.
17.
20.
21.
21.
22,
8
8
2
4
9
5
1
5
9
1
3
6
4
8
7
,3
5
1
2
,2
Average
70006
0.57
1.40
1.64
.70
20.9
*Vehicles with EGR problems,
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