74-21 DWP
A Study of Fuel Economy Changes
Resulting from Tampering
with Emission Controls
January 1974
Test and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
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Fuel Economy Chcn^es.Resulting from Tampering
with Emission Controls
INTRODUCTION
As a result of recent concern over vehicle fuel economy, EPA has
received numerous inquiries relating to the influence of emission controls
on vehicle fuel consumption. Statements have appeared in the press and
elsewhere indicating that motorists r.ight ir.prove their fuel economy as
much as 25% by merely having a service station adjust the emission control
systems. Because to EPA technical staff such claims appeared to be
exaggerations, a test program was undertaken to quantify the fuel economy
and emission change which would result from disconnecting emission controls
and to determine whether private service garages could effectively improve
fuel economy.
A group of ten late model (1973 and 1974) cars were obtained
representing the full range of typical vehicle weights encountered in
the existing vehicle population. The 1973 and 1974 automobiles selected
for this program incorporate more alterations for low emissions than
earlier models. (See Appendix A for a technical discussion of such
alterations.) These vehicles have shown the greatest change in fuel
economy from uncontrolled cars. On a sales weighted average 1973/74
cars are 10 to 11% lower in economy than the uncontrolled cars of
equivalent weight. Successful re-optimization of these vehicles for
best fuel economy would result in greater improvements than should be
possible for 1972 and earlier models.
A number of garages were contacted with the request that "they
do whatever they could" to improve gasoline mileage. In most of the
cases the garages were not informed that the work was part of a test
program for EPA so that results of any work done would be comparable to
that performed for any private individual.
The majority of garages contacted declined to do the work either
for the reason that they thought, such work was illegal or because they
did not want to contribute to deterioration of air quality, but 25% of the
garages agreed to do the work. Some of these garages claimed that they
could improve both performance and fuel economy with little impact on
emissions; others were uncertain and asked for customer assessment of
the results.
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The basic test approach utilized in the program consisted of the
following sequence of events:
(1) EPA inspection of vehicle and engine tune-up to manufacturers'
specifications.
(2) Recording of carburetor and distributor specifications.
(3) Replicate EPA dynamometer test of vehicle to measure emissions
and fuel economy utilizing the Federal Test Procedure.
(4) Tampering of the emission control system by either EPA
mechanics or private garages.
(5) EPA dynamometer test of vehicle to measure emissions and
fuel economy as in (3) above.
(6) EPA mechanics restore vehicle to manufacturers'
specifications.
(7) EPA dynamometer test for emissions and fuel economy as in
steps (3) and (5).
(8) Repeat test sequence above to Insure that each vehicle was
tested at least once to EPA and garage tamper.
Seven out of the ten vehicles were subjected to this basic approach.
(Some vehicles were used more than once, for a total of 13 garage
tampering episodes.) The dynamometer tests [steps (3), (5), and (7)]
provided the comparative basis for determining the changes in fuel economy
and exhaust emissions resulting from the tampering effort. This permitted
conclusions to be drawn as to what fuel economy gains are achievable and
what gains typical mechanics would make. Data on the emission and economy
changes are shown in the attached tables and discussed in the Test Results
section.
Three of the ten vehicles also followed the basic test approach
above except the vehicles were not tuned by EPA prior to EPA dynamometer
test and delivery to garages for tampering. The purpose of this deviation
from the basic test approach was twofold: to ascertain whether the EPA
tune-up was inadvertently assisting or biasing the garage tampering
attempts and to obtain data on a real-world basis, i.e., tampering with
an "as-received" vehicle would represent the normal challenge to the garage.
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The attached Table 1 lists the ten test vehicles. Also shown is
whether EPA tampered with the vehicle, and the garages that did
tamper with the vehicle. All vehicles were rented from rental agencies
or new car dealers. During the test program the 1972 Federal Test
Procedure (FTP), as described in the November 15, 1972, Federal Register
was used to determine emissions. Fuel economy for the '72 FTP driving
cycle, which represents the typical urban commuter trip, was determined
using the carbon mass balance technique. For a detailed discussion of
this fuel economy test, see A Report or. Automobile Fuel Econory, October
1973, by the United States Environmental Protection Agency, Office of
Air and Water Programs, Office of Mobile Source Air Pollution Control.
The first seven vehicles listed in Table I were tuned to manufacturers'
specifications by EPA before initial baseline testing. Except in the case
of the '74 Pinto, for which replacement parts could not be obtained in
time, the tune-up included installation of new plugs, points, condenser,
rotor, and air cleaner. These vehicles were then modified by EPA and by
at least one of eight garages in the Detroit metropolitan area. Except
for garages B & D, there was no knowledge by the garages that their
work was part of an EPA tampering test program. Emission and fuel economy
testing was conducted by EPA after each modification. The last three
vehicles listed in Table I were tested by EPA as received and then taken
to garages for modifications without initial tune-ups in order to see
what gross effect could b°e associated with a vehicle in a "typical" state
of tune.
In all cases the EPA modification consisted of adjustment of ignition
and fuel system parameters without modification or replacement of parts,
and the disconnection of specific emission control devices that are
external to the basic engine system.
The EPA modifications were made by engineers and technicians who
have detailed knowledge of automotive emission control systems, as
well as access to sophisticated test equipment. This level of skill
and facilities is not ordinarily found in the average repair garage, as
the test results will indicate.
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TEST RESULTS
Table II summarizes the results of this test program. It
can be seen from the EPA codification results that an average improvement
of fuel economy of 7.0% was achieved. On the other hand, modifications
by eight different garages in 13 different cases showed an average decrease
in economy of 3.5%. The increases in emissions associated with the
tampering are included in the tables, and must be compared to applicable
standards of HC = 3.4 grams per nile (gpm), CO = 39 gpm, NOX = 3.1 gpm,
and to average emissions from pre-controlled cars of HC = 9.6 gpm,
CO * 95 gpm, and NOX = 3.5 gpm.
Tables III and TV give a breakdown by vehicle of the percentage
change from the baseline tuned-up condition results.
Table V Illustrates what can be achieved by tuning a vehicle
to manufacturers' specifications. That is, an average of 9.0% improvement
was achieved by tuning up the "as received" rental vehicles to manufacturers'
specifications. Of these vehicles two cases out of three showed improvement
in fuel economy. Table V also shows the change in fuel economy resulting
from independent garage tampering on as-received vehicles. The data
illustrate that the improver.er.t vas greatest by tuning the vehicle to
manufacturers' specification. It should be noted that in the case of the
Fury II station wagon one plug was fouled as received and was replaced
by the garage. In the-case of the '73 Vega a new air cleaner and spark
plugs were installed as part of the garage modification.
Costs of the garage tampering averaged $22.86 with a range of
$12.50 to $37.50. The tampering modifications made by private
garages and their associated costs are listed in Appendix B.
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In no case were franchisee! new car dealers requested to perform the
tampering. The Clean Air Act forbids dealers from tampering.
The purpose of this program was to acquire technical information; the
program was not oriented toward determining the compliance of dealers with
Federal law. Therefore the garages that did tamper with the vehicles were
all independent organizations. They represent a cross-section of the
automobile service industry, and include corner gas stations, commercial
tune-up centers, as well as a garage that is widely advertised in the
Detroit metropolitan area as a specialist in the removal of emission
control devices.
Of significant note, the garage that advertised its expertise in
emission control removal modified two cars for EPA and in both cases was
unsuccessful in improving fuel econbmy. Of even greater interest may be
the fact that this organization knew that it was participating in the
EPA program. It was necessary to inform them of the EPA program because
their workload schedule was such that to get an anonymous test would
have required a .45-day delay. The failure of this organization to achieve
improved fuel economy may be attributable to the fact that it is oriented
toward improved performance (for example, acceleration and top speed).
This would indicate that application of a hot rodder's knowledge does
not insure achievement of improved fuel economy.
This study indicates that at the hands of highly skilled
emission control experts who have access to first-class tools and
equiprr.ont, average passenger vehicle fuel economy improvements of
approximately 7.0% can be obtained by tampering on '73-'74 cars equipped
with the most stringent emission controls. However, emissions of air
pollutants (HC, CO, and NOX) increased an average of approximately 65.9%,
20.9%, and 125.7% resspectively, through such readjustment. Lesser gains
in fuel economy would be expected from tampering with earlier model year
controlled vehicles (i.e., 1972 or earlier) which have less stringent
emission controls.
This study also suggests that independent garages in most
cases (70%) perform modifications in which fuel economy losses
result. The average change in fuel economy for thirteen cases of
garage tampering was a reduction of (-)3.5%. Only four cases out
of thirteen achieved even minor improved fuel economy. Thus, at
present it appears that the result of widespread independent garage
emission control system tampering would be expected to increase fuel
consumption, at significant cost in terms of increased air pollution.
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A further caution should be. made. These studies did not
address the potential damaging effects that tampering may have over
long-term mileage accumulation. It is known that engine maladjustments
and certain engine modifications can increase engine deterioration
rates. Thus fuel economy losses should become even greater with
mileage accumulation because of deleterious engine effects such as
increased spark plug fouling from enrichment, and from detonation or
preignition damage to valves, spark plugs, piston tops, and rings due
to improper ignition timing.
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TABLE I
Vehicle Selection and Modification Schedule
Vehicle
VW Type I
Chevy Impala
Vega
Ford SW
Ford Torino
Pinto
Duster
Nova
Vega
Fury II, SW
Year
'73.
'73
'74
'73
'73
'74
'73
'74
'73
'73
Engine
Disp.
96 CID
350 "
140 "
400 "
351 "
140 "
225 "
350 "
140 "
400 "
Carb.
IV
2V
IV
2V
2V
2V
IV
2V
IV
2V
Trans .
Std 4
At 3
At 3
At 3
At 3
At 3
At 3
At 3
At 3
At 3
Test
Inertia
2250 Ibs
4500 "
2750 "
5500 "
4500 "
2750 "
3500 "
4000 "
2750
5500
Access .
No
A/C
P/S
P/B
No
A/C
P/S
P/B
A/C
P/S
P/B
No
P/S
P/B
P/S
P/B
No
A/C
P/S
P/B
Approx.
Mileage
14,800
4,600
4,000
12,200
9,500
3,700
4,200
2,000
9,100
6,700
EPA
Mod
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Number
Garage
Mods
1
2
2 ,
1
2
1
1
1
1
1
Garage
F
A,D
. A,E
G
B,E
G
B
C
D
M
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TABLE II
Summary of Tampering Results on Fuel Economy/Emissions
Expressed as % Change from Baseline Tune-Up (Mfg's Spec)
Number of Number of Fuel
HC CO NOy Econ. Mods Tested Econ. Increases
Garage Mod '72 FTP 39.3 89.5 63.0 -3.5 13 4
EPA Mod '72 FTP 64.7 21.0 116.0 7.0 8 7
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TABLE III
Fuel Economy/Emissions Effects of Garage Tampering
Expressed as % Change from Basline Tune-up (Mfg's Spec)
Vehicle
'73 VW
'73 Impala
'73 Impala
'74 Vega
'74 Vega
'73 Ford SW
'73 Torino
'73 Torino
'74 Pinto
'73 Duster
'74 Nova
'73 Vega
'73 Fury SW
Garage
F
A
D
A
E
6
B
E
G
B
C
D
H
HC
35.5
92.0
91.0
-12.9
14.5
33.4
28.9
- 3.3
106.3
0.7
-17.7
10.0
90.4
CO
-11.7
116.9
317.0
- 7.3
29.9
191.5
69.8
4.3
66.9
38.8
-10.3
11.2
208.8
NOx
104.9
33.9
10.9
-21.3
0.4
603.4
50.6
5.7
61.7
3.2
1.6
72.4
49.0
Economy
2.1
- 9.1
-15.5
9.9
- 5.2
- 9.3
- 0.9
- 7.2
0.6
0.0
- 1.0
- 4.6
- 3.2
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TABLE IV
Fuel Economy/Emissions Effects of EPA Tampering
Expressed as
Vehicle
'73 VW
'73 Impala
'74 Vega
'73 Ford SW
'73 Torino
'74 Pinto
'73 Duster
'73 Fury SW
% Change
HC
41.5
39.6
61.6
169.3
63.6
146.9
-15.3
31.8
from Baseline Tune-up
CO
-15.8
59.9
-17.5
-37.2
83.7
48.7
-30.4
- 4.9
(Mfg's Spec)
NOX
2.1
107.5
151'. 3
442.1
38.7
87.9
26.2
58.0
Fuel
Economy
10.8
13.6
17.8
-5.7
6.3
2.2
9.0
6.5
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TABLE V
Summary of Effects of Tampering
on Three "As Received" Vehicles
Garage Mod
& Change from
"As Received
•
* 73 Fury SW
** 73 Vega
74 Nova
EPA Tune-up to
Mfg's spec
Z Change from
"As Received"
* 73 Fury SW
** 73 Vega
74 Nova
HC
CO
NOx
-85.6
29.6
0
-92.5
17.6
21.5
0.7
25.2
25.2
-67.4
12.6
39.6
71.4
11.2
-62.6
14.8
-35.5
-63.2
Economy
9.3
6.4
-2.9
18.2
11.5
-1.9
I/ Only one emission test on each car, as compared to
replicate tests for the other cars in test program.
* Plug fouled in #4 cylinder
** Air cleaner and plugs
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Appendix A
Discussion of Emission Control Systems
A very large number of factors influence the fuel economy of
passenger cars. These factors fall into the general areas of
vehicle operation (e.g., driver habits), ambient and road factors
(e.g,, temperature0 wind, quality of road surface)D and vehicle design
factors. To determine the difference in the fuel economy of two
automobiles, or two configurations of one automobile, it is necessary
to hold the vehicle operation, ambient, and road factors constant.
This is done during the Federal Emissions Test Procedure, as the test
is run using the same conditions in the closely controlled environment
of a chassis dynamometer test cell.
There are two key vehicle design factors that have been modified
by the vehicle manufacturers to achieve lower exhaust emissions:
spark timing, and carburetion (air/fuel ratio). Additionally, there
have been compression ratio reductions made to allow for the use of low
octane low lead fuel and to reduce NOx formation. These compression
ratio reductions have reduced fuel economy by an average of 3.5%.
Retarding of the spark advance from its optimum setting for
best fuel economy can reduce exhaust emissions within the cylinder
and outside of the cylinder. With retarded timing the combustion is
initiated later and the piston is further down the cylinder during the
main portion of the combustion event. This results in reduced exposure
to the high temperatures which are conducive to high oxides of nitrogen
(NOx) formation.
Retarded timing also results in increased exhaust temperature
because of the reduced expansion of the burned gases which result when the
combustion is intiated later in the cycle, The high exhaust temperature
promotes the further oxidation (combustion) of hydrocarbon (HC) and
carbon monoxide (CO) in the exhsus£ system,,
The carburetion required for minimum emissions depends .on the type
of control technique being used on the engine. Th® high oxygen availability
of lean mixtures results not only in low EC and CO ©missions, but also in
optimum fuel economy., Most current vehicles use the lean carburetion
approach to meet the ©mission standards. Alteration of carburetion on such
vehicles can result in reduced economy and higher ©missions.
i@ae systerns o however0 ueilia® control approaches in which rich
carburetion is used £© provide high HC and CO emissions £o the exhaust
manifold. These pollutants ©r© then burned in the sxhausfc with the help
of additional air pumped into the exhaust ports. The high emissions
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A-2
are required to provide sufficient "fuel" to the exhaust manifold so
that the temperatures generated are high enough for near-complete
combustion. This type of thermal after-treatment approach can.be
more effective than the lean carburetion approach as far as emissions
are concerned, but fuel economy suffers. An additional emissions
benefit of the rich carburetion approach is that it results in lower
NOX emissions due to the lower availability of oxygen during the
combustion in the cylinder.
Air pumps are sometimes employed to facilitate HC and GO
reductions in the exhaust of lean and rich burning engines by
increasing the oxygen availability. Air pumps have no significant
effect on fuel consumption because the small amount of power required
to drive the pump results in only a small (almost immeasurable) loss.
Exhaust gas recirculation (EGR) reduces NOX emissions by
reducing the oxygen concentration and flame temperature during
the combustion event. EGR can affect economy in several ways. With
well controlled EGR rates economy can be improved slightly because
the recirculated exhaust gas reduces the amount of throttling required
to run the engine and it also allows more spark advance to be used.
Because EGR reduces the octane requirement of an engine, a well-controlled
system can allow higher compression ratios. Most EGR systems on
current cars, however, do not take advantage of the octane improving
properties of recirculated exhaust gas nor are they well controlled.
If EGR rates are not properly controlled, or if they are excessive,
then fuel economy can suffer. High EGR rates slow down combustion
and occasionally cause misfire. These phenomena in themselves reduce
efficiency but even more loss can be incurred if richer carburetion is
used to help clear up the poor combustion quality.
Current (1973-74) automobiles incorporate the above mentioned
emission control techniques in a variety of ways. Most models
incorporate some spark retard, EGR, carburetion enleanment, and low
compression ratio in order to meet the emission standards.
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Appendix B
Garage A Neighborhood garage
" B Speed Shop (knew cars were from EPA)
" C Neighborhood garage
11 D Service station (knew cars were from EPA)
11 E Service station
" F Neighborhood garage - specializing in VW
" 6 Neighborhood garage
11 H Franchised tune-up center
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B-l
Garage Modification Description and Cost
I. 73 VW Type I
a) Garage F - $26.00
1) Adjust valves
2) Advance timing
3) Adjust carburetor to lean Idle
4) Change oil
II. 73 Chevrolet Impala
a) Garage A - $24.00
1) Change centrifugal advance springs
2) Adjust carburetor to rich Idle
3) Advance timing
4) Readjusted carburetor floats
b) Garage D - $16.00
1) Changed centrifugal advance springs
2) Advanced timing
3) Disconnect EGR
4) Disconnect air pump
5) Adjust carburetor to rich idle
III. 74 Vega
a) Garage A - $25.00
1) Installed lean main jet
2) Advance- timing
3) Set lean idle
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B-2
b) Garage E - $37.00
1) Disconnect EGR
2). Adjust idle to rich idle
IV. 73 Ford station wagon
a) Garage B - $12.50
1) Disconnect EGR
2) Full vacuum advance
3) Adjust carburetor to rich idle
4) Advance timing
V. 73 Torino
a) Garage B - $20.00
1) Remove spark delay valve
2) Change centrifugal advance springs
3) Advance timing
4) Set carburetor to rich idle
b) Garage E - $37.50
1) Disconnect EGR
2) Set carb to rich idle
VI. 74 Pinto
a) Garage G - $17.75
1) Disconnect air pump
2) Disconnect EGR
3) Advance timing
4) Full vacuum advance
5) Adjust carburetor to rich idle
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B-3
VII. 73 Duster
a) Garage B - $20.00
1) Advance timing
2) Went to full manifold vacuum advance
3) Adjust carburetor to rich idle
VIII. 74 Nova
a) Garage C - $15.00
1) Full vacuum advance
2) Advance timing
3) Adjust carburetor to lean idle
IX. 73 Vega
a) Garage D - $32.57
1) Replace spark plugs
2) Replace air cleaner
3) Retarded timing
4) Disconnect EGR
5) Adjust idle to lean idle
X. 73 Fury Station Wagon
a) Garage H - $13.90
1) Replace fouled plug
2) Tighten fuel line
3) Retune to specifications tuning (was performed
in error)
A) Disconnect EGR
5) Disconnect vacuum spark advance thermal override and
connected directly to ported carburetor vacuum
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B-4
6) Tune carburetor to richer idle and lower idle speed
7) Inverted air cleaner thereby disconnecting evaporative
and carburetor preheat systems.
Average Cost; $22.86
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C-l
Appendix C
Average
Average
Average
1972 FTP Results Fuel
1973 VW Type
HC
g/mi
2.35
2.84
2.60
4.91
2.44
3.68
aseline 41.5
3.47
3.56
3.52
aseline 35 . 5
Economy Tampering
I (96 CID)
CO C02
g/mi g/mi
Baseline
22.99 421.5
21.81 401.8
22.40 411.7
EPA Mod
16.40 358.6
21.29 384.5
18.85 371.6
-15.8 -9.7
Garage F Mod
20.68 417.3
18.87 393.8
19.78 405.6
-11.7 -1.5
NOX
g/mi
1.54
1.34
1.44
1.51
1.43
1.47
2.1
2.98
2.92
2.95
104.9
Eco
MPG
19.1
19.9
19.5
22.2
20.9
21.6
10.8
19.3
20.4
19.9
2.1
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C-2
Appendix C
Average
Average
Average
Average
1972 FTP Results Fuel Economy Tampering
1973 Chevrolet
HC
g/mi
3.29
2.56
2.80
2.88
4.38
3.65
4.02
seline 39.6
6.96
4.10
5.53
seline 92.0
5.77
5.23
5.50
seline 9.10
Impala (350 CID)
CO C02
g/mi g/nd.
Baseline
45.64 723.2
24.22 702.2
47.9 783.3
39.25 736.2
EPA Mod
64.45 603.7
61.10 592.4
62.78 598.1
59.9 -19.0
Garage A Mod
81.33 743.9
88.98 731.9
85.16 739.9
116.9 0.5
Garage D Mod
177.41 683.3
149.9 693.3
163.66 688.3
317.0 -6.5
NOX
B/mi
1.66
1.81
.92
1.46
3.16
2.90
3.03
107.5
2.09
1.81
1.95
33.6
1.41
1.83
1.62
10.9
Eco
MPG
11.0
11.9
10.2
11.0
12.3
12.7
12.5
13.6
9.9
10.0
10.0
-9.1
9.1
9.4
9.3
-15.5
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C-3
Appendix C
Average
Average
Average
Average
1972 FTP Results Fuel Economy Tampering
1974
HC
g/mi
1.65
1.53
1.81
1.91
1.72
2.44
3.11
2.78
iseline 61.6
1.45
1.63
1.41
1.50
iseline -12.9
1.99
1.95
1.97
iseline 14.5
Vega
CO C02
g/mi g/mi
Baseline
18.68 421.6
18.58 405.8
25.87 441.0
23.03 439.2
21.50 426.9
EPA Mod
18.89 349.73
16.59 365.45
17.74 357.6
-17.48 -16.2
Garage A Mod
19.50 385.9
22.05 403.5
18.28 371.1
19.94 386.8
-7.25 -9.4
Garage E Mod
30.23 431.6
25.60 447.9
27.92 439.7
29.86 2.9
NOX
g/mi
2.71
2.45
2.67
1.40
2.30
5.80
5.76
5.78
151.3
1.50
2.13
1.80
1.81
-21.3
2.08
2.55
2.31
0.4
Eco
MPG
19.6
20.2
18.2
18.4
19.1
22.9
22.1
22.5
17.8
21.1
20.0
21.9
21.0
9.9
18.3
17.9
18.1
-5.2
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C-4
Appendix C
Average
Average
Average
% Chg. from Baseline
1972 FTP Results
1973 Ford
HC
g/mi
3.01
2.85
2.93
8.18
7.6
7.89
eline 169.3
3.91
eline 33.4
Fuel Economy Tampering
SW (400 CID)
CO C02
g/mi g/mi
Baseline
25.06 807.1
16.87 754.5
20.96 780.8
EPA Mod
14.8 823.1
11.7 828.0
13.2 825.6
-37.2 5.7
Garage G Mod
61.10 792.5
191.5 1.5
N°mi
1.83
1.07
1.45
6.95
8.76
7.86
442.1
10.2
603.4
Eco
MPG
10.4
11.2
10.8
10.17
10.19
10.18
-5.74
9.8
-9.25
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C-5
Appendix C
Average
Average
Average
Average
1972 FTP Results Fuel
1973 Ford Torino
HC
g/mi
4.76
2.99
3.21
3.65
6.13
5.80
5.97
.seline 63.6
4.57
4.94
4.76
.seline 30.4
3.53
iseline -3.3
Economy Tampering
(351 W CID)
CO O>2
g/mi g/mi
Baseline
63.0 665.01
40.9 717.60
39.95 767.3
47.95 716.64
EPA Mod
91.0 597.56
85.2 594.26
88.1 595.91
83.7 -16.8
Garage B Mod
75.0 672.81
78.5 671.52
76.8 672.17
60.2 -6.2
Garage E Mod
50.0 757.28
4.3 5.7
NOX
g/mi
1.66
2.15
1.39
1.73
2.55
2.24
2.40
38.7
3.41
3.43
3.42
97.7
2.33
34.7
Eco
MPG
11.4
11.2
10.6
11.1
11.7
11.9
11.8
6.3
11.0
10.9
11.0
-00.9
10.3
-7.2
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C-6
Appendix C
1972 FTP Results Fuel Economy Tampering
1974 Ford Pinto (2.3 1)
CO C02 NOX Eco
g/mi g/mi g/mi MPG
Baseline
1.32 32.0 509.3 1.42 15.7
1.53 34.0 495.9 1.01 16.0
Average 1.43 33.0 502.6 1.22 15.9
EPA Mod
3.37 51.6 464.8 2.36 15.9
3.15 46.4 452.4 2.22 16.6
Average 3.26 49.1 458.6 2.29 16.3
% Chg. from Baseline 146.9 48.7 -8.8 87.9 2.2
Garage G Mod
2.97 55.3 454.2 2.17 16.1
2.92 54.8 464.0 1.77 15.9
Average 2.95 55.1 459.1 1.97 16.0
% Chg. from Baseline 106.3 66.9 -8.7% 61.7 0.6
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07
Appendix C
Stock Baseline
Average
Average
1972 FTP Results Fuel
1973 Duster
HC
g/mi
2.55
2.71
2.66
2.72
.seline 0.7
2.15
2.16
2.16
seline -15.3
Economy Tampering
(225 CID)
CO C02
g/mi g/mi
25.77 522.2
Garage B Mod
33.4 503.1
38.2 514.9
35.8 509.0
38.8 -2.5
EPA Mod
16.18 502.2
19.68 480.8
17.93 491.5
-30.4 -5.9
NOX
g/mi
3.70
3.31
3.85
3.58
3.2
5.22
4.13
4.67
26.2
Eco
MPG
15.5
15.7
15.2
15.5
0.0
16.6
17.1
16.9
9.0
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C-8*
Appendix C
1972 FTP Results Fuel
1973 Fury
HC
g/mi
3.11
4.10
% Chg. from Baseline 31.8
5.92
% Chg. from Baseline 90.4
Economy Tampering
II SW
CO C02 NOX
" E /mi £/ mi & /mi
Baseline
30.8 920.4 4.41
EPA Mod
29.3 838.1 6.97
-4.9 -8.9 58.0
Garage H Mod
95.1 814.5 6.57
208.8 -11.5 49.0
Eco
MPG
9.1
9.9
6.5
9.0
-3.2
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C-9
. Appendix C
1972 FTP Results—As Received Vehicles
HC CO NOX Eco
g/mi g/mi g/mi MPG
74 Nova
As Received
1.77 18.5 1.71 10.5
Garage C Mod
1.77 23.1 0.64 10.2
EPA-Spec. Tune
2.15 25.8 0.63 10.3
73 Vega
As Received
2.26 34.9 2.59 17.3
Garage D Mod
2.93 43.7 2.88 18.4
EPA-Spec. Tune
2.66 39.3 1.67 19.3
73 Fury III SW
As Received
41.3 94.4 3.84 7.7
Garage H Mod
5.92 95.1 6.58 9.0
EPA-Spec. Tune ;___
3.11 30.8 4.41 9.1
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C-10
Appendix C
Overall Average 72 FTP Results
HC CO NOX Eco
8/mi g/mi g/mi MPG
Baseline (spec, tune)
2.57 30.7 2.00 14.2
EPA Mod
4.23 37.1 4.31 15.2
Garage Mod
3.58 58.2 3.25 13.7
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