EPA-AA-IMS/81-15
COMPILATION OF INSPECTION/MAINTENANCE
FACTS AND FIGURES
June 1981
Jane Armstrong
Eugene Tierney
Inspection/Maintenance Staff
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
Revised July 1981
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INTRODUCTION
Since the passage of the 1977 Amendments to the Clean Air Act, a great
deal of information has been assembled about vehicle inspection and main-
tenance (l/M) programs. Laboratory studies, surveys, and investigations
of operating I/M programs have been conducted to quantify the costs and
benefits and to project the impact of these programs on air quality.
This report compiles and summarizes the latest technical information
available from these studies for the use of policy makers and planners.
The facts and figures in this report have been gathered from the tech-
nical reports referenced at the end of the document. Interested readers
are encouraged to obtain these reports for additional information.
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AIR POLLUTION
Carbon Monoxide
Carbon monoxide (CO) is a colorless, odorless, poisonous gas produced by
the incomplete burning of fuels. The primary source of CO emissions is
motor vehicles.
Carbon monoxide combines with hemoglobin and thereby reduces the amount
of oxygen normally carried in the blood. This condition is called hy-
poxia. Hypoxia can cause cardiovascular diseases, fetal abnormalities,
and central nervous system disorders which affect sleep, alertness, and
muscle coordination.[1]
In 1977, 62 of 105 urban areas with population over 200,000 exceeded the
health-related ambient air quality standard for carbon monoxide. The
most recent State Implementation Plan (SIP) revisions, which were
submitted to EPA in 1979, indicate that 39 major urban areas will
continue to exceed the CO standard beyond 1982.
AREAS PROJECTED TO EXCEED THE AIR QUALITY
STANDARD FOR CARBON MONOXIDE BEYOND 1982-
STANDARD
9 s*/.3
BridgeportCT
Los Angeles
Albuquerque
Chicago
Cleveland
Denver
Fresno
New York
Phoenix
Pittsburgh
Atlanta
Charlotte
La 3 Vegai
Louisville
San
Francisco
Boise
Colorado
Springs
Fort Collins
Tucson
Boston
Creeley CO
Hartford CT
Portland OR
Sacramento
Seattle
Springfield
WashinctonDC
Balcinore
Milwaukee
Nashville
Philadelphia
Salt Lake
-
Detroit
Xenphis
Providence
San Diego
Worcester
St. Louis
35-33 27-23 23-21 21-19 19-17 17-15.5 15.5-13
mg/a3
DATA COLLECTED FROM AIR QUALITY MONITORING SITES during the
period 1975 to 1977 were used by the States to project when
air quality standards would be attained. The urban areas
shown above had monitored ambient CO values ranging from one
and a half to four times the standard and are projected to
continue to exceed the standard beyond 1982.
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AIR POLLUTION
Ozone
Ozone (03), the main constituent of smog, is formed by the reaction of
hydrocarbons and oxides of nitrogen in the presence of sunlight. Ozone
precursors are emitted by both stationary and mobile sources.
Exposure to ozone can cause coughing, chest discomfort, and irritation of
the nose and throat. Ozone can also damage the cells that line the lung
walls and protect them from harmful bacteria. This can increase the
chances of contracting an infectious lung disease.[1] These harmful ef-
fects are especially pronounced in children, the aged and those with res-
piratory ailments.
In 1977, 103 of 105 major urban areas exceeded the health-related air
quality standard for ozone (0.08 parts per million). When the standard was
relaxed to 0.12 ppm in 1979, the. number of areas exceeding the standard be-
came 93. The 1979 SIP revisions indicate that 36 urban areas with over
200,000 population will continue to exceed the ozone standard beyond 1982.
AREAS PROJECTED TO EXCEED THE AIR QUALITY
STANDARD FOR OZONE BEYOND 1982
STANDARD
0.12 ppn
Los Angele'f
Chicago
Cleveland
Detroit
Houston
Milwaukee
Sew York
Cincinnati
Philadelphia
Pittsburgh
San Diego
Trenton
Wilmington
DE
Allentown/
Bethlehem
Louisville
St. Louis
Ventura CA
Washington
DC
Baltimore
Fresno
Providence
Sacramento
San
Francisco
Boston
Denver
Nashville
Portland OR
Salt Lake
Springfield
-
Bridgeport
hartford
New Haven
Phoenix
Worcester
.51
.32-. 23
.22
.21-T.191
.190-. 181
.180-. 16
.15-.13
DATA COLLECTED FROM AIR QUALITY MONITORING SITES during the
period 1975 to 1977 were used by the States to project when
air quality standards would be attained. The urban areas
shown above had monitored ambient ozone values ranging from
slightly above to over four times the standard and are
projected to continue to exceed the standard beyond 1982.
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THE NEED FOR INSPECTION AND MAINTENANCE
In an urban area, motor vehicles typically contribute 90% of the carbon
monoxide and 50% of the hydrocarbons; the latter combine with other pollu-
tants to form ozone.
The Federal Motor Vehicle Control Program (FMVCP) has operated since. 1968
to assure that cars are designed and built for lower emissions. Increa-
singly stringent emission standards for new cars have resulted in vehicles
which are capable of emitting less than 10% of the emissions of an uncon-
trolled, mid-1960's model. But the ability of the new car strategies (pro-
totype certification, assembly line testing, and recall of defective
designs) to reduce emissions depends on proper use and maintenance by vehi-
cle owners once the new cars .are put on the road.
Tests of thousands of typical vehicles, borrowed from their owners, show
that much of this emission reduction potential is being lost because of in-
adequate or improper maintenance.
PERCENT OF CARS ON THE ROAD WHICH FAIL
TO MEET EMISSION STANDARDS
e/i
Q
H
CO
o
2
M
g
W
o
X
W
W
CJ
t*J,
W
PH
CO
HC
60-701 of five year old
cars exceed standards
-30 40-501 of one year old
cars exceed standards
.20
-10
AGE
NEARLY HALF OF THE ONE YEAR OLD CARS
on the road exceed federal emission
standards and this increases with
the car's age. Most of the cars
fail to meet standards because of
improper maintenance and adjustments
by owners and mechanics after the
cars leave the factory.[2]
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THE NEED FOR INSPECTION AND MAINTENANCE
(continued)
Due to the poor emission performance of vehicles on the road, the
significant downward trend in emissions from motor vehicles expected as a
result of the FMVCP has not been fully realized. Inspection/Maintenance
(l/M) is a strategy which attempts to solve this problem by providing the
incentive for proper maintenance by car owners.
NATIONAL EMISSIONS OF CARBON MONOXIDE
AND HYDROCARBONS FROM MOTOR VEHICLES
HYDROCARBONS
CARBON MONOXIDE
Actual emissions
Actual emissions
emissions
if all cars \
net
standards.
missions
if all cars
net
standards.
1970
1975
19SO
1970
1975
1980
THE EMISSION REDUCTION POTENTIAL OF THE FEDE-
RAL MOTOR VEHICLE CONTROL PROGRAM IS NOT BEING
FULLY REALIZED. These graphs compare actual
on the road emissions (solid lines) with the
hypothetical emissions (dashed lines) which
would have resulted had all cars met federal
emission standards. The area between the
curves represents the emission reductions not
realized.[3]
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THE INSPECTION AND MAINTENANCE PROCESS
Motor vehicles undergo an annual emissions inspection, normally as a prere-
quisite to annual registration, sometimes in conjunction with an existing
safety inspection. The inspection may be performed at a licensed garage or
at facilities operated by the state or local government.
EMISSIONS TEST
PASS
The car is tested by sampling the
exhaust emissions while the car
is idling. High levels of mea-
sured pollution indicate the need
for maintenance.
70-80% of the cars
pass the test.
FAIL
20 to 30 percent of the cars fail
the test. Car owners are provided
with test results and diagnoses
which can help the mechanic per-
form more efficient repairs.
REPAIR
Normal, inexpensive repairs such
as a simple carburetor adjustment
are all that are usually necessary
to achieve lower emission levels
and improved fuel economy.
RETEST
The inspection is repeated to ver-
ify that the repairs have resulted
in lower emission levels.
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EMISSION REDUCTIONS FROM I/M
EPA has undertaken a study of the Portland, Oregon I/M program to determine
the costs and benefits associated with an operating program.
The study showed that the idle test used in most I/M programs properly
identifies vehicles with excessive emissions. A comparison using the com-
plex Federal Test Procedure shows emissions from cars failing the idle test
at the state operated inspection lanes are two to three times higher than
from those passing the test.
In the Portland study, those cars failing the state inspection test were
taken by their owners to private repair facilities where corrective
maintenance was performed. The maintenance resulted in each car passing
the state reinspection test and produced an emission reduction of over 40%,
bringing emissions close to the federal standards to which these cars were
originally certified. ....
EMISSION REDUCTIONS FROM CARS RECEIVING MAINTENANCE
IN EPA'S PORTLAND STUDY
HYDROCARBONS
42%
reduction
CARBON MONOXIDE
reduction
stan-
dard
BEFORE AFTER
BEFORE AFTER
ENGINE MAINTENANCE by Portland area mechanics to
vehicles failing the state inspection resulted in
a 42% reduction in hydrocarbon emissions and a 47%
reduction in carbon monoxide emissions .[4]
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EMISSION REDUCTIONS FROM I/M
(continued)
The Portland Study also followed a sample of cars throughout a full year to
determine whether the emission reductions following maintenance last.
Although emissions deteriorated following maintenance, the average
emissions of the Portland fleet were 20 percent lower for HC and 36 percent
lower for CO when compared to a similar fleet of vehicles in a nearby city
which does not have an I/M program.
AVERAGE EMISSION LEVELS OVER A YEAR
PERIOD FOR SIMILAR FLEETS OF VEHICLES IN
PORTLAND AND EUGENE, OREGON
HYDROCARBONS
CARBON MONOXIDE
vi a
Zr-l
e
CO --- .
CO tfi
i-* E
ei
NON-J/H CflSE
NON-I/M CBSE
36%
reduction
ONE YEA!.
ONE YEAR
EMISSION REDUCTIONS FROM I/M LAST for much of the following year.
The top curve shows the emissions, in grams per mile, of a fleet
of 1975 to 1977 model year vehicles in Eugene., Oregon a city which
does not require I/M. The curve shows the typical trend of emis-
sions increasing with age (in this case, one year). The bottom
curve presents the emissions of a similar fleet of vehicles in
Portland, Oregon, which requires I/M. The sharp drop in emissions
at the beginning of the one year period reflects the maintenance
received by the approximately 30% of the vehicles that failed the
inspection test. The emission levels over the following year in-
crease, but not sufficiently to reach the levels of the Eugene
cars. Over the one year following inspection, Portland vehicles
averaged 20% lower HC and 36% lower CO emissions. The initial
"gap" between the Eugene and Portland cars is attributed to a pre-
vious inspection and repair cycle undergone a year before by some
of the older Portland vehicles. Note that these curves represent
the entire fleet, including the 70% of vehicles that passed the
inspection and received no repair.[4]
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AIR QUALITY BENEFITS OF I/M
By reducing emissions from motor vehicles, ambient levels of pollution
should also be reduced. Supporting evidence comes from a variety of
sources.
Carbon Monoxide
The relationship between reductions in carbon monoxide (CO) emissions from
motor vehicles and improved ambient air quality for CO is well established.
In 1981, a statistical analysis of CO air quality data from Portland, Ore-
gon quantified the effect of the I/M program on ambient CO levels. The re-
searchers found that the I/M program produced reductions in ambient CO
levels which compared well with the predicted improvements based on
reductions in tailpipe emissions.
AMBIENT CO AIR QUALITY IMPROVEMENT
DUE TO I/M IN PORTLAND, OREGON
IMPROVEMENT
8-15%
10-19%
COMMENT
Observed ambient improve-
ment in 1976 and 1978
Adjusted to annual
inspection frequency
AMBIENT CO LEVELS IN PORTLAND, OREGON showed
an 8 to 15 percent improvement over what would
have occurred had there been no inspection
program. These improvements were observed in
1976 and 1978, the years when about 70% of the
fleet were inspected in Portland's biennial
program.[5] Adjusting these data to reflect
an annual inspection program results in a 10
to 19 percent improvement in ambient CO levels
due to I/M.
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AIR QUALITY BENEFITS OF I/M
Ozone
Ozone is produced in the presence of sunlight through the interaction of
non-methane hydrocarbons (HC), oxides of nitrogen and oxygen. Research
smog chamber studies have demonstrated that HC emission reductions reduce
ambient ozone levels. Air quality data from California show both hydro-
carbon and ozone reductions occurring simultaneously. This link between HC
reductions and lower ozone levels, along with data (such as from the Port-
land Study) indicating I/M's ability to reduce HC emissions from motor
vehicles, provides strong evidence that I/M will be effective in improving
air quality for ozone.
HYDROCARBON-AND OZONE REDUCTIONS
San Francisco (1967-1976)
HC reduced 25%
Ozone reduced 25%
Los Angeles (1967-1974)
HC reduced 18%
Ozone reduced 19%
ANALYSES OF AIR QUALITY and emis-
sion trends in California indi-
cate that changes in hydrocarbon
emissions are consistent with
changes in ambient levels of
ozone.[6,7]
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AN I/M PROGRAM TO SAVE FUEL
The same corrective maintenance which lowers tailpipe emissions can also
result in improved fuel economy. Studies show that the repair of 1981 and
later model year cars which have computer failures can result in fuel economy
improvements averaging 15 percent ($135 fuel savings per year). However, the
Portland study showed that the repair industry in Oregon does not achieve a
net fuel economy improvement from the pre-1981 failed cars.
The key to achieving fuel economy improvements is properly performed mainte-
nance. When Portland area mechanics were trained in proper diagnosis and
repair of high emitting vehicles, they were able to improve the fuel economy
of the pre-1981 failed cars.
Large fuel economy improvements can also come from proper tire inflation. The
average tire is 1.8 pounds per square inch (psi) underinflated. Fleetwide
fuel economy can be improved 1.1 percent if all tires are inflated to the
vehicle manufacturer's "soft-ride" specification (28 psi); a 3 percent -fuel
economy improvement can occur if tires are inflated to the tire manufacturer's
limit of 32 psi. An inspection program provides a good opportunity to achieve
this potential benefit.
ANNUAL FUEL ECONOMY BENEFITS PER INSPECTED VEHICLE
FROM THE OPTIMAL I/M PROGRAM
PROGRAM COMPONENTS
DOLLAR GAS NATIONWIDE GAS
SAVINGS SAVINGS SAVINGS
(million gallons)
Basic I/M Program
More Effective Test
Mechanic Training
Tire Pressure Checks
$2.74
$1.11
$4.18
$14.88
0.29%
0.12%
0.46%
1.59%
83.6
33.8
130.2
453.8
OPTIMAL PROGRAM: TOTAL $22.91
2.46%
701.4
An optimal I/M program would incorporate the most effective exhaust test
(identifying a greater number of 1981 and newer vehicles with computerized
fuel system failures), mechanics training, and tire pressure checks to
achieve the greatest fuel savings for the entire fleet. It is interesting
to note that a $14 fuel savings (61% of the maximum possible savings) will
exactly offset the total cost of the I/M program.[8]
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COST TO THE AUTOMOBILE OWNER
There are two costs to the auto owner associated with I/M: the inspection
fee and the repair cost. Each owner will pay an annual fee for inspection;
only those failing the inspection will incur repair costs. These repair
costs can be partially to completely . offset by fuel economy improvements
resulting from the maintenance performed.
Fees
Inspection fees in currently operating programs range from $2.50 to $17.
The fee is set to make the program self-supporting by covering both the
fixed and operating costs of the program including facilities, equipment
and administration. Fees for I/M programs beginning in 1983 are estimated
to be $8.00 to $10.
OPERATING PROGRAM INSPECTION FEES
Arizona $5.75
California $11.00
Nevada $11-17*
New Jersey $2.50
Oregon $5.00
Rhode Island $4.00°°
* Includes mandatory adjustment
00 Includes safety inspection
Repair Costs •
Between 15% and 30% of pre-1981 vehicles will fail an inspection and re-
quire repairs. The most common maintenance includes repair, replacement or
adjustment of the carburetor, spark plugs, timing, choke, dwell, idle speed
or air filter. Average repair costs reported from operating I/M programs
range from $17 to $30.
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COST TO THE AUTOMOBILE OWNER
(continued)
DISTRIBUTION OF REPAIR COSTS FOR FAILED
CARS IN EPA'S PORTLAND STUDY
CO
pi
w
£
o .
PERCENT
60
_50
.40
30
.20
-
1 1
<$5 $5-25 $26-50 $51-75 >$75
THE MAJORITY OF CARS in the Portland Study required only
minor tune-up work to pass the state inspection test.
The distribution of costs is skewed heavily to the low-
end with 50% of the sampled 1972-1977 vehicles incurring
costs of $14 or less. A small number of cars incurred
high maintenance costs, bringing up the mean of the sam-
ple to $29, but 90% of the cars were repaired for $70 or
less. Many I/M programs will limit the cost of required
repairs to under $75. [4]
Some 1981 and later model year cars will also require repair of ignition
problems, vacuum leaks, and tampering of some emission control components
with older cars. In addition, some of the newer cars will require repairs
of their computer controlled fuel metering systems. These repairs will
range from simply reconnecting a wire to a sensor or actuator to replacing
a sensor, an actuator, or the computer. Preliminary data from computer
controlled cars participating in California's I/M program indicate that the
average repair cost is likely to be approximately $30.[9]
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COST-EFFECTIVENESS OF I/M
The cost-effectiveness of an air pollution control strategy is the measure
of that strategy's cost relative to its ability to remove a particular pol-
lutant from the atmosphere. Cost-effectiveness estimates allow air quality
planners to evaluate and compare various strategies which might be imple-
mented to attain air quality standards. The cost-effectiveness of I/M is
estimated to be $581 per ton of hydrocarbons and $53 per ton of carbon'mon-
oxide reduced. This compares favorably with that of other stationary and
mobile source strategies for reducing emissions.[9]
I/M COST-EFFECTIVENESS OVER A FIVE YEAR PERIOD
(1983-1987)
ALLOCATED MASS REMOVED COST-
POLLUTANT I/M COST BY I/M EFFECTIVENESS
(million dol-lars) (tons) (dollars/ton)
Hydrocarbons 27.05 46,500 581
Carbon monoxide 27.05 512,600 53
I/M COST-EFFECTIVENESS WAS MODELED by having an example fleet of
one million vehicles participate for five years in a hypothetical
I/M program starting in 1983. The design of the hypothetical I/M
program was typical of programs now being implemented. Total
costs were determined by adding together repair costs and inspec-
tion costs for the five year period, then subtracting fuel
savings attributable to the program. Emission reductions were
obtained using MOBILE2 (EPA's model for predicting the emission
behavior of a fleet of vehicles with and without I/M). Because
most areas which are implementing I/M require reductions for both
hydrocarbons and carbon monoxide, the costs of the program have
been allocated equally to both pollutants.[9]
Minimum fuel savings attributable to a basic I/M program are included in
the cost effectiveness estimates given above. By enhancing the program to
achieve the greatest fuel economy improvement from the fleet of inspected
vehicles, it is possible to entirely offset the inspection and repair costs
and to realize a net savings.[8,9]
Planners must exercise caution in comparing cost-effectiveness values for
different control measures. The presence of air pollution control stra-
tegies with greater or lesser cost-effectiveness estimates than other stra-
tegies does not mean that there is a cut-off cost-effectiveness above which
no strategy is implemented. The size of the emission reductions available
from a strategy must also be considered. Although a strategy may have a
low cost-effectiveness estimate, it may not produce sufficient emission
reductions to allow attainment of air quality standards. I/M produces sub-
stantial emission reductions which contribute to expeditious attainment of
ambient air quality standards.
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PUBLIC OPINION ON AIR POLLUTION
Prior to 1970 and Earth Day, little public polling was done on environmental
issues. The number of public polls then increased until the early seventies,
when they became a regular occurrence. These polls have become very sophisti-
cated over the years, requiring individuals to make choices between environ-
mental protection and higher prices, more taxes, lower economic growth, and
higher unemployment.
PUBLIC ATTITUDES TOWARD ENVIRONMENTAL PROTECTION
"How serious ,is the air pollution problem?"
80%
Not serious1 Somewhat serious or very serious
Do you considejr yourself, active, sympathetic,
neutral or unsympathetic to the environmental
movement?" i
4%'
62%
Unsympathetic Active or sympathetic
THE LATEST NATIONAL SURVEY conducted by Re-
sources For The Future for the President's
Council on Environmental Quality demonstrates
that environmental protection enjoys continued
strong public backing. 1,576 adults were in-
terviewed in person between January and April
1980. [10]
A survey conducted in New York by Social Data Analysts for Hamilton Test
Systems suggests that urban area residents understand the connection bet-
ween automobiles and air pollution, and are willing to participate in
clean-up efforts. 500 New York City area residents were interviewed by
telephone in December 1980.
RESPONSE OF NEW YORK RESIDENTS TO QUESTIONS ON POLLUTION CONTROL
"What do you think are the major causes of air pollution
in the New York metropolitan area?"
Auto emissions 86%
Factories,light co. 56%
Trucks, buses, taxis 45%
"Do you think there should be laws making it illegal for
both business and individual citizens to pollute the
air?"
Yes 71%
No 14%
Business only 2%
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PUBLIC OPINION ON I/M
Several public polls have been conducted in areas where I/M programs are
either planned or operating. The results of some of these polls are pre-
sented below.
ARIZONA
(Arizona State University, Telephone survey N*=600, May 1979)
"Arizona has had an emission inspection program for cars and trucks for
about three years now. Do you personally feel the program should be kept
or repealed?"
Keep 58%
Repeal 42%
CALIFORNIA
(Gannet News Service, Telephone survey N=824, October 1980)
"California voters support the -idea -of smog and safety inspections for
their cars."
For 58%
Against 42%
NEW JERSEY
(New Jersey Motor Vehicle Inspection Study Commision, N=3245, February 1978)
"In the past, for economic reasons there have been recommendations to eli-
minate our mandatory vehicle inspection program. Do you agree or disagree?"
Keep 83%
Eliminate 16%
NEW YORK
(Social Data Analysts, Telephone survey N=500, December 1980)
"Starting in January 1981, cars will have to be inspected to find out whet-
her they are safe and if they are polluting the air too much. The cost of
the inspection will go up from $6 to $12. Do you think that this program
is a good idea?"
Yes 82%
No 17%
OHIO
(Cleveland Plain Dealer, Telephone survey N=5256, November 1980)
"Do you favor the proposal to require mandatory inspection of the exhaust
systems of all cars to curb pollution?"
Yes 52%
No 31%
RHODE ISLAND
(Rhode Island Lung Association, Telephone survey N=300, April 1979)
"Do you think that exhaust emission tests on automobiles are important?"
Yes 87%
No 8%
* N is the sample size
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I/M AND NEW TECHNOLOGY
Stringent new car emission standards for 1981 along with the need for bet-
ter fuel economy have brought about revolutionary changes in automobile en-
gine technologies. An issue that has been the subject of much discussion
is the need for and effectiveness of I/M for the 1981 and later fleet.
"NEW TECHNOLOGY" ENGINES AND EMISSION CONTROLS
Many new cars will employ a small
computer that receives signals
from a variety of sensors which
monitor key engine variables such
as coolant temperature, throttle
position, engine speed, and air/
fuel ratio. Then, the computer
automatically adjusts engine fun-
ctions bringing the engine into
optimal working condition. The
automatic adjustment also allows
the new catalysts to most effec-
tively convert all three automo-
bile pollutants to harmless by-
products.
-ELECTRONIC-
CARBURETOR. H
Tin
V»c»w*n Switch
Ct'bon Onilt.r
Data from California where new technology vehicles were introduced" in small
numbers as early as 1977 and then introduced fleetwide beginning in 1980,
reveal two important findings. First, the rate of emission control system
failure is low for the vehicles tested to date. Second, failures that do
occur result in emission levels up to ten times the emission standard for
those cars.
FRACTION OF NEW TECHNOLOGY FLEETWIDE EMISSIONS
CONTRIBUTED BY CARS WITH CONTROL SYSTEM FAILURES
CARBON MONOXIDE
HYDROCARBONS
BEFORE THEY ARE ONE YEAR OLD, 3 of every 100 vehicles
will have a computer control failure, and these 3
vehicles will account for one half of the new technology
fleetwide CO emissions and one third of the HC emissions.
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I/M AND NEW TECHNOLOGY
(continued)
I/M short tests are capable of identifying a significant portion of
the excess emissions from computer controlled fleets. On the basis
of limited data, repair of vehicles with computer problems results
in large emission reductions. Substantial fuel economy improvements
(15% on the average) are also associated with repair of failed com-
puter systems.
Traditional problems such as improper maintenance, misfueling, tam-
pering, and ignition related malfunctions will also be occurring in
the 1981 and later fleet. It is estimated that from 5% to 10% of
the fleet will fail an I/M test each year due to either the tra-
ditional causes or a computer failure.[11]
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REFERENCES
1. "Health effects of carbon monoxide and ozone," U.S. Environmental
Protection Agency, May 1981, EPA-AA-IMS/81-8A.
2. Cackette, Thomas, "The need for inspection and maintenance for current
and future motor vehicles," Society of Automotive Engineers, 790782.
3. Walsh, Michael P. , "Future trends in the control of emissions from
motor vehicles," Society of Automotive Engineers, 801359.
4. Rutherford, James A., "Update on EPA's study of the Oregon inspec-
tion/maintenance program," Presented at the 73rd annual APCA meeting,
June 24, 1980, APCA 80-1.2.
5. Tiao, G.C., "Statistical analysis of 'the effect of inspection and
maintenance on carbon monoxide air quality in Portland, Oregon."
May 15, 1981, EPA-460/3-81-016.
6. "Environmental Quality - 1977," The eighth annual report of the
Council on Environmental Quality, December 1977.
7. Trijonis, John, "Oxidant and precursor trends in the metropolitan Los
Angeles region," Atmospheric Environment, Volume 12, pages 1413-1420,
December, 1977.
8. Michael, R. Bruce, "Update on the fuel economy benefits of inspection
and maintenance programs," U.S. Environmental Protection Agency, '
April 1981, EPA-AA-IMS/81-10.
9. Darlington, Tom, "Update on the cost-effectiveness of inspection and
maintenance," U.S. Environmental Protection Agency, April 1981,
EPA-AA-IMS-81-9.
10. "Environmental Quality - 1980," the eleventh annual report of the
Council on Environmental Quality, December 1980.
11. Hughes, David W., "Inspection and maintenance for 1981 and later model
year passenger cars," Society of Automotive Engineers, 810830.
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