United States Environmental Protection Agency
Office of Air and Radiation
MOTOR VEHICLE TAMPERING SURVEY - 1984
September 1985
Robert Greco
FIELD OPERATIONS AND SUPPORT DIVISION
OFFICE OF MOBILE SOURCES
Washington, D.C.
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United States Environmental Protection Agency
Office of Air and Radiation
MOTOR VEHICLE TAMPERING SURVEY - 1984
September 1985
Robert Greco
FIELD OPERATIONS AND SUPPORT DIVISION
OFFICE OF MOBILE SOURCES
Washington, D.C.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY 1
Introduction 1
Conclusions 3
BACKGROUND 8
SURVEY METHODS 12
Site Descriptions 14
RESULTS 20
Vehicle Tampering 20
Site and Aggregate Totals 20
Tampering Trends 1978-1985 22
Types of Tampering 26
Vehicle Characteristics and Tampering 31
Vehicle Type 31
Vehicle Age 31
Manufacturer 40
Effect of I/M Programs on Tampering 43
Effect of Antitampering Programs on Tampering 47
Effectiveness of I/M-only vs. I/M + ATP 51
I/M Programs and Geographic Bias 53
Correlation Between Tampering and Idle Emissions ... 54
Fuel Switching 60
Fuel Switching Indicators and Overlap 60
Fuel Switching Rates 61
Fuel Switching by Vehicle Type 67
Fuel Switching and Vehicle Age 67
Catalyst Tampering and Fuel Switching 67
Gasoline Lead Concentrations . 69
APPENDICES
A. Relevant Portions of Clean Air Act 73
B. Survey and Data Recording Procedures 74
C. Emission Cutpoints for I/M Areas 88
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LIST OF. FIGURES
1. Component specific tampering rates:
1978-1984 surveys 4
2. Overall and Catalyst tampering by vehicle model
year - 1984 survey 7
3. Breakdown of surveyed vehicles by condition and
extent of tampering 21
4. Cumulative tampering prevalence as a function of
vehicle age for the 1978-1984 surveys 36
5. Cumulative catalyst tampering rates as a function
of vehicle age for the 1978-1984 surveys 37
6. Comparison of catalyst and overall tampering rates
with vehicle age as a function of survey year 39
7. Tampering rates by manufacturer - 1984 survey 41
8. Tampering prevalence by manufacturer for the
1978-1984 surveys 42
9. Comparison of data from 1984 survey sites that had
been surveyed previously (Figs. 9(a) and (b)) 52
10. Distribution of survey sample among tampering, fuel
switching, and idle test categories 55
11. Overlap of tampering and carburetor misadjustment
among conventionally carbureted vehicles - 1984
survey 57
12. Overlap of fuel switching indicators among unleaded
vehicles - 1984 survey 62
13. Overlap of catalyst tampering and fuel switching
among catalyst-equipped vehicles - 1984 survey 70
14. Lead concentrations in fuel sampled from misfueled
vehicles 71
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LIST OF TABLES
1. Tampering Prevalence by Vehicle Type for
Critical Control Components 7
2. 1984 Tampering Survey Summary 23
3. Classification of Vehicle Condition by Survey
Site 24
4. Trends in Vehicle Condition Classification 25
5. Comparison of 1984 Survey Sample to Actual
Nationwide Vehicle Fleet 25
6. Prevalence of Tampering by Component and Survey
Year 27
7. Component-Specific Tampering Rates (percent) by
Survey Location - 1984 Survey 29
8. Prevalence of Arguable Tampering by Component
and Survey Year 30
9. Tampering Prevalence (and Sample Size) by Model
Year and Vehicle Age at Time of Survey 32
10. Percentage of Catalyst Removal (and Sample Size)
among Catalyst-Equipped Vehicles by Model Year
and Vehicle Age at Time of Survey 33
11. Tampering Prevalence in I/M and non-I/M Areas 45
12. Tampering and Fuel Switching Prevalence by Vehicle
Type in I/M and non-I/M Areas 46
13. Catalytic Converter Tampering Prevalence by Vehicle
Type in I/M and non-I/M Areas - 1984 Survey 48
14. Tampering Rates (percent) for Components
Checked in I/M + ATP Areas - 1984 Survey 50
15. Idle Test Failure Rates (percent) by
Pollutant and Vehicle Condition 58
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16. Mean Idle Emissions by Vehicle Condition 58.
17. Fuel Switching Rates among Unleaded Vehicles by
Site and Indicator - 1984 Survey 63
18. Fuel Switching Prevalence among Unleaded Vehicles
in I/M and non-I/M Areas 65
19. Fuel Switching Rates among Unleaded Vehicles by
Indicator and Survey Year 65
20. Combined Tampering and Fuel Switching
Rates - 1984 Survey 66
21. Percentage of Fuel Switching (and Sample Size)
among Unleaded Vehicles by Model Year and Vehicle
Age at Time of Survey 68
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EXECUTIVE SUMMARY
INTRODUCTION
Under the direction of the Field Operations and Support
Division (FOSD) of the Environmental Protection Agency (EPA),
contract personnel from Colorado State University (CSU)
conducted a survey of light-duty motor vehicle tampering in
14 cities between April and October, 1984. The areas surveyed
and the total number of vehicles inspected are listed below.
Bakersfield, CA 320
Reno, NV 83
Dallas, TX 268
Birmingham, AL 300
Washington, DC 300
Cincinnati, OH 325
New Jersey 270
New York, NY 308
Boston, MA 286
Tampa, FL 327
St. Louis, MO 314
Portland, OR (two weeks) 603
El Paso, TX 334
Milwaukee, WI 388
TOTAL 4,426 vehicles
The objectives of this survey were:
1. T-O—make local measurements of the types and extent of
tampering and fuel switching.
2. To extend and update the knowledge gained from earlier
surveys on:
a. The rates of overall and component-specific
tampering and fuel switching.
b. The distribution of tampering by vehicle age,
type, manufacturer, and other variables of
interest.
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c. The correlation between tampering and vehicle
idle emissions.
d. The effect of vehicle inspection and maintenance
(I/M) programs and antitampering programs (ATPs)
on tampering and fuel switching.
To achieve these objectives, the inspection teams
visually examined emission control devices and measured the
idle hydrocarbon (HC) and carbon monoxide (CO) emissions of
each vehicle. To provide information on fuel switching, the
inspectors sampled gasoline from the tanks of vehicles (for
later laboratory lead analysis), tested for lead deposits in
tailpipes using Plumbtesmo® test paper, and checked the
integrity of the fuel filler inlet restrictors. Four cate-
gories were used to summarize the condition of the inspected
vehicles:
1. Tampered - at least one control device removed or
rendered inoperative
2. Arguably Tampered - possible but not clear-cut
tampering
3. Malfunctioning
4. Okay - all control devices present and apparently
operating properly
These brief but thorough inspections were performed with the
consent of the vehicle owners in a variety of settings more
fully detailed elsewhere in this report.
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CONCLUSIONS
The surveyed vehicles were classified as follows:
tampered - 22%; arguably tampered - 29%; malfunctioning - 4%;
okay - 46% (overall survey averages). The 22% tampering rate
is less than the 26% rate found in 1983 but greater than the
rates from the other large surveys of 1978, 1979, and 1982.
Since these surveys encompass different sites with different
vehicle age distributions, truck proportions, and other
characteristics, direct comparisons between surveys should be
made cautiously. This survey is also heavily weighted with
I/M + ATP areas, as is detailed later in this report. The
overall tampering rate for 1984 increases to 26% when the data
is weighted for the proportion of the national vehicle fleet
covered by I/M-only programs and I/M + ATPs. The tampering
rate for areas without an I/M program was 31%, while the rates
for I/M-only and I/M + ATP areas were 17% and 11%, respectively.
The component-specific rates for selected critical
components are shown in Figure 1. The results shown have not
been weighted to compensate for I/M program representation;
these rates probably underestimate the actual nationwide rates.
The tampering rates for catalytic converters and filler inlet
restrictors have increased steadily since 1978, while the
rates for other components fluctuated over the years. The
increasing tampering rates for catalytic converters and inlet
restrictors may be partly due to the increasing age of the
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ComponQnt or SystQm
Catalytic ConvertQr
Evaporative System
Air Pump System
Inlet Restrictor
PCV System
EGR System
1978
1979
1981
1982
1983
1984
132
132
Tamporing RatQ C%)
Figure 1. ComponQnt-specific tampering rates:
1978 - 1984 surveys.
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vehicles surveyed. Areas with I/M programs had a 3% catalyst
removal rate, while non-I/M areas had an 11% rate. Catalytic
converter removal increases HC and CO emissions by an average
of 475% and 425%, respectively.! For vehicles equipped with
three-way catalysts, substantial increases in NOX emissions
would also be expected to occur.
The fuel inlet restrictor and the exhaust gas recirculation
(EGR) system were the most frequently tampered components (10%).
EGR system tampering can increase NOX emissions by an average
of 175%. The EGR tampering rates in I/M and non-I/M areas were
7% and 14%, respectively.
Fuel Switching
Fuel switching, defined as the presence of any of the
three indicators^, was found in 14% of the unleaded vehicles
in the 1984 survey. This is the same rate found in the 1983
survey. The weighted fuel switching rate was 16%. The fuel
switching rates in non-I/M, I/M-only, and I/M + ATP areas
were 19%, 10%, and 8%, respectively. The pattern of overlap
among the three indicators is discussed in detail later in
this report. While the emissions impact of fuel switching
depends upon its duration and certain vehicle characteristics,
emission increases of 475% for HC and 425% for CO can easily
occur.
1 The emissions increases mentioned in this report are from a
study of three-way catalyst vehicles presented in Anti-Tampering
and Anti-Misfueling Programs to Reduce In-Use Emissions from
Motor Vehicles, EPA-AA-TTS-83-10, December 31, 1983.
2 The three fuel switching indicators are: a tampered fuel
filler inlet restrictor, a positive Plumbtesmo® tailpipe test,
and a gasoline lead concentration of more than 0.05 grams
per gallon.
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Aqe of Vehicle
A vehicle's age is clearly related to the probability
that it has been tampered, as has also been shown in previous
surveys. This is evident in Figure 2, which shows the rates
by model year for both overall tampering and catalyst removal.
Fluctuations in age-specific rates might be expected for
very old (1975) vehicles because of the smaller sample size
for that model year. These age-specific rates are investigated
more thoroughly later in this report.
Vehicle Types
The tampering rates for light-duty trucks was equal to or
higher than for automobiles in every tampering category, as
shown in Table 1. The difference in catalytic converter
tampering is particularly striking -- nearly three times as
prevalent for light-duty trucks as for passenger cars (14%
vs 5%).
I/M programs and tampering
The tampering rates in non-I/M areas were at least double
those in I/M areas for every critical component. Those areas
with I/M plus antitampering programs had lower tampering
rates than the I/M-only areas. The deterrent effect of I/M
programs, however, cannot be easily separated from the geograph-
ical influences on tampering rates. The differences in
program status of the various I/M areas must be considered
as well. These aspects are discussed more thoroughly later
in this report.
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Tampering Rate (Z)
50
10 -
Overall
Tampering
Catalyst
Tampering
1984 1983 1982 1981 1980 1979 1978 1977 1976 1975
Vehicle Model Year
Figure 2. Overall and catalyst tampering by
vehicle model year - 1984 survey.
TABLE 1
Tampering Prevalence by Vehicle Type for
Critical Control Components
Tampering Rate (%)
Component /System
Catalytic Converter
Filler Neck Restrictor
AIR System
PCV System
Evaporative Control
System
EGR System
OVERALL
Trucks
14
14
12
3
5
10
27
Cars
5
9
7
2
2
10
21
Overall
7
10
7
2
3
10
22
Fuel Switching
19
13
14
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BACKGROUND
Motor vehicle emissions in urban areas account for nearly
90% of the total carbon monoxide (CO) and airborne lead, over
30% of the hydrocarbons (HC) , and nearly 40% of the oxides of
nitrogen (NOX) emitted into the atmosphere. As a result, a major
focus of the nation's efforts to achieve compliance with clean
air standards has been the control of emissions from mobile
sources. In order to meet required emission standards, vehicle
manufacturers have, since 1968, installed a variety of pollution
control devices on new vehicles.
The 1977 amendments to the Clean Air Act (sections
203 (a) (3) (A) and (B), found in Appendix A) make it illegal for
automobile dealers, repair and service facilities, and fleet
operators.to disconnect or render inoperative emission control
devices or elements of design. Regulations issued under section
211 (c) of the Act (40 CFR Part 80) prohibit retailers and
wholesale purchaser-consumers from introducing or allowing the
introduction of leaded gasoline into vehicles labeled "unleaded
gasoline only". The EPA's Field Operations and Support Division
(FOSD), formerly the Mobile Source Enforcement Division (MSED),
is responsible for enforcing the tampering and misfueling
provisions of the Act.
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Before 1978, the EPA had data suggesting that tampering
with emission control devices and misfueling of "unleaded only"
vehicles with leaded gasoline was occurring. Variability in
the inspection procedures, however, prevented an accurate
assessment of the nature and extent of the tampering. As a
result, the Agency began conducting nationwide tampering
surveys of light-duty motor vehicles in 1978 to determine the
rates and types of tampering and fuel switching. These surveys
were conducted in 19781, 19792, 19813, 19824, and 19835,
either by FOSD directly or by EPA's National Enforcement
Investigations Center (NEIC) under the direction of FOSD.
Consistent inspection procedures were used throughout these
surveys to permit comparisons and identification of trends.
Motor Vehicle Tampering Survey (1978), U.S. Environmental
Protection Agency, Mobile Source Enforcement Division,
November 1978.
2 Motor Vehicle Tampering Survey (1979), U.S. Environmental
Protection Agency, National Enforcement Investigations
Center, May 1980, EPA-330/1-80-001.
3 Motor Vehicle Tampering Survey - 1981, Chattanooga, Tennessee
and Houston, Texas, U.S. Environmental Protection Agency,
National Enforcement Investigations Center, March 1982,
EPA-330/1-82-001.
4 Motor Vehicle Tampering Survey - 1982, U.S. Environmental
Protection Agency, National Enforcement Investigations
Center, April 1983, EPA-330/1-83-001.
5 Motor Vehicle Tampering Survey - 1983, U.S. Environmental
Protection Agency, Field Operations and Support Division,
August 1984, EPA-460/1-84-001.
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Th e uses for the tampering surveys have evolved since the
first survey was conducted in 1978. In 1983, the tampering
survey results for some locations were used to calculate credits
for State Implementation Plans (SIPs), the measures taken by
State and local governments to achieve ambient air quality
standards by reducing mobile source emissions. Data from the
surveys is also used in the default database for the Agency's
mobile source computer model (MOBILES) to estimate both the
emissions loading impact and the reductions that may be achieved
by various control programs. Sites for the surveys are chosen
in light of the need for data on specific areas considering
programs, as well as the continuing need to monitor the types
and extent of tampering and fuel switching nationwide.
The 1984 tampering survey was conducted for FOSD by the
National Center for Vehicle Emissions Control and Safety,
Colorado State University (CSU). The inspection procedures
used were consistent with those of previous surveys. The
objectives of this survey were:
1. To make local measurements of the types and extent of
tampering and fuel switching.
2. To extend and update the knowledge gained from earlier
surveys on:
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a. the rates of overall and component-specific
tampering and fuel switching.
b. the distribution of tampering by vehicle age,
type, manufacturer, and other variables of
interest.
c. the correlation between tampering and vehicle
idle emissions.
d. the effect of vehicle inspection and maintenance
(I/M) programs and antitampering programs (ATPs)
on tampering and fuel-switching rates.
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SURVEY METHODS
The 1984 tampering survey was conducted in 14 cities between
April and October, 1984. A goal of inspecting 300 vehicles in
each location was established to ensure a statistically meaning-
ful database; 4,426 total vehicles were actually inspected.
The mix of vehicles inspected was assumed to be a self-weighting
sample, and no attempt was made to approximate the national
vehicle mix.
Each inspection team consisted of at least four members:
three CSU personnel, one or two EPA representatives, and fre-
quently a state or local agency representative. The CSU personnel,
assisted by the state or local person, performed the actual
inspections, while the EPA representative(s) supervised the survey.
Each vehicle inspection included the following:
1. basic vehicle identification data recorded (year,
make, model)
2. all emission control systems checked
3. idle HC and CO emissions measured
4. fuel sample collected from unleaded-only vehicles for
lead analysis.
5. tailpipe tested for lead deposits using Plumbtesmo®^
test paper
6. integrity of fuel inlet restrictor checked
6 Plumbtesmo® is a registered trademark, and appears hereafter
without the ®. It is manufactured by Machery-Nagel, Duren, W.
Germany, and marketed by Gallard-Schlesinger Chemical Corp.,
Carle Place, New York.
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Th e inspection and recording procedures are detailed in
Appendix B. The survey database has been reviewed by CSU,
EPA, and the automotive manufacturers to ensure its accuracy.
The survey included only 1975 and newer light-duty cars
and trucks fueled with gasoline. For the purposes of the
tampering surveys, a vehicle is considered to be "unleaded"
if a dash label, tank label, or filler inlet restrictor
is observed at the time of the inspection. A vehicle's
designation as "unleaded" or "leaded" may be changed upon
subsequent review of the data. Fuel switching rates are
thus calculated based only on the unleaded vehicles surveyed.
Similarly, tampering rates for specific components are based
only on the vehicles originally equipped with the component.
The inspections were performed with the consent of the
vehicle owners at either roadside pullovers or inspection
stations. The survey was designed to minimize the refusal
rate of potential survey participants. A high refusal rate -
increases the uncertainty in the data gathered, and indivi-
duals who have tampered with or misfueled their vehicles are
less likely to allow their vehicles to be surveyed. The
overall refusal rate was relatively low (8%), but some
survey sites had very high refusal rates (see below). The
tampering and misfueling rates at these particular locations
might be significantly higher than reported here. A brief
description of each survey site follows.
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Bakersfield, California - Roadside Pullovers
Dates: April 2-5, 1984
Vehicles Surveyed: 320
Fuel Samples: 184
Refusal Rate: 2%
Tampering Rate: 31%
Misfueling Rate: 14%
The California Highway Patrol provided an officer to
stop potential survey participants, and the inspectors
solicited permission to conduct the inspections. Locations
for pullovers were changed daily.
Reno, Nevada - Inspection Stations
Dates: April 9-13, 1984
Vehicles Surveyed: 83
Fuel Samples: 37
Refusal Rate: 6%
Tampering Rate: 31%
Misfueling rate 22%
The Reno survey was conducted at the Reno DMV office and
at privately-owned I/M inspection stations. Low vehicle
volume at the I/M stations during the middle of the month led
to the small survey sample.
Dallas, Texas - Roadside Pullovers
Dates: April 30 - May 4, 1984
Vehicles Surveyed: 268
Fuel Samples: 204
Refusal Rate: 29%
Tampering Rate: 28%
Misfueling Rate: 18%
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Th e Texas Department of .Public Safety (TOPS) provided
officers to stop potential survey participants. The survey
was conducted in conjunction with a TOPS driver's license and
insurance card check, which could have increased the refusal
rate. Survey locations were changed daily.
Birmingham, Alabama - Roadside Pullovers
Dates: May 7-11, 1984
Vehicles Surveyed: 300
Fuel Samples: 162
Refusal Rate: 4%
Tampering Rate: 32%
Misfueling Rate: 25%
Roadside pullovers were conducted with the help of local
law enforcement officers of municipalities in the Birmingham
area. Inspection locations were changed daily and included
Birmingham (three days), Hoover, and Homewood.
Washington, D.C. - Inspection Stations
Dates: May 14 - 18, 1984
Vehicles Surveyed: 300
Fuel Samples: 213
Refusal Rate: 12%
Tampering Rate: 23%
Misfueling Rate: 10%
The Washington, D.C. survey was conducted at two
centralized I/M stations (three days at one location and two
days at the other).
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Cincinnati, Ohio - Roadside Pullovers
Dates: May 21-25, 1984
Vehicles Surveyed: 325
Fuel Samples: 273
Refusal Rate: 12%
Tampering Rate: 28%
Misfueling Rate: 12%
The roadside pullovers were conducted with the help of
Ohio State Highway Patrol officers throughout the greater
Cincinnati area. Some participants actually sought out the
survey as a result of extensive press coverage both prior
to and during the survey, possibly resulting in an
underestimation of tampering and misfueling rates.
New Jersey - Roadside Pullovers and Inspection Stations
Dates: June 18-22, 1984
Vehicles Surveyed: 270
Fuel Samples: 155
Refusal Rate: 3%
Tampering Rate: 16%
Misfueling Rate: 8%
The New Jersey survey was conducted, in conjunction with
a Department of Motor Vehicles' police pullover, over four days
in the northeastern part of the state. On the remaining day,
the survey was conducted at a State inspection station in
Newark.
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New York City, New York - Roadside Pullovers
Dates: June 25-29, 1984 '
Vehicles Surveyed: 308
Fuel Samples: 187
Refusal Rate: 6%
Tampering Rate: 16%
Misfueling Rate: 13%
The New York City survey was conducted with the help of
the New York Police Department at five different locations in
the borough of Queens.
Boston, Massachusetts - Roadside Pullovers
Dates: July 9-13, 1984
Vehicles Surveyed: 286
Fuel Samples: 208
Refusal Rate: 5%
Tampering Rate: 15%
Misfueling Rate: 9%
The Boston survey was conducted with the help of the
Massachusetts Registry of Motor Vehicles Police at five
locations in the greater Boston area.
Tampa, Florida - Roadside Pullovers
Dates: July 23-27, 1984
Vehicles Surveyed: 327
Fuel Samples: 280
Refusal Rate: 3%
Tampering Rate: 38%
Misfueling Rate: 23%
The Tampa survey was conducted with the help of the
Florida State Police at five locations in the greater Tampa
area.
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St. Louis, Missouri - Roadside Pullovers
Dates: July 30 - August 3, 1984
Vehicles Surveyed: 314
Fuel Samples: 264
Refusal Rate: 13%
Tampering Rate: 14%
Misfueling Rate: 10%
The St. Louis survey was conducted with the help of the
Missouri State Highway Patrol at five locations in the greater
St. Louis area.
Portland, Oregon - Inspection Stations and Roadside Pullovers
Dates: August 14-24, 1984
Vehicles Surveyed: 394/209?
Fuel Samples: 245/148
Refusal Rate: 3%/0%
Tampering Rate: 10%/4%
Misfueling Rate: 8%/l%
• The Portland survey lasted two weeks and was divided
into two parts . Seven days were used to survey vehicles at
inspection stations in the Portland area (four different
locations). The remaining two days were used to survey
vehicles by roadside pullover, with the assistance of state
and local police.
El Paso, Texas - Roadside Pullovers
Dates: September 10-14, 1984
Vehicles Surveyed: 334
Fuel Samples: 259
Refusal Rate: 6%
Tampering Rate: 30%
Misfueling Rate: 23%
7 Inspection Stations/Roadside Pullovers
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Th e El Paso survey was conducted with the help of the
El Paso Police Department at five different locations in the
greater El Paso area. A number of vehicles registered in
Mexico were also surveyed, but have not been included in El
Paso's rates.
Milwaukee, Wisconsin - Inspection Stations
Dates: October 1-5, 1984
Vehicles Surveyed: 388
Fuel Samples: 295
Refusal Rate: 26%
Tampering Rate: 11%
Misfueling Rate: 7%
The Milwaukee survey was conducted at four centralized
I/M stations in the Milwaukee area. The vehicles were surveyed
at the exit of the inspection station on four days, and at the
entrance to the station on one day. The refusal rate was
significantly lower when the vehicles were surveyed at the
entrance to the station.
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RESULTS
A. VEHICLE TAMPERING
1. Site and Aggregate Totals
The vehicles surveyed have been classified into four
categories established by previous surveys: tampered,
arguably tampered, malfunctioning, and okay. Each vehicle
was classified by the worst state of any component in the
vehicle. For example, a vehicle would be classified as
"tampered" if any one component had been tampered, even if
all other components were functioning properly. A vehicle
classified as "okay" must have all observed components
functioning properly!. -p^e criteria used for component
classification are presented in Appendix B.
The proportion of inspected vehicles with at least one
tampered component was 22%. More than half of the vehicles
surveyed displayed some form of malfunction, arguable
tampering, or clear tampering of emission control components
The specific distribution of surveyed vehicles among these
categories is depicted in Figure 3.
The frequency distribution of tampering instances for
those vehicles classified as "tampered" is also shown in
Figure 3. Nearly half of the tampered vehicles had multiple
components tampered, and 13% had four or more instances of
tampering.
1 An "okay" vehicle, however, may still be classified as
fuel switched (see section B.I., Fuel Switching Indicators
and Overlap of this report).
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Arguably Tampered
Malfunctioning
Tampered
Okay
four or more (13%)
three (10%)
-two (24%)
rone (53%)
Condition of Surveyed Vehicles
Number of Tampered Components
Figure 3. Breakdown of surveyed vehicles by
condition and extent of tampering.
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Tables 2 and 3 summarize the 1984 survey data by site.
Table 2 is a general survey summary, while Table 3 shows
the vehicle condition classification by site. Unlike the
1983 survey, the overall tampering rates in 1984 vary
considerably from site to site. This can be attributed to
the variety of I/M-only and I/M + ATPs covered by this
survey.
Table 2 also contains the refusal rate at each survey
site. While the overall refusal rate for the survey was
relatively low (8%), five survey sites had refusal rates
exceeding 10%. The actual tampering rates at these sites
were probably higher than is reported here, since individuals
who tamper with or misfuel their vehicles are less likely
to allow their vehicles to be .surveyed.
2. Tampering Trends 1978-1984
Table 4 shows the overall rates found in each of the
past five surveys. The percentage of okay vehicles in
1984 (46%) is higher than in any previous survey. It also
appears that the tampering rate has declined to 22% from
the 26% rate found in 1983. Such direct comparisons between
survey years, however, are not entirely appropriate. The
surveys, for example, covered different sites, and had
different age and car/truck distributions. More importantly,
because of the 1984 survey's specific goals, it greatly
overrepresents the percentage of the national vehicle
fleet under I/M + ATP (see Table 5). I/M + ATP areas
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TABLE 2
1984 Tampering Survey Summary
Survey Number of
Location Vehicles
Bakersfield, CA
Reno, NV
Dallas, TX
Birmingham, AL
Washington, DC
Cincinnati, OH
New Jersey
New York, NY
Boston, MA
Tampa , FL
St. Louis, MO
Portland, OR***
Portland, OR
El Paso, TX
Milwaukee, WI
320
83
268
300
300
325
270
308
286
327
314
394
209
334
388
Tampering
Rate (%)
31
31
28
32
23
28
16
16
15
38
14
10
4
30
11
Misfueling Survey
Rate (%) Type*
14
22
18
25
10
12
8
13
9
23
10
8
1
23
7
R
D
R
R
C
R
R, C**
R
R
R
R
C
R
R
C
Refusal
Rate (%)
2
6
29
4
12
12
3
6
5
3
13
3
0
6
26
TOTAL
4,426
22
14
*R = roadside pullovers, C = centralized I/M stations,
D = decentralized I/M stations
**four days roadside, one day centralized I/M station
***
survey was conducted for two weeks in Portland
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TABLE 3
Classification of Vehicle Condition by Survey Site
Tampered Arguably Malfunctioning Okay
Survey Site
Bakersfield, CA
Reno, NV
Dallas, TX*
Birmingham, AL
Washington, DC
Cincinnati, OH
New Jersey
New York, NY
Boston, MA
Tampa , FL
St. Louis, MO
Portland, OR**
Portland, OR***
El Paso, TX
Milwaukee, WI
(%)
31
31
28
32
23
28
16
16
15
38
14
10
4
30
11
Tampered (%")
11
18
26
20
34
22
23
25
19
35
25
47
33
31
43
(%)
3
0
7
6
5
6
3
3
12
1
6
2
2
1
2
(%)
54
51
39
41
37
44
59
56
54
26
56
40
61
37
45
OVERALL 22 29 4 46
*The rates do not total 100% for some sites because of rounding
**I/M Stations
***Roadside Pullovers
-------
-25-
TABLE 4
Trends in Vehicle Condition Classification
Survey
Year
1978
1979
1981*
1982
1983
1984
Tampered
(%)
19
18
14
17
25
22
Arguably
Tampered(%)
48
47
45
38
30
29
Ma If unct ioning
(%)
2
2
3
1
3
4
Okay
(%)
31
33
38
44
42
46
*Because the 1981 survey involved only two sites and a very
limited sample size, these results may exhibit more variance
than the other larger surveys.
TABLE 5
Comparison of 1984 Survey Sample to Actual Nationwide
Vehicle Fleet
Program
Type
non-I/M
I/M only
I/M + ATP
Percentage within Approx. Percentage of
Survey Sample (%) Nationwide Fleet (%)**
42
31
27
66
27
7
** Based on 1980 population data from the U.S. Census Bureau,
-------
-26-
comprised 27% of the survey sample (half of which came from
Portland alone), while only approximately 7% of the national
vehicle fleet were under such programs. Since vehicles in
I/M and I/M + ATP areas traditionally have lower tampering
rates, the 1984 survey probably underestimates the extent of
tampering nationwide.
This discrepancy can be compensated for by applying a
weighting factor to the tampering rates found under each
program type. This causes the overall 1984 tampering rate
to increase from 22% to 26%. Applying weighting factors to
all the previous surveys would be difficult, since some
surveys contained no I/M areas. For the sake of clarity,
only the actual, unweighted rates found during the surveys
will be reported. Useful comparisons, however, can still
be made between program types within a given year (e.g., I/M
vs. non-I/M) or between the same program type in different
years (e.g., non-I/M in 1983 and 1984).
3. Types of Tampering
The tampering rates for specific emission control
components and systems for the various survey years are
presented in Table 6. The component-specific tampering
rates for the 1984 survey are presented by survey site in
-------
-27-
TABLE 6
Prevalence of Tampering by Component, and Survey Year
Survey Year
Component /System
Catalytic Converter
Filler Neck
Restrictor
Air Pump System
Air Pump Belt
Air Pump/Valve
Aspirator**
PCV System
Evaporative
Control System
EGR System
EGR Control Valve
EGR Sensor
Heated Air Intake
Vacuum Spark
1978
1%
3
7
6
3
***
3
3
13
12
5
1
11
1979
1%
4
5
4
2
2
3
2
10
5
7
1
2
1981*
4%
6
4
4
4
0
2
2
5
5
5
0
1
1982
4%
6
5
5
4
1
3
2
10
7
7
1
0
1983
7%
7
7
7
3
1
5
5
13
9
12
1
1
1984
7%
10
7
7
4
1
2
3
. 10
7
6
1
5
Retard
Idle Stop 1100
Solenoid
*The 1981 survey was of limited scope, covering only two
sites and 399 vehicles.
**Vehicles with aspirated air systems are not equipped with
other listed air-injection components, nor do conventional
systems include aspirators.
***Aspirators were not checked during the 1978 survey.
-------
-28-
Table 7. The arguable tampering percentages by component
for the 1978-1984 surveys are presented in Table 8. Only
those vehicles originally equipped with a particular
component are considered when computing the tampering or
arguable tampering rate for that component. The heated
air intake was the only component that could be classified
as either tampered or arguably tampered, based on its
condition in a surveyed vehicle (see Appendix B).
Table 6 shows that tampering with the filler inlet
restrictor and vacuum spark retard has increased since the
1983 survey. Tampering rates for other components have
remained unchanged or have declined since the 1983 survey,
but have generally remained higher than the rates found in
1982 and earlier surveys. As was mentioned previously,
the 1984 data underestimates the nationwide tampering
rates because of the overrepresentation of I/M •+• ATP
areas in the survey.
Table 7 shows the wide variation in tampering rates
for any given component from site to site. Inlet restrictor
tampering, for example, ranged from 1% in Portland (roadside
check) to 19% in Birmingham. This range is partly due to
the effectiveness of I/M and antitampering programs, as
will be investigated later in this report.
-------
TABLE 7
Cortponent-Specific Tarrpering Rates (percent) by Survey Location - 1984 Survey
Emission Control Component or System
Survey
Location
Bakersfield, CA
Reno, NV
Dallas, TX
Birmingham, AL
Washington, DC
Cincinnati, OH
New Jersey
New York, NY
Boston, MA
Tampa, FL
St. Louis, MO
Portland, OR*
Portland, OR**
El Paso, TX
Milwaukee, WI
OVERALL
Catalytic
Converter
. 8
13
10
16
1
8
5
4
3
13
5
2
1
11
2
7
Inlet
Restrictor
11
15
12
19
9
8
5
2
5
17
7
6
1
17
5
10
Air Purrp
System
10
12
8
14
7
8
3
6
4
14
5
1
0
16
3
7
PCV
System
3
4
5
1
1
3
1
0
2
1
1
1
0
7
1
2
EGR Evaporative
System System
18
20
9
14
14
17
11
10
4
17
4
3
2
11
3
10
4
6
5
5
1
3
1
1
3
6
1
1
0
5
1
3
Any
Component
31
31
28
32
23
28
16
16
15
38
14
10
4
30
11
22
I
NJ
*I/M Stations
**Roadside Pullovers
-------
-30-
TABLE 8
Prevalence of Arguable Tampering by Component
and Survey Year
Survey
Year
1978
1979
1981
1982
1983
1984
Limiter
Cap
65%
62
83
54
54
49
Fuel Tank
Cap
0%
1
1
2
3
1
Tank
Label
5%
4
4
4
9
12
Dash
Label
1%
1
0
1
1
3
Heated Air
Intake
9%
8
9
6
14
8
-------
-31-
Table 8 shows that idle limiter caps remain the item
arguably tampered most frequently (49%). The arguable
tampering rate for limiter caps, however, was lower in
1984 than in any previous survey. The tank label and dash
label were removed more in 1984 than in previous surveys,
and the heated air intake showed a lower but still significant
arguable tampering rate.
4. Vehicle Characteristics and Tampering
The next section of this report investigates the impact
on tampering of three vehicle characteristics: type (car
or truck), age, and manufacturer.
Vehicle Type. The tampering prevalence for light duty
trucks was higher than for automobiles, as was mentioned
previously (Table 1). The tampering rate for each emissions
component on trucks was equal to or greater than on passenger
cars, continuing the pattern observed in previous surveys.
The catalytic converter tampering rate for trucks was nearly
three times that for automobiles (14% vs. 5%). The fuel
switching rate for trucks (19%) was also considerably higher
than for automobiles (13%).
Vehicle Age. Table 9 correlates vehicle age and model
year with tampering prevalence for the 1978-1984 surveys.
Catalytic converter removal rates are similarly related to
vehicle age and model year in Table 10. The results from
any given survey are entered diagonally in each table.
-------
TABLE 9
Tampering Percentage (and Sample Size) by Model Year and Vehicle Age at Time of Survey
Model
Year
First
Second
Third
Fourth
Year of Vehicle Life
Fifth Sixth Seventh Eighth
Ninth
Tenth
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1(462)
7(182)
1(250)
2(57)
6(371)
7(298)
4(471)
4(226)
7(448)
5(63)
14(502)
10(457)
7(466)
13(206)
9(454)
9(59)
15(476)
18(395)
15(458)
15(211)
18(477)
15(79)
19(374)
22(274)
18(516)
31(288)
21(430)
21(66)
22(271)
33(276)
28(503)
39(238)
26(316)
29(52)
27(242)
32(253)
34(559)
44(190)
26(317)
32(22)
36(251)
41(408)
40(171)
37(183)
39(385)
55(89) 46(197)
OJ
to
I
-------
TABLE 10
Percentage of Catalyst Removal (and Sample Size)
among Catalyst-equipped Vehicles by Model Year and Vehicle Age at Time of Survey
MDdel
Year
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
First
0(462)*
1(179)
0(250)
0(57)
0(326)
0(291)
Second
2(471)
1(225)
2(441)
2(61)
0(445)
1(417)
Third
2(465)
5(204)
2(428)
4(55)
1(417)
2(377)
Year of Vehicle Life
Fourth Fifth Sixth Seventh Eighth Ninth Tenth
6(457)
3(200) 6(487)
6(429) 12(252) 10(455)
0(71) 4(362) 8(213) 8(486)
2(59) 2(271) 11(166) 14(357)
2(305) 10(48) 6(257) 12(139) 12(314)
2(242) 2(204) 26(19) 12(139) 23(75) 16(174)
*Tampering rates have been rounded to the nearest whole percent. A zero does not necessarily indicate
a total absence of tampering, but rather a level of tampering that rounded to zero.
-------
-34-
Th e results in Tables 9 and.1O indicate that vehicle tampering
rates increase directly with vehicle age. Examining Table
9 diagonally (by survey) shows a fairly linear increase in
the tampering rate with vehicle age for each survey. In
the 1984 survey, for example, the tampering rate increases
from 1% for first year vehicles to 46% among the 1975
vehicles surveyed. Table 10 shows a similar, though less
pronounced, increase in catalyst removal. Examining these
tables in this manner has the advantage of comparing data
collected during one survey in one set of locations, but
ignores the possible effects of model year differences
(i.e., technology) on tampering.
Two additional ways of analyzing Tables 9 and 10 address
the impact of model year on tampering rates. Analyzing the
tables horizontally (holding the model year constant)
provides a look at the tampering rates over time for the
vehicles of a particular model year. This approach shows
the same distinct increase in tampering with vehicle age
for all model years since 1975. (The 1974 and 1973 data
sets are too small to permit any conclusions.) For example,
the tampering incidence for 1979 vehicles increased from 6%
in their first year to 28% by their sixth year of use.
This increase in tampering with vehicle age also seems to
lessen once the vehicles of a model year are five years old
or more, with.the tampering rates leveling off at higher
-------
-35-
levels in older model years. -This type of analysis involves
observations made from different survey sites at different
times; nevertheless/ the relationship between tampering rate
and vehicle age is readily apparent.
Tables 9 and 10 can also be analyzed vertically (holding
vehicle age constant), which provides a look at the tampering
rates for different model year vehicles of the same age.
This approach suggests that improvements in automotive
technology, such as closed loop emission control systems,
have not significantly affected overall tampering rates.
A 1983 vehicle, for example, was as tamper-prone as a
1978 vehicle when both were new (first year of use). A
similar vertical analysis of Table 10 shows that catalytic
converters are as susceptible to tampering on new vehicles
as on older ones at a given vehicle age. Analyzing Tables 9
and 10 vertically introduces the same variability as the
horizontal analysis, which might obscure any slight decrease
in tampering resulting from improved technology.
The influence of vehicle age on tampering can
be more clearly seen when the data in Tables 9 and 10 is
presented graphically. Figures 4 and 5 plot the overall
and catalyst tampering rate, respectively, as a function of
vehicle age for the 1978-1984 surveys. This is equivalent
to the diagonal method of analysis used for Tables 9 and 10
that was outlined previously. Figure 4 demonstrates that
-------
60
50 -
40 -
30 -
20 -
10 -
0
Rate (%) S
0
-
0 *
• ° i * *
8 X
0 D
a £
DN^ "A*
1 [ *«T»S
o 8 *
© a $
£ ,
urvey Year
1984
*
1983
O
1982
a
1981
A
1979
O
1978
a
31 23456789 10 11
Vehicle Age (years)
Figure 4. Cumulative tampering prevalence as a
function of vehicle age for the
1978 - 1984 surveys.
I
OJ
-------
60
50 -
40 -
30 -
20 -
10 -
0
RatQ (%) S
•
-
•
-
.
_
A
0
• *
0 A 0 Q *
Q >l<
urvey Year
1984
*
1983
0
1982
D
1981
A
1979
O
1978
D
] 1 2 3 4 5 6 7 89 10 11
Vohiclg Ago (ygars)
Figure 5. Cumulative catalyst tampering rate as
a function of vehicle age for the
1978 - 1984 surveys.
i
co
-------
-38-
the relationship between tampering rate and vehicle age is
not only linear, but has remained nearly constant since the
first survey in 1978. The strong correlation is obvious
despite the different sizes, vehicle compositions, and
locations of the surveys. In Figure 5 the catalyst tampering
rate remains negligible for the first two to three years
of a vehicle's life, and then increases thereafter.
This delay in catalyst tampering is understandable, since
the catalytic converters on all new vehicles are warranted
for 5 years/50,000 miles by the manufacturer, providing an
incentive to maintain the catalysts on vehicles still
under warranty.
If the relationship between vehicle age and tampering
has not changed markedly, what accounts for the general
increase in overall tampering from earlier surveys? Figure
6 charts both the overall and catalyst tampering rate and
compares these to the proportion of surveyed vehicles five
years old or more in each survey. Figure 6 shows that the
proportion of older vehicles surveyed has increased steadily
from 27% in 1978 to 58% in the 1984 survey sample. Since
the 1981-1984 surveys covered 1975 and newer vehicles, each
successive survey reflects the increasing age of the
catalyst-equipped vehicle population. (The 1981 survey
covered vehicles up to seven years old, while the 1984
survey included vehicles up to ten years old.)
-------
Percent
60
50
40
30
20
10
5-Year Old or More
Vehicles Surveyed
o
Tampering Rate
Catalyst Tampering i
Rate
u>
VO
1978 1979 1980 1981 1982 1983 1984
Survey Year
Figure 6. Comparison of catalyst and overall
tampering rates with vehicle age as
a function of survey year.
-------
-40-
The increase in the proportion of older vehicles surveyed
coincides with increases in the overall and catalyst tampering
rate. Thus, the vehicles comprising the survey sample are
older in each successive survey, and as such are more
likely to have been tampered with, causing the overall
tampering rate to increase.
Manufacturer. Figure 7 presents the 1984 tampering rates
for each major manufacturer. Since the number of vehicles
surveyed for each individual foreign manufacturer is small,
foreign vehicles have been combined into two groups, European
and Japanese. As in previous surveys, the tampering rate
is higher among domestic than foreign manufacturers.
Figure 8 shows the trend in tampering rates for each
manufacturer over time. The American vehicles are at or
consistently above the overall tampering rate, while the
European and Japanese vehicles have a tampering incidence
consistently lower than the overall rate.
A number of factors might explain the discrepancy in
tampering rates among manufacturers. Differences in design
may make some vehicles more tamper-prone than others.
Changing market share history results in different age
distributions for vehicles of different makes, and vehicle
age is clearly related to tampering prevalence. Tampering
rates probably vary with geographic location and socioeconomic
-------
-41-
American Motors
General Motors
9%
TampQring RatQ (%)
Figure 7. Tampering rates by manufacturer
1984 survey.
-------
Tamponing Rato ("A
40
30 -
20 -
10 -
0
Manufacturor
Figure 8. TampQring prevalence by manufacturer
for the 1978 - 1984 surveys.
-------
-43-
background, so the owner demographics for different makes
may affect the likelihood of tampering. Finally, certain
types of vehicles (trucks,; for instance) are more likely
i
to be tampered, and thus manufacturers with production
concentrated in these types can be expected to have higher
tampering rates.
5. Effect of I/M Programs on Tampering
Inspection and maintenance (I/M) programs require
vehicles to meet specific idle emission standards. Vehicles
registered in these areas are required to be periodically
tested to assure that they comply with the specific idle
emission cutpoints established by these jurisdictions. In
addition to reducing emission levels by stimulating better
owner maintenance, I/M programs may deter some tampering
with emission control components. Data from previous surveys
has tended to support this proposition, since tampering in
I/M areas has been lower than in non-I/M areas.
Some I/M areas have also instituted antitampering
programs (ATPs), which involve periodic vehicle inspections
to check the integrity of specific emission control components.
Antitampering programs vary greatly in the components inspect-
ed and the vehicle model years covered, so that a vehicle which
would be inspected in one program area might not be inspected
in a different program area. Successful antitampering programs
-------
-44-
should directly deter tampering with the components and
model years covered by the program, and may have an indirect
deterrent effect on the rest of the vehicle population.
The 1984 survey encompassed six non-I/M areas, five
I/M-only areas, and three I/M + ATP areas. The proportion
of the survey sample covered under each program type was
discussed earlier (Table 5).
Table 11 compares the tampering rates in non-I/M,
I/M-only, and I/M + ATP areas. The tampering rates in
non-I/M areas were significantly higher than the rates in
I/M-only areas, which were in turn higher than the rates
in I/M + ATP areas. This is the same relationship found
in previous surveys, although the degree of program
effectiveness in 1984 exceeds that of earlier surveys.
Table 11 also shows that the tampering rate in non-I/M
areas has increased by over 50% since the first survey in
1978.
The component-specific tampering rates for cars and
trucks in each program area are presented in Table 12. The
tampering rates in non-I/M areas were greater than in I/M-only
areas for every component in both cars and trucks. Except
for the PCV system in trucks, the I/M-only rates exceeded
the I/M + ATP rates in every case as well. It should be
noted that certain I/M areas have weight limits that exclude
some light-duty trucks from their programs.
-------
-45-
TABLE 11
Tampering Prevalence in I/M and non-I/M Areas
Survey
Year
1978
1979
1981*
1982
1983
1984
non-I/M
19
20
14
19
29
31
Tampering
I/M-only
NS
13
NS
15
24
17
Rate ( % )
I/M + ATP
NS
NS
NS
10
16
11
Overall
19
18
14
17
26
22
NS = None Surveyed
*1981 survey was of limited scope, covering only two sites and
399 vehicles
-------
TABLE 12
Tanpering and Fuel Switdiing Prevalence by Vehicle Type in I/M and non-I/M Areas
non-I/M Areas
I/M-only Areas
I/M + ATP Areas
Overall
Tanpering
Category
At least one
component
tampered
Catalytic
Converter
Inlet Restrictor
Air Pump
System
Evaporative
Control System
PCV System
EGR System
Fuel Switched
cars(%)
31
9
14
11
4
3
15
19
trucks(%)
33
18
17
14
6
5
13
25
cars(%)
16
3
6
4
1
1
9
10
trucks (%)
25
11
9
11
3
1
13
16
cars(%)
11
3
5
2
1
1
3
8
trucks(%)
14
5
8
6
2
2
2
9
cars(%)
21
5
9
7
2
2
10
13
trucks(%)
27
14
14
12
5
3
10
19
0%
I
-------
-47-
The effect of I/M programs on catalyst tampering is
investigated more thoroughly in Table 13, where catalyst
tampering rates in each program area are presented for each
vehicle model year and vehicle type. The same trend in
program effectiveness is evident for cars and trucks of a
specific model year. The small sample sizes for some model
years and vehicle types, however, prevent some comparisons
from being made. For example, the truck rates by model
year in I/M-only and I/M + ATP areas are based on very small
sample sizes. These rates have been included in Table 13
for the sake of completeness and should not be considered
meaningful. Table 13 also shows the strong relationship
between vehicle age and catalyst tampering in cars and trucks,
particularly in non-I/M areas and in the overall database.
6. Effect of Antitampering Programs on Tampering
The impact of antitampering programs on tampering rates
is presented in Table 14, which compares the tampering rates
for components checked in the three I/M + ATP areas surveyed.
Boston, whose yearly inspection program covers filler neck
restrictors and catalysts on 1980 and later vehicles, had
very high tampering rates for these components on 1980 and
1981 model year vehicles. Boston's program had been in effect
over a year at the time of the survey. St. Louis had
significant tampering rates for a number of components on
1981 and 1982 model year vehicles. St. Louis' yearly
-------
TABLE 13
Catalytic Converter Tanpering Prevalence* by Vehicle Type in I/M and non-I/M Areas - 1984 Survey
non-I/M Areas
I/M only Areas
Automobiles
Model
Year
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
Number
Surveyed
77
150
167
222
111
158
145
147
138
130
Tampering
Rate(%)
23
16
21
11
10
8
6
1
1
0
Light-Duty Trucks
Number
Surveyed
5
13
16
16
42
50
43
55
66
56
Tanpering
Rate(%)
100
50
50
33
39
23
21
7
6
2
Automobiles
Number
Surveyed
70
114
129
155
132
135
139
111
115
108
Tanpering
Rate(%)
5
9
7
2
4
2
1
0
0
0
Light-Duty Trucks
Number
Surveyed
7
4
4
8
24
19
15
14
24
22
Tanpering
Rate(%)
20
0
i
0 co
43
17
0
21
7
8
0
* Many Light-Duty Trucks manufactured between 1975-79 were not originally equipped with catalysts,
and thus were excluded from this table.
-------
TABLE 13 (cont'd)
Catalytic Converter Tanpering Prevalence by Vehicle Type in I/M and non-I/M Areas - 1984 Survey
I/M + ATP Areas
Overall
Automobiles
Model
Year
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
Nunber
Surveyed
34
99
87
148
114
127
110
119
107
113
Tanpering
Rate(%)
10
1
8
7
1
3
3
0
0
0
Light-Duty Trucks
Nunber
Surveyed
4
5
5
10
14
27
6
20
21
33
Tanpering '
Rate(%)
0
0
0
0
29
4
0
5
0
0
Automobiles
Nunber
Surveyed
181
363
383
525
423
420
394
377
360
351
Tanpering
Rate(%)
14
10
13
7
6
4
4
1
1
0
Light-Duty Trucks
Nunber
Surveyed
16
22
25
34
80
96
64
89
111
111
Tanpering
Rate(%)
50
35
38
32
30
14
19
7
5
1
-------
-50-
TABLE 14
Tampering Rates (percent) for Cenponents Checked in I/M + ATP Areas - 1984 Survey
Component
Survey Site or System
Model Year
1980 1981 1982 1983 1984
Boston, MA Filler Neck
Restrictor
Catalyst
Filler Neck
or Catalyst
Portland, OR PCV System
Air System
EGR System
Catalyst
Filler Neck
Restrictor
Filler Neck
or Catalyst
Any of Above
St. Louis, MO PCV System
Air System
EGR System
Catalyst
Any of Above
11
7
15
0
0
1
1
0
1
2
*
*
*
*
*
7
2
10
0
0
0
0
0
0
0
0
3
0
5
7
3
0
3
1
0
0
0
0
0
1
3
5
4
3
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
*0omponent/model year not covered by antitampering program.
-------
-51-
program, however, had only been implemented seven months prior
to the survey. Portland's antitampering program appears to
be the most effective, with negligible tampering rates for all
components covered by the program.
7. Effectiveness of I/M-only vs. I/M + ATP
Figures 9(a) and (b) compare the effectiveness of I/M-only
programs and I/M + ATP in preventing tampering. Tampering
rates for Portland and New Jersey have been selected since
these sites represent long-standing I/M + ATP and I/M-only
programs, respectively. New Jersey instituted its I/M program
in February, 1974, and Portland's I/M + ATP program began in
July, 1975. Additionally, these are the only two 1984 survey
sites that had been surveyed in previous years. Figure 9(a)
shows that Portland's I/M + ATP has reduced overall tampering
and EGR tampering between 1982 and 1984 while AIR system and
catalyst tampering have remained very low. Over the same
period of time New Jersey's I/M-only program has had no
impact on overall tampering rates, and over the past five
years the tampering rates for catalyst, AIR, and EGR systems
have all increased markedly.
Half of the catalyst removals found in Portland in 1984
were from out-of-state vehicles not previously subjected to
the local inspection program. In contrast, all of the vehicles
with missing catalysts in New Jersey were in-state vehicles
-------
-52-
Tampering Rata (2)
20
18
16
14
12
10
8
6
4
2
0
102
22
oz
12
102
Overall Catalyst AIR System
a) Portland. OR
[ |
1984
EGR System
Tampering Rata (2)
20
18
16
14
12
10
8
6
4
2
0
162 162
112
52
32
02
32
12 12
Overall Catalyst AIR System EGR System
b) Now Jersey
Figures 9(a) and (b). Comparison of data from
1984 survey sites that had been
surveyed previously.
1979
1982
1984
-------
-53-
subject to the state's I/M program. The difference in EGR
tampering rates for the two sites in also noteworthy because
EGR reduces NOX emissions, a pollutant not checked by idle
emissions testing. These results suggest that I/M-only
programs are not as effective as I/M + ATP in reducing
tampering rates, and that many tampered vehicles are appar-
ently able to pass an idle emissions test undetected.
8. I/M Programs and Geographic Bias
Determining the impact of I/M and I/M + ATP programs on
tampering and misfueling may be complicated by a possible
geographic bias in the survey data. The 1984 survey sites
are listed below by program type.
Non-I/M ' I/M-Only I/M + ATP
Bakersfield, CA Reno, NV Boston, MA
Dallas, TX Washington, DC St. Louis, MO
Birmingham, AL New Jersey Portland, OR
Cincinnati, OH New York, NY
Tampa, PL Milwaukee, WI
El Paso, TX
It is apparent that the geographic regions of the U.S.
are not equally represented in each program type. The northern
states are disproportionately represented in the I/M areas,
while only one northern non-I/M site (Cincinnati) was surveyed.
Similarly, no southern I/M sites were surveyed, while four
southern non-I/M sites (Dallas, Birmingham, Tampa, and El
Paso) were included. Also four of the northern survey areas
(Boston, New York City, New Jersey, and Washington) are
concentrated within 500 miles of each other.
-------
-54-
The southern states appear to have higher tampering
rates than the northern states, which would increase the
discrepancy between the I/M and non-I/M tampering rates as
surveyed. In comparing the data from non-I/M sites in
Table 7, the component-specific tampering rates in Cincinnati
are lower than in the four southern cities surveyed for every
component except the PCV and EGR systems. Cincinnati also
has a much lower misfueling rate (Table 2). The possibility
of a geographic influence cannot be further investigated
readily using the 1984 survey data, but it may influence
site selection in future surveys.
9. Correlation between Tampering and Idle Emissions
As was mentioned previously, vehicles which are subject
to an I/M program must meet specific idle emissions cutpoints.
To assess the relationship between tampering and fuel switch-
ing and idle failure rates, the idle emissions from vehicles
have been tested against the cutpoints established by the
I/M program where they were sampled. Vehicles in non-I/M
areas were tested against the cutpoints specified by the New
Jersey I/M program. The cutpoints for each I/M area are
listed in Appendix C.
The results of the idle tests are presented in Figure 10
for vehicles in the various tampering and fuel switching
categories. Only 10% of the survey vehicles free of tampering
and fuel switching failed an idle test, while 60% of the
-------
FigurQ 10
Distribution of SurvQy Sample Among Tampering*.
Fuel Switching, and Idle Test Categories
EntirQ survGy
sample
, 100%
Okay
46%
Arguably
tampgred
29%
Tamponed
22%
U1
01
I
*excludes malfunctioning vehicles (4% of total)
-------
-56-
tampered and fuel switched vehicles failed that test. These
results indicate that a substantially larger proportion of
tampered and fuel switched vehicles than of okay vehicles
fail an idle test at typical I/M cutpoints. This is partly
due to the tendency for tampered vehicles to have misadjusted
carburetors, as is shown in Figure 11. This Venn diagram
shows that 71% of the tampered vehicles with conventional
carburetors also had missing sealed plugs or limiter caps.
It must be noted from Figure 10, however, that 40% of these
tampered and misfueled vehicles were still able to pass the
idle test.
Table 15 shows the percentage of vehicles that failed
the idle emissions test for each vehicle condition. Over one-
third of the tampered vehicles failed the idle emissions test
for either HC or CO, while only 7% of the okay vehicles
exceeded limits for HC or CO. Over one-third of the vehicles
that either had been fuel switched or had their catalysts
removed also exceeded HC and CO limits. Conversely, nearly
two-thirds of the vehicles with inoperative or missing
catalysts were still able to pass an idle emissions test.
Interestingly, a significant number of arguably tampered
vehicles also produced excess idle emissions. Since the
majority of arguable tampering involves idle speed limiter
caps, the high failure rate demonstrates the adverse idle
emissions impact of improperly adjusted carburetors.
-------
-57-
Carbureted Vehicles
have been tampered
(924 total)
that
Carbureted Vehicles
with Arguably
Tampered Carburetors
(1729 total)
Figure 11. Overlap of Tampering and carburetor misadjustment among conventionally
carbureted vehicles - 1984 Survey.
-------
-58-
TABLE 15
Idle Test Failure Rates (percent) by Pollutant
and Vehicle Condition
Vehicle Condition
Pollutant Okay
HC 7
CO 7
Arguably
Tampered Tampered
38 23
36 26
Cat. Removed/
Misfueled
40
35
TABLE 16
Mean Idle Emissions by Vehicle Condition
Survey HC emissions(ppm) CO emissions(%)
Sites Tampered Okay Tampered Okay
non-I/M 430.0 65.6 3.0 0.4
I/M only 287.2 60.1 2.4 0.4
I/M + ATP 323.4 60.4 2.1 0.3
OVERALL 381.7 62.3 2.7 0.4
-------
-59-
The mean idle emissions for tampered and okay vehicles
are presented in Table 16 by program type. The mean idle
emissions from tampered vehicles were considerably higher
than from okay vehicles. Overall HC emissions were 513%
higher, while overall CO emissions were 575% higher. The
means for non-I/M areas were higher than for I/M-only and
I/M + ATP areas.
To investigate the impact of I/M programs on idle
emissions, the emissions from okay and tampered vehicles in
each program type can be compared. The data indicates that
idle HC emissions from okay vehicles in I/M areas were only
8% lower than from vehicles in non-I/M areas, and that the
idle CO emissions were not affected by I/M programs. Anti-
tampering programs had no additional impact on idle HC and
CO emissions of okay vehicles (Table 16). These findings
agree with Table 15, which shows that nearly all okay vehicles
would pass the idle emissions test. Idle HC and CO emissions
from tampered vehicles, however, were 33% and 20% lower,
respectively, in I/M-only area than in non-I/M areas, suggest-
ing that idle emissions may be reduced from vehicles for
which tampering is not successfully deterred. It should be
noted that a vehicle's idle emissions are only loosely related
to its emissions under normal driving conditions.
-------
-60-
B. FUEL SWITCHING
1. Fuel Switching Indicators and Overlap
Fuel switching is more easily defined than measured,
since no single indicator can accurately determine its
prevalence. Since 1981 the surveys have used a combination
of three indicators to measure fuel switching more accurately:
a tampered fuel filler inlet restrictor, a positive Plumbtesmo.
test for lead deposits in the tailpipe, and a gasoline lead
concentration of more than 0.05 grams per gallon (gpg). Of
these three indicators, only a tampered inlet restrictor is
also considered tampering, and as such is used to calculate
both tampering and fuel switching rates. Since false positive
indications should be extremely rare for these measures, the
percentage of vehicles with at least one positive indicator
is a reasonable minimum estimate of fuel switching.
The presence of any of these three indicators suggests
that a given vehicle has been misfueled; their absence, how-
ever, does not rule it out. For example, fuel samples could
only be obtained from 70% of the unleaded vehicles surveyed,
limiting the scope of this variable. A vehicle misfueled
repeatedly with leaded gasoline may also have little detect-
able lead in its fuel tank due to subsequent proper fueling.
Similarly, a vehicle with an untampered fuel filler inlet
restrictor may have been fueled at a leaded pump equipped
with a smaller nozzle, or by using a funnel or similar device.
-------
-61-
The tailpipe lead test, due to the difficulties of field
administration, may also fail to identify misfueling, and
older vehicles may have had their tailpipes replaced since
last operated on leaded fuel. The uncertainty in these
measures, then, is always toward underestimating the number
of vehicles misfueled.
The limitations of the fuel switching indicators can be
seen in their incomplete overlap. The results from these
indicators would be expected to overlap significantly, since
they are three indicators of the same phenomenon. This has
not held true, however, in the 1984 survey or in previous
surveys. The Venn diagram (Figure 12) illustrates the degree
of overlap in the 1984 results. For example, only 73% of
the vehicles having leaded fuel in their tank also registered
a positive Plumbtesmo test. Additionally, only 35% of the
vehicles with tampered inlet restrictors actually had leaded
gasoline in their tanks at the time of the survey. The
incomplete overlap reflects the limitations of each indicator
as well as the different aspects of fuel switching each
indicator identifies.
2. Fuel Switching Rates
Of the vehicles requiring unleaded fuel, 14% were
identified as misfueled by at least one of the indicators
discussed above. The fuel switching incidence by survey site
and program type is listed in Table 17. Since fuel samples
-------
-62-
Positive Plumbtesmo
(354 Total)
Leaded Fuel in Tank
(235 Total)
Figure 12.
Tampered Inlet
Restrictor
(401 Total)
Overlap of fuel switching indicators among unleaded vehicles -
1984 Survey.
-------
-63-
TABLE 17
Fuel Switching Rates among Unleaded Vehicles by Site
and Indicator - 1984 Survey
Leaded Tampered
Positive
>1 Positive
Survey Fuel in Inlet Plumbtesmo
Location Tank(%) Restrictor (% ) (%)
Bakersfield, CA
Dallas, TX
Birmingham, AL
Cincinnati, OH
Tampa, FL
El Paso, TX
Reno , NV
Washington, DC
New Jersey
New York, NY
Milwaukee, WI
Boston, MA
St. Louis, MO
Portland, OR
ALL NON-I/M SITES
ALL I/M ONLY SITES
ALL I/M+ATP SITES
ALL SITES
3
11
17
7
15
13
17
2
2
14
1
4
7
2
11
5
4
7
Non-I/M Areas
11
12
19
8
17
17
I/M Only Areas
15
9
5
2
5
I/M -I- ATP Areas
5
7
4
14
6
6
10
8
15
21
7
16
16
17
2
6
5
3
2
6
4
14
5
4
8
Indicators
(%)
14
18
25
12
23
23
22
10
8
13
7
9
10
7
19
10
8
14
-------
-64-
could not be obtained from all unleaded vehicles surveyed,
the incidence of leaded fuel in the tank may be higher than
the overall misfueling rate for some survey sites (e.g., New
York). Non-I/M sites had the highest fuel switching rate
(19%), followed by I/M-only and I/M + ATP areas. The preva-
lence of each fuel switching indicator in non-I/M areas was
at least twice that found in I/M-only areas.
Tables 18 and 19 compare the fuel switching rates from
the 1984 survey with previous surveys. Table 18 shows that
although the overall fuel switching rate has not changed
appreciably, the rate for non-I/M areas has been increasing
steadily. Table 19 shows that inlet restrictor tampering
has increased steadily, while the prevalence of the ojther
two fuel switching indicators has remained unchanged.
Table 20 presents the combined tampering and fuel
switching rates for the 1984 survey. The percentage of
vehicles that were tampered or fuel switched was 24%, only
2% higher than the tampering rate alone. . The overlap in the
fuel switching and tampering rates results mainly from the
inlet restrictor tampering rates being used to calculate
both values.
-------
-65-
TABLE 18
Fuel Switching Prevalence among Unleaded Vehicles
in I/M and non-I/M Areas
Survey
Year
1978
1979
1981**
1982
1983
1984
non-I/M
4*
12*
16
15
17
19
Fuel Switching
I/M only I/M
NS
3*
NS
7
12
10
Rate (%)
+ ATP
NS
NS
NS
2*
5
8
Overall
4*
9*
16
11
14
14
*Plumbtesmo test not used.
**1981 survey was of limited scope, covering only two sites and
399 vehicles.
NS: None surveyed
TABLE 19
Fuel Switching Rates among Unleaded Vehicles
by Indicator and Survey Year
Survey Leaded Fuel Tampered Inlet Positive ^1 Positive
Year in Tank(%) Restrictor(%) Plumbtesmo(%) Indicators(%)
1978
1979
1981
1982
1983
1984
4
10
7
6
7
8
3
4
6
6
7
10
*
*
8
7
10
9
4
9
16
11
14
14
* No Plumbtesmo test
-------
-66-
"i,
i
TABLE 20
Combined Tampering and Fuel Switching Rates - 1984 Survey
Catalyst-equipped vehicles Unleaded vehicles
Survey
Location
Bakersfield, CA
Dallas, TX
Birmingham, AL
Cincinnati , OH
Tampa , FL
El Paso, TX
Reno , NV
Washington, DC
New Jersey
New York, NY
Milwaukee, WI
Boston, MA
St. Louis, MO
Portland, OR
ALL NON-I/M SITES
ALL I/M-ONLY SITES
ALL I/M + ATP SITES
with catalysts removed or
fuel switched (%)
t
Non-I/M Areas
19
22
28
16
26
27
I/M-only Areas
25
13
9
16
8
I/M + ATP Areas
9
12
7
23
12
9
either tampered o
fuel switched (%)
34
31
35
31
42
34
35
25
18
25
12
17
17
10
34
20
13
ALL SITES
16
24
-------
-67-
3. Fuel Switching by Vehicle Type
As was reported previously, the fuel switching rates for
trucks was considerably higher than for passenger cars - 19%
vs. 13% (Table 1). The filler neck restrictor tampering
rates were also higher for trucks than for passenger cars
(Table 1).
4. Fuel Switching and Vehicle Age
Table 21 correlates vehicle age and model year with fuel
switching rates for the 1978-1984 surveys. This method of
analysis is identical to the one used earlier to compare
tampering rates across model years and vehicle ages. Analyzing
Table 21 diagonally shows that the rate of fuel switching
"increased with vehicle age .in every survey taken. The fuel
switching rate reached a maximum of 20-30% when the vehicles
were six or seven years old. A similar though less pronounced
pattern can be seen when the data is analyzed within model
years (horizontally) or within vehicle age groups (vertically).
5. Catalyst Tampering and Fuel Switching
Consumers and mechanics remove catalytic converters for
a number of reasons, but much of their motivation is related
to fuel switching. The vehicle owner may remove the catalytic
converter either prior to misfueling, or after some misfueling
if the vehicle's driveability has been adversely affected by a
catalyst damaged from the repeated misfueling. The data from
-------
TABLE 21
Percentage of Fuel Switching (and Sanple Size) among Unleaded Vehicles by Model Year and Vehicle Age
at Time of Survey
Model
Year
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
First
3(462)
5(182)
5(250)
9(57)
6(328)
2(296)
Second
4(471)
6(226)
7(444)
11(62)
8(451)
3(438)
Third
6(465)
9(205)
8(447)
16(55)
9(428)
6(388)
Year of Vehicle Life
Fourth Fifth Sixth Seventh Eighth Ninth Tenth
8(457)
8(210) 11(487)
12(432) 19(269) 18(455)
18(74) 12(377) ' 15(221) 24(486)
18(60) 13(283) 23(176) 27(357)
15(316) 37(49) 14(249) 21(147) 24(314)
6(255) 14(213) 30(20) 17(146) 24(82) 26(174)
00
I
-------
-69-
this survey cannot be used to distinguish between these two
situations, but can be used to examine the extent to which
these;types of abuse occur in conjunction.
|
Of the catalyst-equipped vehicles surveyed, 16% were
either catalyst tampered or fuel switched (Table 20). The
rates in non-I/M, I/M-only, and I/M + ATP areas were 23%,
12%, and 9%, respectively.
Figure 13 depicts the degree of overlap between catalyst
removal and fuel switching. Vehicles with catalyst tampering
exclusive of fuel switching were relatively uncommon — only
one-third of the catalyst tampered vehicles were not fuel
switched. Fuel switching, however, is not always accompanied
by catalyst removal. Over two-thirds of the.fuel switched
vehicles still have their catalysts.
6. Gasoline Lead Concentrations
Of the vehicles identified by any of the three indicators
as misfueled, 37% had only trace amounts of lead (less than
0.05 gpg) in their gasoline when inspected. These vehicles,
then, were identified as fuel switched by a tampered filler
restrictor and/or a positive Plumbtesmo test. Figure 14
presents the distribution of lead concentrations of 0.05 gpg
or more in misfueled vehicles. This figure shows that 39% of
the misfueled vehicles have a gasoline lead concentration
in excess of 1.0 gpg. Since the average lead concentration
-------
-70-
Catalyst Tampering
(273 Total)
Fuel Switching
(566 Total)
Figure 13. Overlap of catalyst tampering and fuel switching among
catalyst-equipped vehicles - 1984 Survey.
-------
-71-
PercQntagQ of Misfuelod Vehicles
45
40
35
30
25
20
15
10
0
GasolinQ Load Concentration (grams/gallon)
Figure 14. Lead concentrations in fuel sampled
from misfueled vehicles.
-------
-72-
in leaded gasoline at the refinery is 1.1 gpg, the results
suggest that about 39% of the misfueled vehicles are habitually
misfueled, as the leaded gasoline in their tanks showed no
evidence of having been diluted by subsequent tankfuls of
unleaded gas.
-------
-73-
APPENDIX A
RELEVANT PORTIONS OF THE CLEAN AIR ACT
Section 203(a)(3): The following acts and the causing thereof
are prohibited —
(A) for any person to remove or render inoperative any device
or element of design installed on or in a motor vehicle or
motor vehicle engine in compliance with regulations under this
title prior to its sale and delivery to the ultimate purchaser,
or for any manufacturer or dealer knowingly to remove or
render inoperative any such device or element of design after
such sale and delivery to the ultimate purchaser; or
(B) for any person engaged in the business of repairing,
servicing, selling, leasing, or trading motor vehicles or
motor vehicle engines, or who operates a fleet of motor
vehicles, knowingly to remove or render inoperative any
device or element of design installed on or.in a motor
vehicle or motor vehicle engine in compliance with regulations
under this title following its sale and delivery to the
ultimate purchaser.
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-74-
APPENDIX B
SURVEY AND DATA RECORDING PROCEDURES
1. Explanation of Survey Forms
The forms on the following pages were used for recording
the survey data in the field. The forms were forced choice to
ensure coding consistency, and were designed to facilitate
direct data entry. The following codes were used to record
data for the major system components on the data sheets:
0 - Not originally equipped
1 - Functioning properly
2 - Electrical disconnect
3 - Vacuum disconnect
4 - Mechanical disconnect
5 - Incorrectly routed hose
6 - Non-stock equipment
7 - Missing item
8 - Misadjusted item
9 - Malfunctioning
P - Stock equipment
A - Add on equipment
Additional codes were used for those components which
could not be classified into the above categories. A brief
description of each data entry follows.
-------
SURVEY - FORM A (Rear)
12
ID NUMBER
MAKE
MODEL
"IT
VEHICLE TYPE (1-Car, 2-Truck)
14 15
• LICENSE PLATE (State)
HC, PPM
CO, %
29
31T
32
34
TANK CAP (1, 7, 9)
TANK LABEL (0, 1, 7)
FUEL INLET RESTRICTOR (0, 1, 4, 7)
CAT (0, 1, 7, 9)
EXHAUST SYSTEM (P-stock, N-non)
EXHAUST INTEGRITY (1, 9)
FUEL SAMPLE (Y, N)
Ol
I
24
PLUMBTESMO (Positive, Negative)
2$ 27
ODOMETER READING, Thousand
28
3/84
DASH LABEL (0, 1, 7)
0 - Not Original Equipped
1 - Functioning Properly
2 - Electrical Disconnect
3 - Vacuum Disconnect
4 - Mechanical Disconnect
5 - Incorrectly Routed Hose
6 - Non-Stock
7 - Missing Item
8 - Misadjusted Item
9 - Malfunctioning
-------
NATIONAL SURVEY - FORM B (Underhood)
ID NUMBER
EGR VALVE (0, 1, 3. 7, 9)
EGR SENSOI (0, 1, 3, 5, 7, 9) (CTO-Transducers-Other)
MODEL W.yi
r
I* | DISPLACEMENT (CID or liters)
TT
13 23
ENGINE
VIN*
35"
77
n
~
Tl
CAT EQUIPPED (1-Yes; 2-Ho; 3-Can't Tell)
AIR CLEANER (P-Stock; 6-Non)
HEATED AIR INTAKE (0, 1, 3, 4, 6, 7,,9)
PCV (0. 1, 3, 4, 6, 7)
TURBO (0, P-Stock, 6-Non, A-Add on)
•If Engine Family Not Found
3/84
50
0 - Not Original Equipped
1 - Functioning Properly
2 - Electrical Disconnect
3 - Vacuum Disconnect
4 - Mechanical Disconnect
5 - Incorrectly Routed Hose
6 - Non-Stock
7 - Hissing Item
8 - Mlsadjusted Item
9 - Malfunctioning
P - Stock
EVAP. (0, 1, 3, 4, 5, 7, 9)
AIR PUMP (0, 1, 4, 7, 9)
AIR PUMP BELT (0, 1, 7, 8)
P.A.I.R. (0, 1, 4, 7, 9)
INTAKE MANIFOLD (P, 6)
EXHAUST MANIFOLD (P, 6)
SENSOR (0, 1, 2. 4, 7)
DISTRIBUTOR (P. 6
VACUUM SPARK RETARD (0, 1, 2, 3)
CARBURETOR TYPE (P, Sealed, Fuel Injection, 6)
CARBURETOR, NUMBER OF BARRELS (0, 1, 2, 4)
IDLE STOP SOl.rilOIl) 10. 1, 2, 7, 9)
LIMITER CAP (0, 1, 4, 7, 8-Sealed Plugs Removed)
-------
-77-
Form A - Rear
1-4 ID Number - Vehicles are numbered sequentially as
they are inspected. This number is preceded by a
site identifying letter.
5-8 Make
9-12 Model
13 Vehicle Type - coded as follows: 1 = car, 2 = truck
14-15 License Plate - State abbreviation
16-19 Exhaust gas HC concentration (in ppm) at curb idle.
20-23 Exhaust gas CO concentration (in percent) at curb idle,
24 Plumbtesmo - Plumbtesmo paper is used to check for the
presence of lead in vehicle exhaust pipes. A positive
indication is coded as 'P1 and a negative as 'N'.
25-27 Odometer - mileage in thousands
28 Dash Label - displays the fuel required and is coded
'0', 'I1, or '7'.
29 Tank Cap - seals the fuel tank during normal operating
conditions and is coded '!', '7', or '9'.
30 Tank Label - displays required fuel and is coded '0',
'I1, or '7'.
-------
-78-
31 Filler Neck Inlet Restrictor (unleaded vehicles only) -
The restrictor is designed to prevent the introduction
of leaded fuel into a vehicle requiring unleaded fuel.
It is coded '0', 'I1, '4' (widened), or '7'.
32 Catalytic Converter - oxidizes the HC and CO to water
and CC-2 in the exhaust gas. Later model catalysts
also reduce oxides of nitrogen. The converter is
coded '0', '!', '7' (entire catalyst canister removed),
or '9' (high temperature discoloration, usually light
blue).
33 Exhaust System - if originally equipped a 'P' is coded.
If non-stock an "N1 is coded.
34 Exhaust System Integrity - the condition of the exhaust
system is coded '!' (no obvious leaks) or '9' (leaks
evident).
35 Fuel Sample - indicates if inspector was able to take
fuel sample for later lead analysis ('Y1 or 'N')-
Form B - Format
1-4 ID Number - same as on Form A
Exhaust Gas Recirculation (EGR) System - directs a
portion of the exhaust gases back into the cylinders
to reduce NOX emissions in the exhaust gas. The
-------
-79-
standard EGR configuration consists of a vacuum line
from the carburetor to a sensor (used to detect
engine operating temperature to activate the EGR
valve), and another vacuum line from the sensor to
the EGR valve.
5 EGR Control valve - coded '0', 'I1, '3', '7', or
'9' .
6 EGR Sensor - coded '0', '1', '3', ' 5' , '7', or
'91 .
7-8 Vehicle Model year
9-12 Displacement - as recorded on the underhood emission
label.
13-23 Engine Family - as recorded on the underhood emission
label.
24-36 Non-serial number portion of VIN - as recorded on the
driver's side of the dash under the windshield or the
driver's door post. The VIN is recorded only if the
engine family can not be determined.
37 Originally Catalyst Equipped - as recorded on the
underhood emission label or the driver's door post.
38 Air Cleaner - is coded 'P' (stock) or '6'.
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39 Heated Air Intake - provides warm air to the carburetor
during cold engine operation. The heated air intake
is coded '0', 'I1, '3', '4', '6' (custom air cleaner),
'7' (stovepipe hose), or '9' (vacuum override).
40 Positive Crankcase Ventilation (PCV) system - prevents
crankcase emissions by purging the crankcase of blow-
by gases which leak between the piston rings and the
cylinder wall in the combustion chamber under high
pressures. The PCV system is coded '0', '!', '3',
'4' (fresh air hose), '6' (includes fuel economy
devices), or '7' .
41 Turbocharger - coded '0', '61, 'P', or 'A'.
42 Evaporative Control System (ECS) - controls vapors
from the fuel tank and carburetor. Some systems have
two lines: from the fuel tank to the canister, and
from the canister to the carburetor or air cleaner
(for purging the canister). Other systems have a
third line connected to the carburetor. The ECS is
coded '0', '!', '3' (carburetor line), '4' (tank
line), '5', '7', or '9' (air cleaner unsealed).
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Air Injection System - extends the combustion process
into the engine's exhaust system by injecting fresh
air into the exhaust ports, lowering exhaust emissions
while still maintaining proper vehicle performance.
Two types of air injection systems are currently used.
One type uses a belt-driven air pump to direct air
through a control valve and into the exhaust manifold.
The other type is a Pulse Air Injection Reaction
(PAIR) system, which uses an aspirator located in the
air cleaner to supply air to the exhaust manifold.
43 Air Pump System - for the purposes of this report,
consists of the air pump and control valve and is
coded '0' (if a PAIR or none), '!', '4' (excluding
belt removal), '?', or '9'.
44 Air Pump Belt - is coded '0' (if PAIR), 'I1, '7', or
'8' (loose belt).
45 PAIR - coded '0' (if air pump system or none), 'I1,
'4', '?', or '9'.
46 Intake Manifold - coded 'P' or '6'.
47 Exhaust Manifold - coded 'P1 or '6'.
48 Oxygen Sensor - Controls the air-fuel mixture going
into the engine of vehicles equipped with three-way
catalytic converters. The sensor is coded '0', '!',
'2', '4' (unscrewed), or '7'.
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49 Distributor - coded 'P1 or '6'.
50 Vacuum Spark Retard - retards the spark during idle
to delay ignition within the combustion chamber and
increase exhaust temperature, prolonging the com-
bustion process and reducing HC emissions. Vacuum
spark retard is coded 'O1, 'I1, '2', or '3'.
51 Idle Stop Solenoid - provides an idle stop for
maintaining idle speeds at higher rpm levels and
prevents the throttle plate from fully closing during
deceleration to minimize CO emissions. The idle stop
solenoid is coded '0', 'I1, '2', '71, or '91.
53 Limiter Caps - plastic caps on the idle mixture screws
to limit carburetor adjustments. The limiter caps
are coded 'O1, '!', '4' (tabs broken or bent), '7',
or '8' (sealed plugs removed).
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2. Classification Of Component Conditions
The table below was used to classify the various system
components as 'tampered', "arguably tampered', or 'malfunctioning'
Only those codes which are applicable to a given component
are listed. Codes for 'not originally equipped'. and 'functioning
properly1 are not included in this table. Refer to Appendix B,
Part 1 for an explanation of the codes.
Component/system
Dash Label
Tank Cap
Tank Label
Filler Neck Restrictor
Catalytic Converter
Oxygen Sensor
PCV System
Idle Stop Solenoid
Heated Air Intake
Evaporative Control
System
Aspirated Air
Injection System
Air Pump Belt
Codes from form
| 2 3 | 4
or T
T T
T T
T
T A
T T
5 | 6 7 | 9
A
A
A
T
T M
T
T T
T M
T A M
T T M
M
T = tampered
A - arguably tampered
M = malfunctioning
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Codes from form
Component/system | 2 I 3 I 4 | 5 I
Air
EGR
EGR
Pump System T
Control Valve T
Sensor T T
T M
T M
T
Vacuum Spark Retard T T
T = tampered
A - arguably tampered
M = malfunctioning
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3. Fuel Sample Collection and Labeling Procedures
A fuel sample was taken from each vehicle requiring
unleaded fuel. These samples were collected in four-ounce
bottles with a hand-operated fuel pump. Once the sample was
drawn, the fuel was replaced with an equivalent amount of
unleaded fuel if the driver requested, and the pump was flushed
with unleaded fuel.
Each bottle was identified with an adhesive label that
had the vehicle identifying survey number on it. The vehicle
identifying number was the first entry on the data forms
described in Part 1 of Appendix B.
Prior to shipment from the field, a sample tag with the
same identifying number was attached to each bottle. The
bottles were packed, labeled, and shipped to NEIC Chemistry
Branch according to the shipper's requirements and the NEIC
Policy and Procedures Manual.
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4. Plumbtesmo Application
1) Clean a portion of the inside of the tailpipe large enough
for the test paper by wiping it out with a paper towel or
cloth. This may be necessary to remove soot deposits
which might mask the color change.
2) Moisten the Plumbtesmo paper with distilled water and
immediately* press firmly against the surface to be tested
for approximately thirty seconds. If the tailpipe is hot
you may wish to clamp the test paper in the tailpipe
using a clean clamp.
*Note; The Plumbtesmo paper must be applied during the
time that the paper is yellow for the reaction to take
place. After approximately 15 seconds the yellow color
disappears and the paper is no longer effective. Excess
water also interferes with the reaction.
Care must be taken to avoid contamination of the test paper,
If a person has recently handled a test paper with a
positive reaction, some lead or reactive chemical may
have been transferred to their fingers. Subsequently
handling a clean test paper may cause contamination.
3) After removing the test paper, determine whether a color
change has occurred. Red or pink coloration indicates
the presence of lead.
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5. Field Quality Control/Assurance
Reference and calibration gases were used to ensure the
accuracy of the emissions analyzer. Horiba gases certified by
RTF were used as reference gases. Two cylinders of reference
gas were used to validate the accuracy of the calibration gases
before they were taken to the field on each survey.
Three calibration gases (Horiba) were used. These gases
were a mixture of CO and HC in nitrogen and were used to check
the instrument at least three times daily. These calibration
gases were certified by the manufacturer and the RTF reference
gases. Their approximate compositions were:
8% CO
1560 ppm HC (Hexane equivalent)
4% CO
827 ppm HC (Hexane equivalent)
1.6% CO
320 ppm HC (Hexane equivalent)
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APPENDIX C
EMISSION OUTPOINTS FOR I/M AREAS
The table below lists the emission outpoints used by the I/M
areas covered in the 1984 tampering survey. The outpoints for
pre-1975 vehicles are not included, since these vehicles were
not surveyed.
Survey Site
Boston, MA
Milwaukee, WI
New Jersey
New York, NY
Model Year
Emissions Cutpoints
CO (%) HC (ppm)
1975-79
1980
1981+
1975-77
1978-79
1980
1981+
1975-80
1981 +
1975-77
1978
1979
1980
1981+
1975+
1975+
1975-79
1980
1981+
1975-79
1980+
4.0
2.7
1.2
6.0
4.0
2.5
1.2
3.0
1.2
5.7
4.3
3.0
2.7
1.2
0.5*
3.0
6.0
3.0
1.2
6.5
1.5
400
300
220
600
400
275
220
300
220
700
500
400
330
220
175*
-
600
300
220
600
300
Portland, OR
Reno, NV
St. Louis, MO
Washington, DC
*Cutpoints for Portland are established by make and model
year. The listed cutpoints are applicable to most 1975
and newer vehicles.
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