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Office of Air and Radiation
Motor Vehicle Tampering Survey -1988
May 1989
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Field Operations and Support Division
Office of Mobile Sources
Washington, D.C.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
JUN 16 060
OFFICE OF
AIR AND RADIATION
MEMORANDUM
SUBJECT: 1988 Motor Vehicle Tampering Survey Report
FROM: Al Manna to, Chief
Regional/State/Local lS<55r5frfa16ron Section
TO: Regional Librarians
Two copies of the Field Operations and Support Division 1988
Tampering Survey are attached for inclusion in your library's
periodical section. A limited .supply of these reports are
available, so please retain these as permanent copies and direct
any specific inquiries to your Region's Air Management division,
or have them write to:
U.S. EPA
Office of Air and Radiation (EN-397F)
Regional/State/Local Coordination Section
401 M Street S.W.
Washington, DC 20460
Verbal inquiries can be directed to Paul Argyropoulos at 202-
475-8839 for those areas within Regions I, III, V and IX; to
Bonnie Crystall at 202-475-8837 for those areas within Regions II,
IV, VII, and VIII; and to Dean Ross at 202-382-2947 for those areas
within Regions VI and X.
Attachment
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TABLE OF CONTENTS
EXECUTIVE SUMMARY 1
Introduction 1
Conclusions 2
BACKGROUND 6
SURVEY METHODS 7
Site Descriptions 8
RESULTS 13
Vehicle Tampering 13
Site and Aggregate Totals 13
Types of Tampering 13
Vehicle Characteristics and Tampering 16
Manufacturer 16
Vehicle Type 17
Vehicle Age 19
Impact of I/M and Antitampering Programs 21
Tampering Trends for Selected Sites 23
Correlation Between Tampering and Idle Emissions 31
Fuel Switching 34
Fuel Switching Indicators and Overlap 34
Fuel Switching Trends 36
Fuel Switching by Vehicle Type 38
Fuel Switching and Catalyst Tampering 39
Gasoline Lead Concentrations 41
APPENDIXES
A. Relevant Portions of Clean Air Act 43
B. Survey and Data Recording Procedures 43
C. Emission Cutpoints for I/M Areas 49
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LIST OF FIGURES
1. Tampering rates for selected components by program type 4
2. (a) Overall tampering by vehicle age for vehicles not covered
by l/M and/or antitampering programs 5
(b) Comparison of catalyst tampering by vehicle age between
vehicles covered and not covered by a catalyst inspection program 5
3. Breakdown of surveyed vehicles by condition and extent of tampering
(Percentages do not add up to 100% because of rounding error) 14
4. Tampering rates by manufacturer: 1988 survey 18
5. Classification of 1988 survey sites by program type (and model year
coverage), with the resulting tampering and fuel switching rates for
each program type 22
6. (a)-(f) Comparisons of component-specific tampering rates by model
year between vehicles covered and not covered by ATPs 27 - 29
(a) Catalytic Converter 27
(b) Inlet Restrictor . 27
(c) Air Pump System 28
(d) Evaporative System 28
(e) PCV System 29
(f) EGR System 29
7. Comparison of overall component-specific tampering rates among
vehicles covered and not covered by ATPs (summary of Figures 6(a)-(f)) 30
8. Distribution of unleaded vehicles surveyed among tampering, misfueling,
and idle test categories 32
9. (a) Overlap of fuel switching indicators among misfueled vehicles
for which Jill three indicators were inspected 35
(b) Breakdown of misfueled vehicles in 9(a) by prevalence of each
indicator combination 35
10. Overlap of catalyst tampering and fuel switching among catalyst-equipped
vehicles -1988 survey 39
11. (a) Overlap of indicators used by ATPs to detect missing/damaged catalysts.
Only includes vehicles for which all three indicators were inspected and are
not covered by an ATP with plumbtesmo testing 40
(b) Breakdown of vehicles in 11(a) by prevalence of each indicator combination 40
12. Distribution of lead concentrations in leaded fuel sampled from fuel switched
vehicles: 1984 - 88. Percentages based on all fuel switched vehicles, including
those using unleaded fuel ( < 0.05 gpg.) 42
- ii -
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LIST OF TABLES
1. 1988 Tampering Survey Summary : 15
2. Prevalence of Tampering by Component 16
3. Component-Specific Tampering Rates (P ercent)
by Survey Location -1988 Survey 17
4. Tampering Percentage (and Sample Size) by Model Year
and Vehicle Age at Time of Survey 20
5. Percentage of Catalyst Removal (and Sample Size) among
Catalyst-Equipped Vehicles by Model Year and Vehicle Age
at Time of Survey. 20
6. Comparison of 1988 Survey Sample to Actual Nationwide
Vehicle Fleet 23
7. Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in ATP-only Areas
Surveyed between 1983 -1988 24
8. Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in I/M + ATP Areas
Surveyed between 1983 -1988 25
9. Idle Test Failure Rates (Percent) by Pollutant and
Vehicle Condition 33
10. Mean Idle Emissions for Tampered and Okay Vehicles
Within Each Program Type 33
11. Fuel Switching Rates among Unleaded Vehicles by Site
and Indicator: 1988 Survey 36
12. Combined Tampering and Fuel Switching Rates -1988 Survey 37
13. Prevalence of Fuel Switching Indicators by Program Type 38
14. Prevalence of Fuel Switching Indicators by Vehicle Type 38
- iii -
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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 15 cities
between March and August, 1988. The areas surveyed and the number of vehicles
inspected per site are listed below.
TUcson, AZ
424
San Antonio, TX
533
Phoenix, AZ
450
Columbia, SC
505
Stockton, CA
500
New York, NY
406
Baton Rouge, LA
523
New Jersey
520
Houston, TX
550
Birmingham, AT-
500
El Paso, TX
515
Orlando, FL
500
Albuquerque, NM
500
Medford, OR
328
Oklahoma City, OK
505
TOTAL 7,259 vehicles
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:
a. The effect of vehicle inspection and maintenance (I/M) programs and
antitampering programs (ATPs) on tampering and fuel switching.
b. The relationship between tampering and vehicle idle emissions.
c. The distribution of tampering by vehicle age, type, manufacturer, and
other variables of interest.
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 categories 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 (i.e., may have
resulted from either tampering or malmaintenance)
3. Malfunctioning
4. Okay - all control devices present and apparently operating properly
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Motor Vehicle Tampering Survey -1988
Page 2
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.
The site selection in recent tampering surveys has been based more on the need
to evaluate control program effectiveness than the desire to methodically sample the
U.S. vehicle population. In the 1988 survey, for example, only the 1975 -1983 model year
vehicles surveyed in New York were covered by an I/M-only program. These vehicles
comprised only 2% of the survey, compared to the 10% of the vehicles nationwide which
are subject to such programs. The lack of any true I/M-only sites in the 1988 survey
makes it inappropriate to use this survey as representative of the nationwide vehicle
population. Rather, the 1988 survey sample is an appropriate tool for evaluating tamper-
ing prevalence at any particular site, and for evaluating control program effectiveness
where "before" and "after" data exist. This report will refrain from comparing the overall
1988 survey results with prior surveys because of the overrepresentation of control
programs in the survey sample.
CONCLUSIONS
Tampering among vehicles not covered by I/M and/or anti- tampering programs
was 23%, compared to 17% and 16% for those vehicles covered by ATP-only and I/M
+ ATP, respectively. Such comparisons between program categories should be made
carefully, since some of the control programs cover only newer model years of vehicles,
which historically have lower tampering rates than the older vehicles not covered by the
control programs.
Because of the large variation in program types and coverages, the vehicles are
classified based on the program restrictions within each site. In Oklahoma City, for
example, only the 1979 and newer vehicles are covered by the area's antitampering
program; the 1975 -1978 vehicles are thus classified as "non-I/M".
The survey results reveal a disparity in how effectively control programs reduce
certain kinds of tampering. Antitampering programs with catalyst and inlet restrictor
inspections have generally been very effective in reducing tampering with these com-
ponents. When antitampering programs include inspections of various underhood
components, however, tampering with these components has in general declined only
slightly or not at all. Overall, underhood components had higher tampering rates than
that found for the catalytic converter, with the air pump being the single most tampered
component (11% of equipped vehicles). These trends will be investigated more
thoroughly later in this report.
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Motor Vehicle Tampering Survey -1988
Page 3
Fuel-Related Tampering
The prevalence of vehicles with missing or damaged catalytic converters within
each program type is depicted in Figure 1. A vehicle can be considered to have a missing
or inoperative catalyst if the converter has been removed, the inlet restrictor is tampered,
or the plumbtesmo test is positive. (These three criteria are used by many antitampering
programs.) A missing or damaged converter can increase HC and CO emissions by an
average of 475% and 425%, respectively.1 For vehicles equipped with three-way con-
verters, substantial increases in NOx emissions would also be expected. In addition,
converter tampering on trucks was found to be greater than on automobiles (7% vs. 4%).
Fuel switching, defined as the presence of any of three specific indicators , was
found in 10% of the unleaded vehicles not covered by I/M and/or ATPs in the 1988 survey.
Fuel switching among vehicles in ATP-only and I/M + ATP areas was 5% and 4%,
respectively. The pattern of overlap among the three misfueling 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.
Catalyst Tampering and Vehicle Aee
The probability that a vehicle has been tampered with is clearly related to its age,
as has been shown in previous surveys. This is evident in Figure 2(a), which depicts
overall tampering as a function of vehicle age for those vehicles not covered by I/M and/or
antitampering programs. Figure 2(b) compares the impact of vehicle age on catalyst
tampering among vehicles covered and not covered by converter inspection programs.
Overall, converter tampering is much lower on vehicles covered by converter inspection
programs than on vehicles not covered by such programs (1% vs. 7%), and the effective-
ness of inspection programs is particularly noticeable among the oldest vehicles surveyed
(vehicles that are most likely to be tampered with).
1 The emissions increases mentioned in this report are from a study of three-way catalyst vehicles presented in
Anti-Tampcring and Anti-Mlsfuellng Programs to Reduce In-Ust 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, or a gasoline lead concentration of more than O.QS gram per gallon.
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Motor Vehicle Tampering Survey -1988
Page 4
Component
Catalytic Converter 2%
™ 1%
Inlet Restrictor
Positive Plumbtesmo
0%
Tampering (%)
non — l/M
ATP — only
l/M + ATP
Figure 1. Tampering rates for selected components by program type.
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Motor Vehicle Tampering Survey -1988 Page 5
Vehicle Age (years)
(a)
Catalyst Tampering (%)
30
Vehicles Not
Covered
Vehicles
Covered
--O--
6 7 8 9 10
Vehicle Age (years)
(b)
Figure 2(a). Overall tampering by vehicle age for vehicles not
covered by I/M and/or antitampering programs.
2(b). Comparison of catalyst tampering by vehicle age
between vehicles covered and not covered by
a catalyst inspection program.
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Motor Vehicle Tampering Survey -1988
Page 6
BACKGROUND
EPA estimates that motor vehicle emissions nationwide account for 58% of the
total carbon monoxide (CO), 38% of the airborne lead, 27% of the hydrocarbons (HC),
and 34% of the oxides of nitrogen (NOx) emitted into the atmosphere.3 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. The first pollution control devices
were installed on vehicles in 1962, and most light- duty vehicles manufactured since 1968
have been equipped with a variety of emission control devices to meet required emissions
standards.
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 introduc-
tion 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.
Before 1978, the EPA had data suggesting that tampering with emission control
devices and misfueling of "unleaded only" vehicles with leaded gasoline were 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 annual surveys have been conducted
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.
The uses for the tampering surveys have evolved since the first survey was con-
ducted in 1978. Since 1983, the tampering survey results for some locations have been
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 (MOBILE4) to estimate both the emissions
loading impact and the reductions that may be achieved by various control programs.
Comparing survey results before and after implementation of a control program is an
excellent method for evaluating program effectiveness. Sites for the surveys are chosen
in light of the need for data on specific areas either currently operating or considering
programs, as well as the continuing need to monitor the types and extent of tampering
and fuel switching nationwide.
3 National Air Pollutant Emission Estimates, 1940-1986, EPA-450/4-87-024, January, 1988.
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Motor Vehicle Tampering Survey -1988
Page 7
SURVEY METHODS
The 1988 tampering survey was conducted for FOSD by the National Center for
Vehicle Emissions Control and Safety at Colorado State University (CSU). Ap-
proximately 400 to 600 vehicles were inspected in each of 15 cities between March and
August, 1988, and the entire survey includes 7,259 vehicles. The mix of vehicles inspected
was assumed to be a self-weighting sample, and no attempt was made to force the sample
into matching the national vehicle mix.
Each inspection team consisted of at least four members: three CSU personnel,
one or two EPA representatives, and frequently a State or local agency representative.
The CSU personnel, assisted by the State or local person, performed the actual inspec-
tions, while the EPA representative(s) monitored 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® 4 test paper; and
6. Integrity of fuel inlet restrictor checked.
Three changes have been made in the survey methodology for 1988. The two
separate variables for the oxygen sensor and the rest of the computer system have been
consolidated into a single variable representing the entire computer system. Similarly,
the two variables for the EGR system (the control valve and sensor) have been combined
into a single EGR system variable. Finally, the 1988 survey is the Erst survey in which
gasoline samples were taken from both leaded and unleaded vehicles. The results from
the leaded vehicles will be discussed separately in this report, and were not used to
calculate any fuel switching rates among the unleaded vehicles. The inspections and
recording procedures are fully detailed in Appendix B.
The survey data base has been reviewed by CSU and EPA to ensure its accuracy,
and has been offered to the major automotive manufacturers to review the classification
and reporting of their respective vehicles.
The tampering 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, or if the emission control label indicates an unleaded fuel requirement
(Le., catalyst-equipped). A vehicle's designation as "unleaded" or "leaded" may be
changed upon subsequent review of the data. Fuel switching rates are thus based only
on the population of unleaded vehicles surveyed. Similarly, tampering rates for specific
components are based only on the vehicles originally equipped with the component.
4 Plumbtesmo* is a registered trademark, and appears hereafter without the"®". It is manufactured by
Macheiy-Nagel, Durcn, W. Germany, and marketed by Gallard-Schlesinger Chemical Corp., Carle Place, New
York.
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Motor Vehicle Tampering Survey -1988
Page 8
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, since individuals who have tampered with or misfueled their
vehicles are less likely to allow their vehicles to be surveyed. The overall refusal rate was
very low (3%), however, and only two survey sites had refusal rates over 5%. A brief
description of each survey site follows. Unless otherwise noted, the survey locations
within a given city were changed daily.
SITE DESCRIPTIONS
Tbscon, AZ
I/M + ATP
Dates: March 14 -18,1988
Vehicles Surveyed: 424
Fuel Samples: 355
Refusal Rate: 0%
Phoenix, AZ
I/M + ATP
Dates: March 21 - 25,1988
Vehicles Surveyed: 450
Fuel Samples: 388
Refusal Rate: 0%
The Ibcson and Phoenix surveys were conducted at each city's centralized inspec-
tion stations. Three different stations were used in Tbcson, while five different stations
were used in Phoenix. The antitampering programs in Phoenix and Tucson include a
Plumbtesmo test and inspection of the catalytic converter, air injection system, and inlet
restrictor on all 1975 and newer vehicles.
Stockton, CA
Non-I/M
Dates: March 28 - April 1,1988
Vehicles Surveyed: 500
Fuel Samples: 388
Refusal Rate: 1%
Roadside pullovers were conducted with the assistance of the California Highway
Patrol. While Stockton was a non-I/M area at the time of the survey, a decentralized
biennial I/M + ATP was instituted on April 1,1988.
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Motor Vehicle Tampering Survey -1988
Page 9
Baton Rouge, LA
ATP-only
Dates: April 11-15,1988
Vehicles Surveyed: 523
Fuel Samples: 447
Refusal Rate: 8%
Roadside pullovers were conducted with the assistance of the Louisiana State
Police. Survey locations were the same as in the 1985 and 1986 surveys. The decentral-
ized antitampering program in Baton Rouge includes a Plumbtesmo test and inspection
of all emission control devices on 1980 and newer vehicles.
Houston, TX
ATP-only
Dates: April 18 - 22,1988
Vehicles Surveyed: 550
Fuel Samples: 393
Refusal Rate: 2%
El Paso, TX
I/M + ATP
Dates: May 2-6,1988
Vehicles Surveyed: 515
Fuel Samples: 356
Refusal Rate: 1%
San Antonio, TX
Non-I/M
Dates: May 23 - 27,1988
Vehicles Surveyed: 533
Fuel Samples: 421
Refusal Rate: 5%
Roadside pullovers in El Paso, Houston, and San Antonio were conducted with
the assistance of the Texas Department of Public Safety. The decentralized antitamper-
ing program in Houston and El Paso includes Plumbtesmo testing and inspection of the
catalytic converter and inlet restrictor on 1980 and newer vehicles, and inspection of the
PCV, evaporative, air pump, and EGR systems on 1968 and later vehicles. El Paso also
has an I/M program for checking tailpipe CO emissions.
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Motor Vehicle Tampering Survey -1988 Page 10
Albuquerque, NM
Non-I/M
Dates: May 9 - 13,1988
Vehicles Surveyed: 500
Fuel Samples: 355
Refusal Rate: 2%
The Albuquerque survey was conducted with the assistance of the New Mexico
State Police. Albuquerque was a non-I/M area at the time of the survey, but implemented
anl/M + ATP in September 1988. Albuquerque also had an I/M program from January,
1983 to March, 1984.
Oklahoma City, OK
ATP-only
Dates: May 16 - 20,1988
Vehicles Surveyed: 505
Fuel Samples: 423
Refusal Rate: 5%
The Oklahoma City survey was conducted in Oklahoma City (two days), Edmond,
Norman, and Midwest City. The Oklahoma Highway Patrol and the local law enforce-
ment offices in these municipalities assisted with the roadside pullovers. Oklahoma City's
decentralized antitampering program includes a check of all emission control com-
ponents and Plumbtesmo testing on 1979 and newer vehicles.
Columbia, SC
Non-I/M
Dates: June 6 -10,1988
Vehicles Surveyed: 505
Fuel Samples: 368
Refusal Rate: 2%
Officers from the Columbia Police Department assisted with the roadside
pullovers.
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Motor Vehicle Tampering Survey -1988
Page 11
New York, NY
I/M + ATP
Dates: July 11-15,1988
Vehicles Surveyed: 406
Fuel Samples: 332
Refusal Rate: 13%
Roadside pullovers were conducted in Manhattan with the assistance of the New
York Police Department. New York's decentralized I/M + ATP includes an annual
inspection of all emission control components on 1984 and newer vehicles. The high
refusal rate for this highly urban site was not unexpected.
New Jersey
I/M + ATP
Dates: July 18 - 22,1988
Vehicles Surveyed: 520
Fuel Samples: 387
Refusal Rate: 1%
Roadside pullovers were conducted in Trenton, Bordentown, Freehold, and
Eatontown with the assistance of local law enforcement officers in these municipalities.
The survey was also conducted one day at the state inspection station in Hightstown.
New Jersey's statewide centralized I/M + ATP includes an annual catalyst inspection
of 1975 and newer vehicles.
Birmingham, AL
Non-I/M
Dates: July 25 - 28,1988
Vehicles Surveyed: 500
Fuel Samples: 397
Refusal Rate: 3%
Roadside pullovers were conducted with the help of the Alabama State Police and
the Homewood City Police. Inspection locations included Birmingham (three days) and
Homewood.
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Motor Vehicle Tampering Survey -1988
Page 12
Orlando, FL
Non-I/M
Dates: August 1-5,1988
Vehicles Surveyed: 500
Fuel Samples: 373
Refusal Rate: 3%
Roadside pullovers were conducted in Orlando (four days) and Edgewood with
the assistance of the Florida Highway Patrol.
Medford, OR
I/M + ATP
Dates: August 23 - 26,1988
Vehicles Surveyed: 328
Fuel Samples: 218
Refusal Rate: 0%
The Medford survey was conducted at the state-run inspection station in Medford
for four days. Medford's antitampering program includes biennial inspection of all
emission control devices on 1975 and later vehicles.
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Motor Vehicle Tampering Survey -1988
Page 13
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.5 The criteria used for component clas-
sification are presented in Appendix B. This overall tampering rate is useful only as a
rough indicator of the emissions impact of a tampering problem, since the different
components making up the rate may have widely varying emissions implications.
The proportion of inspected vehicles with at least one tampered component was
19%. One-third of the surveyed vehicles 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. Forty-six percent of the tampered vehicles had
multiple components tampered, and 13% had four or more instances of tampering.
Ibble 1 summarizes the 1988 survey data by site. As in previous surveys, the overall
tampering in 1988 varied considerably from site to site. This can be attributed to the
variety of program configurations among the cities surveyed and to geographic differen-
ces.
Ihble 1 also contains the refusal rate at each survey site. The overall refusal rate
for the survey was very low (3%), and only two survey sites had refusal rates exceeding
5%.
2. Types offampering
The tampering rates for all emission control components and systems surveyed in
1988 are presented in Ihble 2. The component-specific tampering rates for the 1988
survey are presented by survey site in Tkble 3. Only those vehicles originally equipped
with a particular component are considered when computing the tampering rate for that
component. The site-specific tampering rates listed in Ibbles 1 and 3 are for all vehicles
surveyed at each location, including out-of-state vehicles and other vehicles possibly not
covered by any local inspection program. The tampering rates for only vehicles covered
by local control programs will be examined later in this report.
5 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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Motor Vehicle Tampering Survey -1988
Page 14
Condition of Number of Tampered
Surveyed Vehicles Components
Figure 3.
Breakdown of surveyed vehicles by condition and
extent of tampering. (Percentages do not add
up to 100& because of rounding error.)
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Motor Vehicle Tampering Survey -1988
Page 15
Table 1
1988 Tampering Survey Summary
Number of Tampering Misfueling Survey Refusal
Survey Location Vehicles Rate (%) Rate (%) Type* Rate (%)
Tuscon, AZ
424
21
5
C
0
Phoenix, AZ
450
22
5
C
0
Stockton, CA
500
21
11
R
1
Baton Rouge, LA
523
21
7
R
8
Houston, TX
550
17
4
R
2
El Paso, TX
515
20
6
R
1
Albuquerque, NM
500
20
6
R
2
Oklahoma City, OK
505
20
10
R
5
San Antonio, TX
533
26
10
R
5
Columbia, SC
505
20
8
R
2
New York, NY
406
15
2
R
13
New Jersey
520
9
1
R, C
1
Birmingham, AL
500
18
6
R
3
Orlando, FL
500
21
8
R
3
Medford, OR
328
12
5
C
0
OVERALL
7,259
19
6
-
3
*R = roadside pullovers, C = centralized inspection stations
Ibble 2 shows that air pump system tampering remains the single most common
type (11% of equipped vehicles). Tampering with PCV and evaporative systems also
show no evidence of subsiding. Also of interest is the slight but measurable tampering
found with the oxygen sensor and computer control system. Because of the difficulty in
inspecting the oxygen sensors (no determination could be made on 86 vehicles), tamper-
ing with this component could be as high as 3% if all of the uninspected oxygen sensors
were tampered with. Oxygen sensor tampering is of considerable interest because of the
dramatic emissions increases which result from its disablement -- an average increase of
445% for HC and 1,242% for CO.6 As the vehicle fleet equipped with oxygen sensors
and computers ages, tampering with these relatively new devices may increase.
6
Antltamnf ring and Antl.\fkfi»-lin? Programs fa Rerfm-e fn.fke Fmi-reinns from Motor Vehicles.
EPA-AA-TTS-83-10, December 31,1983.
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Motor Vehicle Tampering Survey -1988
Page 16
Table 2
Prevalence of Tampering by Component
Component/System
Tampering Rate (%)
Catalytic Converter
5
Filler Neck Restrictor
6
Air Pump System
11
Air Pump Belt
8
Air Pump/Valve
7
Aspirator*
2
PCV System
6
Evaporative Control System
6
EGR System
7
Heated Air Intake
3
Oxygen Sensor and
Computer System
1
* Vehicles with aspirated air systems are not equipped with other listed air-
injection components, nor do conventional systems include aspirators.
Tbble 3 shows the wide variation in tampering from site to site for any given
component. Air pump system tampering for example, ranged from 3% in New Jersey
to 18% in Orlando. This range is partly due to the effectiveness of I/M and antitampering
programs (as will be discussed later in this report), geographic location, and
socioeconomic background.
3. Vehicle Characteristics and Tampering
The next section of this report investigates the inter-relationship between tamper-
ing and three vehicle characteristics: manufacturer, vehicle type (car or truck), and age.
Manufacturer. Figure 4 presents the 1988 tampering rates for each major
manufacturer. The smaller foreign manufacturers have been combined into two groups,
Other European and Other Asian. Vehicle tampering was higher among vehicles of
domestic manufacture than among those of foreign manufacture. Overall, tampering
with domestically manufactured vehicles was more then twice that found for the foreign
manufactured vehicles (23% vs. 9%).
A number of factors might explain the difference in tampering prevalence 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 seem to vary with geographic location and socioeconomic background, so the
owner demographics for different makes may affect the likelihood of tampering.
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Motor Vehicle Tampering Survey -1988
Page 17
Table 3
Component-Specific Tampering Rates (%) by Survey Location
1988 Survey
Survey
Catalytic
Inlet
Air Pump
PCY
EGR
Evaporative
Any
Location
Converter
Restrictor
System
System
System
System
Component
Tucson, AZ
1
3
6
9
9
5
21
Phoenix, AZ
2
5
13
9
10
8
22
Stockton, CA
3
10
10
5
7
5
21
Baton Rouge, LA
7
6
11
8
8
6
21
Houston, TX
4
4
10
5
8
6
17
El Paso, TX
5
5
11
6
7
10
20
Albuquerque, NM
5
6
14
4
10
7
20
Oklahoma City, OK
7
9
8
5
6
6
20
San Antonio, TX
8
10
13
7
8
7
26
Columbia, SC
6
8
12
6
8
7
20
New York, NY
3
2
8
6
5
5
15
New Jersey
1
1
3
3
3
2
9
Birmingham, AL
7
6
16
5
7
5
18
Orlando, FL
8
9
18
6
7
6
21
Medford, OR
0
3
4
2
7
2
12
OVERALL
5
6
11
6
7
6
19
Vehicle Type. The overall tampering prevalence for light-duty trucks (LDTs) was
21%, compared to 19% for automobiles (LDVs). Since the 1986 tampering survey, the
tampering rates for cars and trucks have basically been the same, and the discrepancy
between car and truck tampering decreased steadily in surveys prior to 1986. While the
overall tampering rate is less meaningful than the rates for individual components, even
the component-specific truck rates tend to converge upon the usually lower automobile
rates. As was mentioned earlier, the most critical components (e.g., catalytic converters)
are still tampered with more frequently on trucks.
Many factors may be contributing to the convergence in car and truck tampering.
Since most of the vehicles surveyed in 1988 were subject to control programs, the relative
car and truck tampering rates may reflect increased emphasis on truck tampering
detection by the inspection programs. Also, the proportion of imported trucks within
the total truck population surveyed has increased from 15% to 26% between 1982 and
1988, with many of the smaller trucks being utilized as cars. Since imported vehicles are
tampered with much less frequently than domestic vehicles, the increase in imported
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Motor Vehicle Tampering Survey -1988
Page 18
Ford
General Motors
Volkswagen
Chrysler/AMC
Other European
Other Asian
Toyota
Mazda
' Nissan
Honda
23%
25%
Tampering (%)
Figure 4. Tampering by Manufacturer: 1988 Survey.
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Motor Vehicle Tampering Survey -1988
Page 19
trucks within the truck population surveyed may be contributing to the lower truck
tampering prevalence.
Vehicle. Age.. Tbble 4 relates vehicle age and model year with tampering
prevalence for the 1978-1988 surveys. Catalytic converter removal rates are similarly
related to vehicle age and model year in Ihble 5. The results from any given survey are
entered diagonally in each table.
The results in Tables 4 and 5 indicate that vehicle tampering increases directly with
vehicle age. Examining Tbble 4 diagonally (by survey) shows that tampering increases
consistently with vehicle age in each survey conducted. In the 1988 survey, for example,
the tampering rate increases from 1% for first year (1988) vehicles to 62% among the
1975 model year vehicles surveyed.
Ihble 5 shows a similar, though less pronounced, increase in catalyst removal. The
catalyst tampering rate remains negligible for the first five years of a vehicle's life, and
then increases thereafter. This delay in catalyst tampering is understandable, since the
emission control components 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. A similar delay in overall tampering is abbreviated in Thble 4, but
becomes more evident when only non-I/M vehicles are examined (Figure 2 (a)). Examin-
ing 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), geography, or program coverage on tampering.
1\vo additional ways of analyzing Tables 4 and 5 address the impact of model year
on tampering rates. Analyzing these Tables horizontally (holding the model year con-
stant) 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.) Interestingly, overall tampering with post-1980 model year vehicles
appears to be less than that for pre-1981 model year vehicles when both groups of vehicles
were new (less than five years old), but the tampering rates for these groups converge
with increasing vehicle age. In Tbble 4, for example, overall tampering with 1981 and
1979 model year vehicles during their first year of use was 2% and 6%, respectively. By
their eighth year of use, however, the tampering rates for the 1981 and 1979 model year
vehicles were nearly the same — 34% and 36%, respectively.
Tables 4 and 5 can also be examined vertically (holding vehicle age constant),
which provides a look at the tampering rates for different model year vehicles of the same
age. This approach permits a crude examination of trends in tampering adjusted for
vehicle age. Examining Ihble 4 vertically, for example, shows a decrease in overall
tampering from the 1978 survey to the 1988 survey for vehicles in each of their first five
years of use. This decrease in overall tampering appears to lessen in the later years of a
vehicle's life. A similar vertical analysis of Ibble 5 does not show any clear pattern or
trend in age-specific catalyst tampering.
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Motor Vehicle Tampering Survey -1988 Page 20
Thble4
Tampering Percentage (and Sample Size) by Model Year and Vehicle Age at Time of Survey
Year of Vehicle Life
Model
Year 1st M 3ri 4th 5th 6th 7lh 8th 9th 10th 11th 12th 13th 14th
1988 1(524)
1987 1(627) 1(832)
1986 1(757) 2(1058) 3(915)
1985 2(816) 3(1130) 3(972) 6(855)
1984 1(462) 2(1001) 5(1018) 7(908) 8(765)
1983 7(182) 4(471) 6(710) 7(706) 10(633) 15(532)
1982 1(250) 4(226) 7(466) 9(621) 11(574) 19(525) 21(506)
1981 2(57) 7(448) 13(206) 15(458) 11(607) 19(560) 26(501) 34(479)
1980 5(63) 9(454) 15(211) 18(516) 25(564) 25(556) 28(472) 32(419)
1979 6(371) 9(59) 18(477) 31(288) 28(503) 37(673) 36(699) 42(555) 44(464)
1978 7(298) 14(502) 15(79) 21(430) 39(238) 34(559) 37(562) 50(548) 49(443) 55(404)
1977 10(457) 15(476) 21(66) 26(316) 44(190) 41(408) 48(452) 48(465) 49(356) 54(265)
1976 18(395) 19(374) 29(52) 26(317) 40(171) 39(385) 49(369) 53(318) 60(219) 61(179)
1975 22(274) 22(271) 32(22) 37(183) 55(89) 46(197) 54(194) 60(198) 65(103) 62(113)
1974 33(276) 27(242)
1973 32(253) 36(251)
Table 5
Percentage of Catalyst RemovaI(and Sample Size) among Catalyst-equipped Vehicles
by Model Year and Vehicle Age at Time of Survey
Year of Vehicle Life
Model
Year
1st
2nd
3rd
4th
5th
6th
7th 8th 9th 10th 11th 12th 13th 14th
1988
0(521)
1987
0(627)
0(810)
1986
0(757)
0(1058) 0(887)
1985
0(808)
1(1128) 0(972)
1(818)
1984
0(462)
0(978)
1(1018) 1(908)
1(726)
1983
1(179)
2(471)
0(686)
1(706)
1(633)
2(505)
1982
0(250)
1(225)
2(465)
2(597)
1(574)
3(525)
3(466)
1981
0(57)
2(441)
5(204)
6(457)
3(567)
5(552)
7(499) 9(421)
1980
2(61)
2(428)
3(200)
6(487)
6(522)
7(528) 8(440) 9(346)
1979
0(326)
4(55)
6(429)
12(252) 10(455) 12(572) 12(638) 13(505) 13(376)
1978
0(291)
0(445)
0(71)
4(362)
8(213)
8(486) 10(472) 10(466) 15(394) 13(312)
1977
1(417)
1(417)
2(59)
2(271)
11(166) 14(357) 17(379) 19(409) 11(320) 19(212)
1976
2(377)
2(305)
10(48)
6(257) 12(139) 12(314) 15(291) 20(276) 19(184) 15(137)
1975
2(242)
2(204)
26(19) 12(139) 23(75) 16(174) 21(130) 23(167) 25(77) 14(72)
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Motor Vehicle Tampering Survey -1988
Page 21
The comparisons made in the two preceding paragraphs involve observations
made in different survey locations during different years, and are affected by the site
selection in each survey. An increasing percentage of the 1981 and newer vehicles in
recent surveys have been covered by antitampering programs, which could contribute to
the lower tampering found among newer vehicles. The impact of improved technology
on tampering can be more accurately assessed by examining only vehicles from non-I/M
areas (Figure2(a». The data in Figure 2(a) suggest that tampering with new technology
vehicles that are no longer covered by new car or emissions warranties (i.e., post-1981
vehicles that are six to eight years old) is consistent with tampering among older
technology vehicles (pre-1981 — over eight years old).
4. Impact of I/M and Antitampering Programs
Inspection and maintenance (I/M) programs require vehicles to meet specific idle
emission standards. Vehicles registered in areas with these programs 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 historically been lower than in non-I/M areas.
Many local 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 inspected and the
vehicle model years covered, so that a vehicle or component which would be inspected
in one program area might not be inspected in a different program area. Successful
antitampering programs should reduce existing tampering and deter future tampering
with the components and model years covered by the program.
Classifying the survey areas into program types is made difficult by the consider-
able variation in control programs. For example, New York City's antitampering program
includes inspection of all emission control devices, but only on 1984 and newer vehicles
(1983 and older vehicles are covered by an I/M-only program). New Jersey's antitamper-
ing program covers 1975 and newer vehicles, but only includes inspection of the catalyst.
In order to minimize the impact of these variations in program types and model
year coverages, the vehicles in the 1988 survey can be classified by the model year
restrictions applicable in the program areas surveyed. These classifications, and the
resulting tampering and fuel switching rates for each program type, are shown in Figure
5. Since New York's antitampering program only covers 1984 and newer vehicles, for
example, only those model year vehicles are classified as "I/M + ATP"; the 1975-1983
vehicles surveyed in New York are classified as "I/M-only". This method of classification
does not take into consideration the components inspected by each program, a
, program's effectiveness, or the frequency of inspection. Any comparisons between
program types (e.g., I/M + ATP vs. non-I/M) should thus be made carefully.
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Motor Vehicle Tampering Survey -1988
Page 22
Nori—l/M
Albuquerque, NM
Birmingham, AL
Columbia, SC
Orlando, FL
San Antonio, TX
Stockton, CA
Baton Rouge, LA (1975-1979)
Oklahoma City, OK (1975—1978)
ATP —only
Baton Rouge, LA (1980+)
Houston, TX
Oklahoma City, OK (1979+)
l/M + ATP
El Paso, TX
Medford, OR
New Jersey
New York, NY (1984 + )
Phoenix, AZ
Tucson, AZ
l/M —only
New York, NY
1975-1983)
Note: Program covers all model years surveyed unless otherwise indicated.
Program Type
- ¦ 1 — I
30% 20% 10% 0% 0% 5% 10% 15%
Tampering (%) Fuel Switching (%)
*the l/M—only rates have been excluded because they are not representative
of l/M—only areas nationwide
Figure 5 Classification of 1988 survey sites by program type
(and model year coverage), with the resulting
tampering and fuel switching rates for each
program type.
I
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Motor Vehicle Tampering Survey -1988
Page 23
Table 6
Comparison of 1988 Survey Sample
to Actual Nationwide Vehicle Fleet
Program Type
non-I/M
I/M-only
I/M + ATP
ATP-only
Percentage within
Survey Sample (%)
Approximate Percentage
of Nationwide Fleet (%)*
43
2
34
21
58
12
20
10
•From County Population Estimates: July 1.1987 and 1986. U.S.
Department of Commerce - Bureau of the Census, September, 1988.
Another factor affecting comparisons in Figure 5 is the overrepresentation in the
survey sample of areas with some kind of control program. This is a deliberate feature
of the survey's design, as was discussed earlier, and focuses attention on evaluating the
effectiveness of specific individual programs, liable 6 compares the proportion of the
1988 survey sample and the national vehicle fleet under control programs. Because of
the need to evaluate control program effectiveness, the survey overrepresents the portion
of the national vehicle fleet under control programs. Vehicles covered by an I/M + ATP
or an ATP-only comprised 55% of the survey sample, while only approximately 30% of
the national vehicle fleet were under such programs. Of even greater significance
regarding survey representation, the surveyed vehicles covered by an I/M-only program
consist only of the 1983 and older vehicles in New York City, comprising only 2% of the
survey sample. The I/M-only rates have thus been excluded from Figure 5 since they are
not representative of I/M-only areas nationwide.
The impact of I/M and antitampering programs in specific locations can be
examined by comparing the 1988 survey data with that from earlier surveys. Com-
parisons made between surveys widely spaced in time, however, must take into con-
sideration the differences in average vehicle age in each survey. The average odometer
reading per vehicle surveyed in 1988, for example, is over 20% greater than it was in 1983.
Since vehicle mileage correlates with vehicle age, which is directly related to tampering
prevalence, a significant increase in tampering might be expected to have occurred
between 1983 and 1988, even if all other factors remained constant (car/truck distribu-
tion, owner demographics, etc.). Inferences regarding program effects should thus be
made with this in mind.
Ibbles 7 and 8 present tampering data for the three ATP-only and six I/M + ATP
sites surveyed, respectively. Because of the large number of programs represented in
Ibbles 7 and 8, only a few representative comparisons will be discussed in this report.
Detailed analysis of each program's effectiveness is beyond the scope of this report. The
comparisons made in these Tables have been limited to the specific components and
vehicle model years covered by each antitampering program actually in operation during
the 1988 survey. In some instances this reduces the sample size substantially. The
tampering data listed in Ibbles 7 and 8 were compiled only for surveyed vehicles included
S. Tampering TVends for Selected Sites
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Motor Vehicle Tampering Survey -1988
Page 24
Table 7
Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs
in ATP-only Areas
Surveyed between 1983 -
1988
Tampering Prevalence (%) by Survey
Year
Survey Location
Component and
(Program Start Date)
Model Year Covered
1983
1984 1985
1986
1987
.1988
Baton Rouge, LA
Catalyst
80 +
.
4
3
1
(1/86)
Inlet Restrictor
80 +
-
3
1
-
2
Pos. Plumbtesmo
80 +
-
5
2
-
0
PCV System
80 +
-
2
3
-
6
Evap. System
80 +
-
3
3
-
3
Air Pump System
80 +
-
6
4
-
7
EGR System
80 +
4
4
5
Houston, TX
Catalyst
80 +
6
1
3
1
1
(7/84)
Inlet Restrictor
80 +
1
0
2
1
0
Pos. Plumbtesmo
80 +
8
2
2
1
1
PCV System
75 +
9
4
7
7
6
Evap. System
75 +
8
4
7
8
5
Air Pump System
75 +
9
6
8
6
10
EGR System
75 +
19
9
9
8
7
Oklahoma City, OK
Catalyst
79 +
3
(1/87)
Inlet Restrictor
79 +
-
-
-
-
4
Pos. Plumbtesmo
79 +
-
-
-
-
2
PCV System
79 +
-
-
-
-
3
Evap. System
79 +
-
-
-
-
4
Air Pump System
79 +
-
-
-
-
6
EGR System
79 +
4
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Motor Vehicle Tampering Survey -1988
Page 25
Table 8
Tampering Prevalence among Vehicles and Components
Covered by Antitampering Programs in I/M + ATP Areas
Surveyed between 1983 -
1988
Tampering Prevalence (%) by Survey
Year
Survey Location
Component and
(Program Start Date)
Model Year Covered
1983
1984
1985
1986
1987
1988
El Paso, TX
Catalyst
80 +
-
3
-
-
2
2
(1/86)
Inlet Restrictor
80 +
-
3
-
-
1
2
Pos. Plumbtesmo
80 +
-
6
-
-
1
1
PCV System
75 +
-
7
-
-
8
5
-
Evap. System
75 +
-
5
-
-
7
10
Air Pump System
75 +
-
17
-
-
9
12
EGR System
75 +
-
11
-
-
9
5
New Jersey, varied locations
Catalyst
75 +
-
5
-
5
4
1
(I/M-2/74, ATP-12/85)
Medford, OR
Catalyst
75 +
-
-
-
-
-
0
(1/86)
Inlet Restrictor
75 +
-
-
-
-
-
2
PCV System
75 +
-
-
-
-
-
2
Evap. System
75 +
-
-
-
-
-
1
Air Pump System
75 +
-
-
-
-
-
4
EGR System
75 +
-
-
-
-
-
6
New York, NY
Catalyst
84+
-
0*
0
-
-
0
(I/M-l/81, ATP-1/86)
Inlet Restrictor
84 +
-
0
0
-
-
0
PCV System
84+
-
0
1
-
-
4
Evap. System
84+
-
0
2
-
-
1
Air Pump System
84 +
-
0
0
-
-
0
EGR System
84 +
-
0
0
-
-
1
Phoenix, AZ
Catalyst
75 +
7
-
-
-
-
2
(I/M-l/77, ATP-1/87)
Inlet Restrictor
75 +
13
-
-
-
-
5
Pos. Plumbtesmo
75 +
12
-
-
-
-
1
Air Pump System
75 +
13
-
-
-
-
12
Tucson, AZ
Catalyst
75 +
-
-
-
3
-
1
(I/M-l/77, ATP-1/87)
Inlet Restrictor
75 +
-
-
-
6
-
2
Pos. Plumbtesmo
75 +
-
-
-
6
-
1
Air Pump System
75 +
-
-
-
10
-
6
*Thc rates listed for the New York survey in 1984 should not be considered representative because of the small number of 1984
model year vehicles surveyed that year.
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Motor Vehicle Tampering Survey -1988
Page 26
within the local program jurisdiction. The Houston tampering rates listed, for example,
are for Harris County vehicles only. Any non-Harris County vehicles surveyed were
excluded from this analysis.
The data in Tbble 7 suggest that the ATPs in Houston and Baton Rouge have helped
lower catalyst tampering and misfueling rates (Le., plumbtesmo, inlet restrictor).
Tampering with underhood components, however, has not declined appreciably. A
similar pattern is apparent in liable 8, where I/M + ATP programs have been generally
effective in reducing catalyst tampering and misfueling, but much less so in reducing
under- hood tampering.
This disparity in program effectiveness can be clearly seen in Figures 6(a)-(f),
where tampering rates by model year for the major components covered by inspection
programs (either ATP-only or I/M + ATP) are compared to tampering rates for the
same components on vehicles that were not covered by inspection programs. Catalyst
and inlet restrictor tampering (Figs. 6(a) and (b), respectively) are much lower on
vehicles covered by converter and inlet inspection programs than on vehicles not covered
by such inspections. Air pump system tampering (Fig. 6(c)) is moderately lower in areas
with air pump inspections than in areas without such inspections, but air pump tampering
on older vehicles is still over 20% in areas that inspect air pumps. Areas with inspection
programs for other underhood components (e.g., PCV, EGR, and evaporative systems)
do not have appreciably lower tampering rates for these components (Figs. 6(d)-(f)).
The PCV and evaporative system rates are noteworthy because these two systems control
crankcase and evaporative HC emissions, respectively — emissions which the catalytic
converter does not control. The overall tampering rates for the data presented in Figs.
6(a)-(f) are shown in Figure 7.
This weakness in inspecting underhood components may be partly due to the
nature of decentralized inspection programs. Of the eight survey sites listed in Table 7
and 8 that inspect underhood components, only three (Medford, Phoenix, and TUcson)
are centralized programs, which have historically been more effective than decentralized
programs in reducing tampering. Detecting underhood tampering is more complex and
requires more training than converter and inlet restrictor inspection. The level of
inspector training needed to implement an effective anti-tampering program is more
easily attained when vehicle inspections are conducted at a few centralized stations than
at many decentralized locations.
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Motor Vehicle Tampering Survey -1988
Page 27
Tampering (%)
30
25
20
15
10
Covered by a Program
Not Covered by a Program
88 87 86 85 84 83 82 81 80 79 78 77 76 75
Model Year
(a) Catalytic Converter
Tampering (%)
40
30
20
10
Covered by a Program
Not Covered by a Program
88 87 86 85 84 83 82 81 80 79 78 77 76 75
Model Year
(b) Inlet Restrictor
Figure 6 Comparisons of component-specific tampering rates by model year
(a—f) among vehicles both covered and not covered by ATPs.
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Motor Vehicle Tampering Survey -1988
Page 28
Tampering (%)
70
60
50
40
30
20
10
J I I I
Covered by a Program
Not Covered by a Program
88 87 86 85 84 83 82 81 80 79 78 77 76 75
Model Year
(c) Air Pump System
Tampering (%)
35
I l I .. I I I
Covered by a Program
Not Covered by a Program
88 87 86 85 84 83 82 81 80 79 78 77 76 75
Model Year
(d) Evaporative System
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Motor Vehicle Tampering Survey -1988
Page 29
Tampering (%)
30
25
20
15
10
i i i i
Covered by a Program
Not Covered by a Program
88 87 86 85 84 83 82 81 80 79 78 77 76 75
Model Year
(e) PCV System
Tampering (%)
35
30
25
20
15
10
----r l
l L
Covered by a Program
Not Covered by a Program
88 87 86 85 84 83 82 81 80 79 78 77 76 75
Model Year
(f) EGR Systems
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Motor Vehicle Tampering Survey -1988
Page 30
Component/ System
Catalytic Converter
Inlet Restrictor
Air Pump System
Evaporative System
PCV System
EGR System
8%
Tampering (%)
Component not cvrd.
by ATP inspection
Component covered
by ATP inspection
13%
Figure 7.
Comparison of component-specific
tampering rates among vehicles both
covered and not covered by ATPs.
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Motor Vehicle Tampering Survey -1988
Page 31
d. 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 switching and idle failure rates, the idle emissions from unleaded vehicles have been
tested against the cutpoints established by the I/M program where they were sampled.
Vehicles in non- I/M and ATP-only 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 8 for vehicles in the various
tampering and fuel switching categories. The failure rates for fuel switched vehicles that
were arguably tampered with or otherwise okay are based upon very small samples and
may be unreliable. The results in Figure 8 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. For example, only 16% of the unleaded vehicles surveyed that were free
of tampering and fuel switching failed an idle test, while 64% of the tampered and fuel
switched vehicles failed that test. It should be noted from Figure 8, however, that 36%
of the tampered and fuel switched vehicles were still able to pass an idle test.
Ihble 9 shows the percentage of vehicles that failed the idle emissions test for each
vehicle condition. The failure rates are listed for the entire survey, as well as in two model
year groupings representing "old" technology (1975 - 1980) and "new" technology
(1981 + ) vehicles. "New" technology includes closed loop emissions control, which came
into widespread usage in 1981 model year vehicles.
The overall percentage of tampered vehicles exceeding I/M cutpoints for HC
emissions was over three times greater than for okay vehicles (42% vs. 12%). Over four
times as many tampered vehicles exceeded CO cutpoints as did okay vehicles (45% vs.
10%). The majority (65%) of the vehicles that either had been fuel switched or had their
catalysts removed also exceeded HC or CO limits. Conversely, 35% of the vehicles with
missing catalysts or classified as fuel switched were still able to pass an idle emissions
test. A significant number of arguably tampered vehicles also produced excess idle
emissions.
The effectiveness of idle emissions testing on "new" technology vehicles can also .
be seen in Tkble 9. The data in Tbble 9 actually underestimate the impact of "new"
technology because "old" technology trucks manufactured after 1980 have been included
in the "new" technology category due to the model year split. As was found in previous
surveys, idle emissions testing is more effective in identifying tampering on 1980 and
older vehicles than on 1981 and newer vehicles. For example, 52% of the tampered "old"
technology vehicles exceeded CO cutpoints compared to 34% of the tampered "new"
technology vehicles. This suggests that idle emissions testing may not be an effective
strategy for identifying tampering and fuel switching among "new" technology vehicles,
since many vehicles with closed loop systems are able to produce low idle emissions even
with tampered emission control devices.
-------
Figure 8 Distribution of unleaded vehicles surveyed among tampering*,
misfueiing, and idle test categories.
~Excludes malfunctioning vehicles (2% of total).
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Motor Vehicle Tampering Survey -1988
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Table 9
Idle Test Failure Rates (Percent)
by Pollutant and Vehicle Condition
Vehicle Condition
Okay
Arguably Tampered
Tampered
Catalyst Removed
or Misfueled
The mean idle emissions for tampered and okay vehicles are presented in Table
10 by program type. The classification of survey sites is the same as was described in
Figure 5, with two alterations. The data from El Paso is listed in a separate category
(I/M (CO only)) because El Paso's program has no HC cutpoints. The remaining I/M
and I/M + ATP sites have been combined into the "I/M" category.
The mean idle emissions from tampered vehicles were considerably greater than
from untampered vehicles (Table 10). Overall, HC and CO emissions from tampered
vehicles were over five times greater on average than from okay vehicles. Untampered
vehicles in El Paso (which doesn't have HC cutpoints) had higher average HC and CO
emissions than vehicles in the other areas surveyed, suggesting that El Paso's program
with CO-only cutpoints may be having little impact on reducing HC or CO emissions.
Table 10
Mean Idle Emissions for Tampered and Okay Vehicles
Within Each Program Type
HC emissions (ppm) CO emissions (%)
Progran Type
Tampered
Okay
Tampered
Okay
non-I/M
360
63
3.0
0.5
I/M*
275
71
1.9
0.4
I/M (CO-
427
96
3.3
0.6
only)**
ATP-only
375
45
23
0.4
OVERALL
346
64
2.7
0.5
* Includes any program where idle emissions are checked, including I/M+ATP areas.
* * Consists of vehicles surveyed in El Paso, where only CO emissions are checked.
Failure Rate (%) by Pollutant for the Model Years listed
1975-80
1981 +
Entire
Survey (1975 + )
HC CO
HC
CO
HC
CO
HC or CO
34 32
9
8
12
10
16
40 39
15
17
27
26
35
49 52
31
34
42
45
59
48 50
43
48
46
50
65
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Motor Vehicle Tampering Survey -1988
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B. FUEL SWITCHING
1. Fuel Switching Indicators and Overlap
Fuel switching is more easily defined than measured, since no single indicator can
completely characterize 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 gram 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.
Measuring fuel switching is somewhat unusual because two of the three indicators
(positive plumbtesmo and leaded fuel in the tank) disappear with a series of subsequent
proper fuelings. Positive Plumbtesmo results disappear slowly, while leaded gasoline is
quickly diluted with subsequent tanks of unleaded fuel. A vehicle which has one or both
of these transient indicators, however, has recently used or is currently using leaded
gasoline. The presence of a tampered inlet restrictor provides no information about the
immediacy of the fuel switching. A fuel switching rate derived from the two transient
indicators would thus measure how many vehicles have recently used leaded gasoline,
while all three indicators together provide a more accurate indication of long-term fuel
switching behavior with its associated catalyst destruction and elevated emissions.
The presence of any of these three indicators suggests that a given vehicle has been
misfueled; their absence, however, does not rule it out. For example, fuel samples could
only be obtained from 75% of the unleaded vehicles surveyed, limiting the scope of this
variable. A vehicle with an untampered fuel filler inlet restrictor may also have been
fueled at a leaded pump equipped with a smaller nozzle, or by using a funnel or similar
device. The tailpipe lead test may also fail to identify misfueling, particularly if older
vehicles have had their tailpipes replaced since last operated on leaded fuel. As the lead
phasedown program has lowered lead levels in leaded gasoline, the incidence of false
negative Plumbtesmo results may be increasing. 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 Venn diagram (Figure 9(a)) illustrates the degree of overlap in the
misfueling indicators for all unleaded vehicles surveyed in 1988 where data for all three
indicators were recorded. Figure 9(b) shows the percentage of the misfueled vehicles
with each combination of the three misfueling indicators. For example, only 18% of the
misfueled vehicles exhibited all three indicators. While 68% of the vehicles having
leaded fuel in their tank also registered a positive Plumbtesmo test, only 28% 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.
The relationship between positive Plumbtesmo results and leaded fuel in the tank
can be examined by using the data from the leaded vehicles surveyed. The overlap of
these two indicators among leaded vehicles was considerable, with 80% of the leaded
vehicles that were using leaded gasoline also having a positive Plumbtesmo test. The
greater overlap for leaded vehicles would be expected, since they should have a longer
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Motor Vehicle Tampering Survey -1988
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Positive Plumbtesmo
(139 Tota
Leaded Fuel in Tank
f 107 Total)
Tampered Inlet
Restrictor
(334 Total)
(a)
Tampered Inlet Only
(54%)
Plumbtesmo + Gas (1%)
Plumbtesmo + Inlet (11%)
Leaded Gas Only (3%)
Plumbtesmo Only (6%)
All Three Indicators
(18%)
(b)
Gas + Inlet (6%)
Figure 9(a). Overlap of fuel switching indicators among raisfueled
vehicles for which all three indicators were inspected.
9(b). Breakdown of misfueled vehicles in 9(a) by prevalence
of each indicator combination.
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Motor Vehicle Tampering Survey -1988
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history of consistent leaded gasoline use. These results do suggest that Plumbtesmo is
still an effective indicator of prolonged use of leaded gasoline, even after the 90%
reduction in gasoline lead levels mandated by lead phasedown.
Figure 9(b) also shows that 90% of the fuel switched vehicles had a tampered inlet
restrictor, making it by far the most frequently observed indicator of fuel switching. A
positive Plumbtesmo result was observed on 36% of the fuel switched vehicles, while
leaded fuel was found in the tanks of 28% of the fuel switched vehicles sampled. An
antitampering program consisting of an inlet restrictor inspection and a Plumbtesmo test
would have detected fuel switching in 97% of the vehicles identified as fuel switched by
the 1988 survey.
2. Fuel Switching TV-ends
Table 11
Fuel Switching Rates among Unleaded Vehicles
by Site and Indicator
1988 Survey
Survey
Location
Leaded
Tampered
Positive
Overall Fuel
Fuel in
Inlet
Plumbtesmo
Switching
Tank (%)
Restrictor (%)
(%)
(%)
"IUcson, AZ
1
3
2
5
Phoenix, AZ
0
5
1
5
Stockton, CA
1
10
1
11
Baton Rouge, LA
3
6
3
7
Houston, TX
1
4
2
4
El Paso, TX
2
5
2
6
Albuquerque, NM
3
6
4
6
Oklahoma City, OK
5
9
4
10
San Antonio, TX
4
10
4
10
Columbia, SC
4
8
4
8
New York, NY
0
2
1
2
New Jersey
0
1
1
1
Birmingham, AL
2
6
2
6
Orlando, FL
2
9
3
8
Medford, OR
1
3
2
5
ALL SITES
2
6
2
6
Of the vehicles requiring unleaded fuel, 6% were identified as misfueled by at least
one of the indicators discussed above. The fuel switching incidence by survey site is listed
in Table 11. The data in Ibble 11 again show that inlet restrictor tampering is easily the
most prevalent indicator of misfueling. This is not surprising, since inlet tampering is
the most persistent indicator of past misfueling, even when the vehicle has been properly
fueled for some time.
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Table 12
Combined Tampering and Fuel Switching
1988 Survey
Survey
Location
Catalyst-equipped vehicles
with catalysts removed or
that were fuel switched (%)
Unleaded Vehicles
either tampered or
fuel switched (%)
TUcson, AZ
6
22
Phoenix, AZ
6
22
Stockton, CA
12
22
Baton Rouge, LA
8
21
Houston, TX
4
17
El Paso, TX
8
21
Albuquerque, NM
6
20
Oklahoma City, OK
11
20
San Antonio, TX
12
26
Columbia, SC
9
20
New York, NY
4
15
New Jersey
2
8
Birmingham, AT,
7
18
Orlando, FL
10
21
Medford, OR
3
12
ALL SITES
8
19
Thble 12 presents the combined tampering and fuel switching rates for the 1988
survey. The percentage of unleaded vehicles that were tampered or fuel switched was
19%, and the percentage of unleaded vehicles with missing or damaged converters was
8%. Ihble 12 thus suggests that over 40% of all tampering and fuel switching is composed
of vehicles in the catalyst removed or fuel switched category. Since these conditions have
the largest emissions impact, this indicates the very serious nature of much tampering.
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Table 13
Prevalence of Fuel Switching Indicators by Program Type
Percentage by Program Type
Fuel Switching Indicator
non-I/M
ATP-only
I/M + ATP
Tampered Inlet Restrictor
9
2
2
Positive Plumbtesmo
4
1
1
Leaded Fuel in Tank
3
1
0
Overall Fuel Switching
10
3
3
Ibble 13 presents the prevalence of each fuel switching indicator by program type.
The classification of survey sites is the same as was described in Figure 5, with two
alterations. For this analysis the 1975 -1979 model year vehicles surveyed in Houston
were reclassified from "ATP-only" to "non-I/M" because Houston's program does not
inspect the fuel switching indicators for these model years. The same model years of
vehicles surveyed in El Paso are also not inspected with regard to these fuel switching
indicators but are still covered by the I/M test; thus the 1975 -1979 El Paso vehicles were
reclassified from "I/M + ATP" to "I/M-only." Tbble 13 shows that the prevalence of each
fuel switching indicator was considerably greater in the non-I/M areas than in the
ATP-only or I/M + ATP areas. (The I/M-only rates are not included in Thble 13 because
of their lack of validity, as was discussed earlier.)
3. Fuel Switching hv Vehicle TVpe
Table 14
Prevalence of Fuel Switching Indicators by Vehicle Type
Percent Fuel Switching by Vehicle Type
Fuel Switching Indicator
LDV
LDT
Tampered Inlet Restrictor
5
7
Positive Plumbtesmo
2
4
Leaded Fuel in Tank
2
3
Overall Fuel Switching
6
8
The prevalence of each fuel switching indicator by vehicle type is presented in
Thble 14. Overall fuel switching among trucks was slightly higher than for passenger cars
(8% vs. 6%) and the prevalence of each indicator was higher in trucks as well.
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4. Fuel Switching and Catalyst Tampering
Consumers and mechanics remove catalytic converters for a number of reasons,
but some of their motivation may be 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 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.
Figure 10 depicts the degree of overlap between catalyst removal and fuel switch-
ing. Vehicles with catalyst tampering exclusive of fuel switching were relatively uncom-
mon — only 40% of the catalyst tampered vehicles were not fuel switched. Fuel switching,
however, is not always accompanied by catalyst removal, since the majority (57%) of the
fuel switched vehicles still had their catalysts.
Figures 11(a) and (b) examine the relationship between converter tampering and
two of the three misfueling indicators (positive Plumbtesmo and tampered inlet restric-
tor). Only vehicles that have been subject to an ATP with Plumbtesmo testing and in
which all three of these parameters were inspected are included in these figures. These
three parameters have been incorporated into a number of antitampering programs to
determine if a converter is missing or damaged. A vehicle failing the Plumbtesmo test
or inlet restrictor inspection in some of these programs (e.g., Texas) is required to have
its converter replaced.
Figure 10 Overlap of catalyst tampering and fuel switching
among catalyst-equipped vehicles - 1988 survey.
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Page 40
Positive Plumbtesmo
(129 Total)
Missing Catalytic
Converter
(269 Total)
Tampered Inlet
Restrictor
(317 Total)
(a)
Tampered Inlet Only (27%)
Plumbtesmo + Cat. (<1%)
Cat. + Inlet (20%)
Catalyst Only (23%)
Plumbtesmo Only (4%)
All Three Indicators (18%)
^ Inlet + Plumbtesmo (7%)
Figure 11(a) Overlap of indicators used by ATPs to detect missing/damaged
catalysts. Only includes vehicles for which all three indicators
were inspected and are not covered by an ATP with plumbtesmo
testing.
Figure 11(b) Breakdown of vehicles in 11(a) by prevalence of each indicator
combination.
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Motor Vehicle Tampering Survey -1988
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Figure 11(a) shows the value of these programmatic criteria in detecting missing
or lead-poisoned converters. A simple inspection of the converter, for example, would
catch 62% of the vehicles with missing or lead-poisoned converters. Inspecting both the
converter and inlet restrictor, however, would detect 96% of these vehicles. The
usefulness of Plumbtesmo in detecting damaged converters appears to be limited, since
only 4% of the vehicles in Figure 11(b) failed for Plumbtesmo only. In 1984, prior to the
sharp declines in gasoline lead levels, 17% of the vehicles failing one of these program-
v matic criteria failed for Plumbtesmo only. Plumbtesmo may still be effective, however,
in deterring fuel switching.
5. Gasoline Lead Concentrations
Of the vehicles identified as misfueled by any of the three misfueling indicators,
72% 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 inlet restrictor
and/or a positive Plumbtesmo test. Figure 12 presents the distribution of lead concentra-
tions of 0.05 gpg or more in misfueled vehicles for the 1984 -1988 surveys. The impact
of lead phasedown can be dramatically seen in Figure 12. Not only has the overall
prevalence of leaded gas in unleaded vehicles declined (as shown by the decreasing
overall height of the bars), but the distribution of lead concentrations in the leaded
gasoline has shifted dramatically. In the 1988 survey, for example, less than 1% of the
misfueled vehicles had a gasoline lead concentration of 0.2 gpg or higher, compared to
17% in 1987 and 53% in 1984.
As was mentioned earlier, the 1988 survey was the first in which gasoline samples
were taken from leaded vehicles as well as unleaded vehicles. A significant percentage
(28%) of the leaded vehicles were using unleaded gasoline at the time they were
surveyed, either by the vehicle owner's choice or because service stations were marketing
"leaded" gasoline that actually contained less than 0.05 gpg of lead. The distribution of
lead concentrations among the remaining 72% is consistent with the distribution of lead
concentrations found in the misfueled unleaded vehicles. While this would be expected,
it also suggests that the addition of concentrated lead additives to the gas tank by
consumers is not widespread.
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Motor Vehicle Tampering Survey -1988
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Percentage of Misfueled Vehicles
100
lead concentration
range (gpg.)
j7"] 1.000+ gpg
[2] 0.800 - 0.999
|| 0.600 - 0.799
3 0.400 - 0 599
U 0.200 - 0 399
Q 0.100 - 0 199
¦ 0.050 - 0 099
1984 1985 1986 1987
Survey Year
1988
Figure 12 Distribution of lead concentrations in leaded fuel
sampled from fuel switched vehicles: 1984 - 88
surveys. Percentages based on all fuel switched
vehicles, including those using unleaded fuel
(<0.05 gpg).
-f
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Motor Vehicle Tampering Survey -1988
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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.
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:
APPENDIX B
SURVEY AND DATA RECORDING PROCEDURES
1. Explanation of Survey Forms
0 - Not originally equipped
1 - Functioning properly
2 - Electrical disconnect
3 - Vacuum disconnect
4 - Mechanical disconnect
5 - Incorrectly routed hose
6 - Disconnect/Modification
7 - Missing item
8 - Misadjusted item
9 - Malfunctioning
A - Stock equipment
B - Non-stock
D - Add on equipment
Y-Yes
Z-No
Additional codes were used for those components which could not be classified into
the above categories. If a determination could not be made about a given component's
condition, the variable was left blank. A brief description of each data entry follows.
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Motor Vehicle Tampering Survey -1988
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Form A - Underhood
1-4 ID Number - Vehicles are numbered sequentially as they are inspected. This num-
ber is preceded by a site identifying number
5-8 Month and year of last I/M inspection (left blank if vehicle is licensed in non-I/M
area).
9-12 Manufacturer of vehicle
13-23 Engine Family - as recorded on the underhood emission label.
24-34 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.
35-38 Displacement - as recorded on the underhood emission label.
39-40 Vehicle Model Year
41 Originally Catalyst Equipped - as recorded on the underhood emission label or the
driver's door post.
42 Engine Status - is coded 'Y' if the engine is the one originally installed in the vehicle
and is coded 'Z' if the vehicle: has a different gasoline engine than was originally
equipped, was originally equipped with a diesel engine and currently has a
gasoline engine, was converted to operate on a fuel other than gasoline or diesel
fuel (i.e., propane), or is a "gray market" imported vehicle.
43 Air Cleaner - is coded 'A', 'B', or T.
44 Heated Air Intake - provides warm air to the carburetor during cold engine opera-
tion. The heated air intake is coded '0', '1', '3', '4', T (stovepipe hose), '9'
(vacuum override), or 'B' (custom air cleaner).
45 Positive Crankcase Ventilation (PCV) system - prevents crank case emissions by purg-
ing 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 T, 3', '4' (fresh air hose), T, '9', or 'B' (includes fuel economy devices).
46 Turbocharger - coded '0', 'A', 'B', or 'D\
47 Evaporative Control System (ECS) - controls vapors from the fuel tank and car-
buretor. 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
T, *3' (carburetor line), '4' (tank line), '5', '6' (air cleaner unsealed), T, or '9'
(cracked hose or canister).
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Motor Vehicle Tampering Survey -1988
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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 commonly located in the air cleaner to supply air to the exhaust
manifold.
48 Aspirated Air Injection System (PAIR) - coded '0' (if air pump system or none), '1',
'4', T, or '9\
49 Air Pump Belt - is coded '0' (if PAIR or none), '1', T, or '8' (loose belt).
50 Air Pump System - for the purposes of this variable, consists of the air pump and con-
trol valve and is coded '0' (if a PAIR or none), '1', '4' (other than belt removal),
T, or '9'(frozen pump).
51 Exhaust Manifold - coded 'A' or 'B'.
52 Oxygen and Related Sensors • The oxygen sensor controls the air-fuel mixture going
into the engine of vehicles equipped with three-way catalytic converters. A
vehicle's computerized engine and emissions control system receives input from
various sensors for engine condition information, and constantly adjusts the
air/fuel ratio, distributor, and emissions devices for optimum economy,
driveability, and emissions. These sensors are coded '0', '1', '2', '4' (unscrewed),
'6', or T.
53 Carburetor Type - is coded 'F (fuel injected), 'A' (stock carbureted), or 'B' (non-
stock carbureted).
54 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 stand-
ard 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. The EGR system is
coded '0', T, '2', '3', '4', '5', T, or '9'.
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Form B - Rear
1-4 ID Number - Same as on Form A.
5-8 Make
9-12 Model
13 Vehicle Type - coded as follows: C = car, T = truck
14-15 License Plate - State abbreviation
16-19 Program Jurisdiction - the city or county of the vehicle's registration is entered (if the
vehicle is covered by a control program).
20-23 Exhaust gas HC concentration (in ppm) at curb idle.
24-26 Exhaust gas CO concentration (in percent) at curb idle.
27-29 Odometer - mileage in thousands
30 Dash Label - displays the fuel required and is coded 'O'(for leaded vehicles), '1', or '7'.
31 Catalytic Converter - oxidizes the HC and CO to water and C02 in the exhaust gas.
Later model catalysts also reduce oxides of nitrogen. The converter is coded '0',
'1', T (entire catalyst canister removed), or 'B' (aftermarket catalyst present).
32 Exhaust System - if as originally equipped an 'A' is coded. If non-stock a "B' is coded.
33 Exhaust System Integrity - the condition of the exhaust system is coded '1' (no ob-
vious leaks) or '9' (leaks evident).
34 Tank Cap - seals the fuel tank during normal operating conditions and is coded '1',
T, or '9' (loose cap). A separate entry is made to indicate whether the tank cap is
stock or non-stock ('A' or 'B').
35 Tank Cap Origin - is coded 'A' if the tank cap is a stock cap. The cap is coded 'B' if it
is non-stock.
36 Tank Label - displays required fuel and is coded '0' (for leaded vehicles), '1', or
37 Filler Neck Restrictor • The restrictor is designed to prevent the introduction of
leaded fuel into a vehicle requiring unleaded fuel. It is coded '0' (for leaded
vehicles), '1', '4' (widened), '6' (nozzle adaptor present), 'T, or 'B' (non-stock
inlet restrictor-functioning properly).
38 Plumbtesmo - Plumbtesmo paper is used to check for the presence of lead in vehicle
exhaust pipes. A positive indication is coded as 'P' and a negative as 'N\
39 Fuel Sample - indicates if inspector was able to obtain fuel sample for later lead
analysis ('V or 'Z').
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Motor Vehicle Tampering Survey -1988 Page 47
2. Classification of Component Conditions
The table below was used to classify the various system components as tampered
(T), arguably tampered (A), or malfunctioning (M). 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.
Codes from forms A and B
Component/system 23456789B
Dash Label A
Tank Cap A M
Tank Label A
Filler Neck Restrictor T T T
Catalytic Converter T
Oxygen and Related Sensors T T T T
PCV System T T T M T
Heated Air Intake T A A M T
Evaporative Control System T T T T T M
Aspirated Air Injection System T T M
Air Pump Belt T M
Air Pump System T T M
EGR System T T T T T M
T = Tampered
A = Arguably tampered
M = Malfunctioning
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Motor Vehicle Tampering Survey-1988 Page 48
3. Fuel Sample Collection and Labeling Procedures
An attempt was made to take a fuel sample from each vehicle surveyed. These
samples were collected in two-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. The bottles were packed, labeled, and shipped to EPA's Motor Vehicle
Emissions Laboratory in Ann Arbor according to the shipper's requirements.
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 con-
tamination.
3) After removing the test paper, determine whether a color change has occurred. Red
or pink coloration indicates the presence of lead.
5. Field Quality Control
Reference and calibration gases were used to ensure the accuracy of the emissions
analyzer. Horiba gases certified by RTP 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.
Two 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 RTP reference gases. Their
approximate compositions were:
8% CO
1560 ppm HC (Hexane equivalent)
1.6% CO
320 ppm HC (Hexane equivalent)
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Motor Vehicle Tampering Survey -1988
420-R-89-100
Page 49
APPENDIX C
EMISSION OUTPOINTS FOR I/M AREAS
The table below lists the emission cutpoints used in 1988 by the I/M areas covered
in the 1988 tampering survey. The cutpoints for pre-1975 vehicles are not included, since
these vehicles were not surveyed.
Survey Site
Model Year
Emissions Cutpoints
CO (%) HC (ppm)
El Paso, TX
1975-77
1978
1979
1980
1981 +
7.5
6.5
6.0
4.0
1.2
Tucson/Phoenix, AZ
1975-78 (4 cyl.)
2.2
250
1975-78 (6-8 cyl.)
2.0
250
1979 (4 cyl.)
2.2
220
1979 (6-8 cyl.)
2.0
220
1980+ (all)
1.2
220
New York, NY
1975-78
3.5
400
1979-80
2.5
300
1981 +
1.2
220
New Jersey
1975-80
3.0
300
1981 +
1.2
220
Medford, OR
1975-80 (no CC)
25
250
1975-80 (CC)
0.5
175
1981 +
0.5
175
KEY: CC = catalytic converter (all types), CYL. = cylinder
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