UNITED STATES ENVIRONMENTAL PROTECTION AGENCY …

 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
               WASHINGTON, D.C. 20460

                                                                       OFFICE OF
                                                                    ENFORCEMENT AND
                                                                  COMPLIANCE ASSURANCE

                                        September 4, 1997


                  Addendum to Mobile Source Enforcement Memorandum 1A

SUBJECT:        Tampering Enforcement Policy for Alternative Fuel Aftermarket Conversions

A. Purpose The purpose of this document is to clarify and revise the U.S. Environmental
Protection Agency's (EPA's) "tampering" enforcement policy for motor vehicles and motor
vehicle engines originally designed to operate on gasoline or diesel fuel and subsequently
modified to operate exclusively or in conjunction with compressed natural gas (CNG) or liquified
petroleum gas (LPG or propane), hereinafter referred to as "alternative fuels". The provisions of
this Addendum shall apply to all persons subject to the tampering prohibition of Section 203(a) of
the Act. For the purpose of this policy Addendum, the term "manufacturer" will apply to any
person who designs, produces, and/or assembles components for converting vehicles or engines to
operate on alternative fuels and is responsible for complying with all applicable requirements of
this policy Addendum.

B. Background: EPA's policy is and has been that any alteration from an original configuration
of a vehicle or engine as certified under Title II of the Act may constitute tampering under Section
203(a)(3). Routine maintenance and repair of vehicles and engines requires the use of
replacement parts which may be non-original or "aftermarket" parts or systems. EPA's Office of
Enforcement and General Counsel issued Mobile Source Enforcement Memorandum 1A (Memo
1A) on June 25, 1974 to provide guidance to covered parties regarding how the Agency intended
to enforce the "tampering" prohibition under Section 203(a)(3) of the Clean Air Act (Act) with
respect to maintenance and the use of aftermarket parts.

        Memo 1A provides, in part, that the use of an aftermarket part, alteration or add-on part
will not constitute tampering if the dealer has a "reasonable basis" to believe that such acts will
not adversely affect emissions performance. It also provides specific procedures or options by
which the dealer would have a "reasonable basis". One available procedure is emissions testing
performed in accordance with "40 CFR 85" (subsequently revised and incorporated under 40
CFR Part 86) demonstrating compliance with emission standards for the useful life of the vehicle
or engine. An alternate option is that "a Federal, state or local environmental control agency
represents that a reasonable basis exists" based on testing done in accordance with procedures
specified by that agency. Many vehicles converted from gasoline fueled to CNG or propane have
relied on the second option utilizing procedures established by California or Colorado for
demonstrating emissions compliance.
        EPA has recently become aware of federal emission test data generated under a program
conducted by the National Renewable Energy Laboratory (NREL) which indicate that a
significant number of these vehicles modified to run on alternative fuels may be exceeding one or
more applicable federal emission standards. The installers involved in the NREL program had
attempted to comply with Memo 1A by using conversion systems certified by the state of
California under the "California Exhaust Emission Standards and Test Procedures for Systems
Designed to Convert Motor Vehicles Certified for 1993 and Earlier Model Years to Use
Liquefied Petroleum Gas or Natural Gas Fuels" (pre-1994 California Procedures). EPA has
subsequently reviewed emission test data from other sources which generally substantiate the
NREL results.

          In response to concerns raised by these data, the Agency conducted a public stakeholders
meeting on February 21, 1997, with representatives of the affected industries, regulatory agencies
and interested fleet operators. The purpose of the meeting was to discuss these data and the
causes of the emission failures as well as to explore all available options to identify and remedy
the problems. Many reasons were provided for the emission problems, including inadequate
initial testing, insufficient durability evaluations, overly broad vehicle application based on limited
testing, inadequate systems/parts specifications, improper installation and fuel variability. The
concerns of the affected industries and fleets subject to several alternative fuel statutory mandates
were also discussed.

        The most significant conclusion reached at that meeting, and from extensive data review
and discussions subsequent to that meeting, was that the pre-1994 California and Colorado
procedures as currently structured do not provide an adequate demonstration or assurance that a
vehicle or engine modified to operate on an alternative fuel using an aftermarket conversion
system will comply with the applicable emission standards for its useful life. As a result of the
above and in light of the number of vehicles and engines that may be converted to alternative fuels
in the near future, EPA believes it is appropriate to issue this Addendum to Memo 1A (this
Addendum) to provide additional guidance to the regulated community, including manufacturers
and installers of alternative fuel conversion systems.

C. Revised Policy: Effective immediately, EPA will no longer accept a representation based on
the pre-1994 California Procedures for alternative fuel conversion systems or on the test
procedures under Colorado Regulation No. 14 in effect prior to the date of this Addendum as a
"reasonable basis" under paragraph 3(c) of Memo 1A. Consequently, any future installation of
an alternative fuel conversion system, or the modification of any motor vehicle or motor vehicle
engine in compliance with Title II of the Clean Air Act to operate exclusively or in part with an
alternative fuel, or the causing thereof, may constitute tampering under Section 203(a) of the Act,
where the installer or manufacturer has relied exclusively on a representation by Colorado or
California, as described above, that a reasonable basis exists in accordance with paragraph 3(c) of
Memo 1A. Effective immediately, the "reasonable basis" under paragraph 3 of Memo 1A that
EPA agrees may be relied on by any person, including a manufacturer, installer or operator, when

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converting, or causing the conversion of, a motor vehicle or motor vehicle engine to operate on
an alternative fuel is limited to one of the three options listed below.

       1.      A Federal Certificate under 40 CFR Part 86 demonstrating compliance with the
applicable standards or under 40 CFR Part 88 demonstrating compliance with Clean Fuel Fleet
standards for each engine family to be converted in accordance with 40 CFR Part 85, Subpart F;
or

        2.     A Retrofit System Certification under the "California Certification and Installation
Procedures For Alternative Fuel Retrofit Systems for Motor Vehicles Certified for 1994 and
Subsequent Model Years" for a conversion system installed and tested under the above
procedures on a vehicle or engine from a "50-state engine family" for use nationwide, or for a
conversion system installed and tested under the above procedures on a vehicle or engine from a
"California engine family" for use in California only; or

       3.       Until December 31, 1998, the use of an alternative fuel conversion system
designed, tested and installed on a single engine family, or multiple engine families as provided
under paragraph 4.b.(3) below, if testing is completed by March 31, 1998, as follows:

                a.      With the alternative fuel conversion system installed on the certified engine
family, the manufacturer shall perform, or cause the performance of, one federal emission test
while operating with the alternative fuel and one test with the original certification fuel, if dual
fuel operation is retained, in accordance with the applicable test procedures under 40 CFR Part 86
or Part 88 for that class and model year vehicle or engine. Prior to testing, the vehicle or engine
shall be operated with the conversion system installed for at least the number of miles or hours
equal to the service accumulation period needed to stabilize the emission control system specified
by the original manufacturer in its certificate application submitted to EPA. EPA encourages
manufacturers to conduct at least one baseline emission test with the certification fuel prior to
conversion to ascertain that the vehicle or engine meets the applicable standards.

                b.       (1) With the application of an appropriate deterioration factor (DF) to the
above test results, the vehicle or engine shall meet the applicable federal exhaust emission
standards to which the vehicle or engine was originally certified. The DF shall be determined
either based on full useful life durability testing, predictions based on engineering judgement for a
similar light duty vehicle or heavy-duty engine with a similar emission control system using the
same alternative fuel conversion system, or determined in accordance with the appropriate
protocol contained in the "Dear Manufacturer" letter of September 27, 1995 - Assigned
Deterioration Factors for Gaseous-Fueled Vehicles and Engines, identified as CD-95-14. For
heavy-duty engines with aftertreatment (such as a catalyst), the deteriorated emissions are
calculated by multiplying the DF with the exhaust emission results. For heavy-duty engines


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without aftertreatment, the deteriorated emissions are calculated by adding the DF with the
exhaust emission results. For a vehicle or engine converted and tested prior to accumulating 50%
of its useful life, the manufacturer shall apply the full DF. For a vehicle or engine converted and
tested subsequent to accumulating 50% of its full useful life, apply a DF that is the midway point
between no DF and the full DF. For example, an additive DF of 1.0 may become 0.5 and a
multiplicative DF of 2.0 may become 1.5. For a vehicle or engine converted and tested
subsequent to accumulating its full useful life, apply no DF.

                       (2)     For heavy-duty engines used in vehicles with a gross vehicle weight
rating (GVWR) less than or equal to 10,000 lbs, the manufacturer may demonstrate compliance
with the applicable light-duty truck standards in accordance with the preceding paragraph.

                        (3)      In lieu of engine dynamometer testing for on-highway heavy duty
vehicles with a GVWR less than or equal to 14,000 lbs, the manufacturer may conduct two or
three emission tests as described below in accordance with the most current amendments to
"California Exhaust Emissions Standards and Test Procedures for 1988 and Subsequent Model
Passenger Cars, Light-Duty Trucks and Medium-Duty Vehicles". These shall consist of one
baseline test using the certification fuel prior to conversion, one test after conversion with the
alternative fuel and one test after conversion with the certification fuel if the vehicle is intended to
be dual fuel. The two tests after conversion shall not result in any exhaust emissions that exceed
1.10 times any of the baseline emission levels. In the case of pure CNG operation, the after
conversion NMHC emissions shall not exceed 0.9 times the THC emissions before conversion.
For heavy-duty vehicles operating on a mixture of CNG and either diesel fuel or gasoline, the
conversion system manufacturer should contact EPA's Mobile Source Enforcement Branch to
determine the appropriate ratio of NMHC emissions after conversion to THC emissions before
conversion.

                       (4)     With respect to light duty vehicles, light duty trucks, or heavy-duty
engines meeting the requirements of paragraph (2) above, the above demonstration may be
applied as a reasonable basis for up to a maximum of three additional light duty engine families to
that tested, provided:

              A.     The results from testing done in accordance with the above procedures
demonstrate compliance with low emission vehicle (LEV) or more stringent emission standards
under 40 CFR § 88.104,

                B.      The additional engine families have engine displacements equal to, or
within 0.8 liters (50 CID) less than, the engine tested,

                C.      The additional engine families comprise vehicles equal to or less than the


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gross vehicle weight of the vehicles covered by the engine family tested, and

               D.       The additional engine families are equipped with the same catalytic
converter type (i.e. beaded vs monolith, OC vs OC/RC) and the same primary emission control
technology (eg. EGR, Air Injection, EFI vs carburetor, closed loop vs open loop) as the engine
family tested.

                        (5)   Option 3 of this policy is not available for conversion of California
only engine families.

                      (6)    An alternative fuel conversion system that degrades a closed loop
feedback system to a continuous non-feedback open loop system is not allowed under this option.

                      (7)     Compliance with this policy may be demonstrated based on existing
data provided such data are the result of testing in accordance with the procedures and protocols
specified herein.

                       (8)    Demonstration with the Cold CO requirements under 40 CFR Part
86 Subpart C is not required under Option 3 of this policy.


                       (9)   The Certification Short Test requirements under 40 CFR Part 86,
Subpart O is not required under Option 3 of this policy.

                      (10) The evaporative emissions requirements under 40 CFR 86.094-8(b)
and 86.094-9(b) are not required under Option 3 of this policy.

                c.      The manufacturer of the conversion system shall specify all part
numbers/calibrations associated with that conversion system and provide all such information,
specifications and installation requirements, including a permanent conversion system label which
appropriately identifies the conversion system with reasonable specificity, with each system that is
sold or provided for installation.

                 d.      In order to demonstrate that it has a reasonable basis to believe that its
conversion system will not adversely affect emissions over the useful life of the vehicle or engine,
the conversion system manufacturer should retain records including but not limited to all emission
test data, including test results, description of vehicles and/or engines modified, all maintenance
and modifications performed, laboratory data sheets, identification of test laboratory, test dates,
test personnel and test procedures followed, engine families tested, data to support additional
engine family coverage, if applicable, VIN's, vehicle and engine mileage and/or age as applicable,


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fuel specifications, conversion system part numbers and calibrations, durability procedures
followed including all durability data and all calculations and engineering analyses performed to
determine compliance with the above requirements.

               e.      In order to meet the requirements of this policy, any installation of a
conversion system designed and tested in accordance with the above shall be done in accordance
with the applicable part numbers/calibrations installed on the vehicle or engine that was tested,
completed in accordance with manufacturer's specifications and/or instructions and the
conversion system label affixed to the vehicle or engine. The system shall only be installed on a
vehicle or engine of the same engine family as that tested or as permitted under paragraph 3.b.(3)
above.

               f.       In support of an appropriate installation, the installer should retain records
of each vehicle or engine converted in accordance with the above, including the VIN, make and
year of each vehicle or engine so modified, the name of the installer, the date of installation and a
copy of the manufacturer's or marketer's/distributor's representation that the conversion system
has been demonstrated on that engine family to meet the requirements of this policy
               g.       In support of any marketer's or distributor's compliance with the
requirements of this policy, such parties should retain records of each conversion system sold or
distributed, copies of the representation from the manufacturer that the system meets this policy
and records of sales to others including the name of the purchasers, part numbers, dates of sales
and the numbers of systems sold.

                h.      Colorado has indicated that it will revise its administrative procedures
under Colorado Regulation No. 14 to require that conversion system manufacturers conduct
testing in accordance with option 3 of this Addendum in order to receive a Colorado Letter of
Certification. Consequently, until December 31, 1998, EPA will not consider as tampering the
sale and installation of a conversion system in Colorado pursuant to a Colorado Letter of
Certification issued after the above-referenced administrative procedure revisions have been made
by Colorado, provided testing in support of the Letter of Certification is done in accordance with
option 3 of this Addendum and is completed by February 28, 1998.


D. Conclusion: EPA believes that the maximum degree of assurance that vehicles or engines
modified to operate on alternative fuels will meet emissions standards throughout their useful life
can only be achieved through full certification demonstration in accordance with 40 CFR Parts 86
or 88. However, the cost and time associated with such a demonstration may be prohibitive for
some conversion system manufacturers in the short term and may not provide sufficient
equipment for fleets currently subject to various alternative fuel mandates to comply with those
mandates. In addition, EPA will be attempting to implement various procedures to streamline


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federal certification for alternative fuel vehicles and on-highway engines, but it is likely that
implementation of those procedures will take some time. In the interim, the procedures and
requirements outlined in option 3 above should allow alternative fuel conversion systems to be
developed and evaluated more quickly and at less cost, while providing a reasonable assurance
that emissions will not be deteriorated. After December 31, 1998, manufacturers, marketers and
installers must utilize equipment which meets the requirements of option 1 or option 2 above to
be covered by the non-tampering policy of Memo 1A.

        EPA will be reviewing Memo 1A more thoroughly in the near future to determine if
additional changes are required for other vehicle or engine modifications, parts or systems. Any
questions regarding this interim policy should be directed to the Mobile Source Enforcement
Branch at (202) 564-2255.


                                             /s/

                                   Bruce C. Buckheit, Director
                                    Air Enforcement Division
                        Office of Enforcement and Compliance Assurance




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