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Virginia Administrative Code
Title 9. Environment
Agency 5. State Air Pollution Control Board
Chapter 91. Regulations for the Control of Motor Vehicle Emissions in the Northern Virginia Area
9/26/2020

9VAC5-91-430. Asm Test Procedure.

A. The ASM equipment shall be in proper operating condition according to the manufacturer's instructions prior to initiating a test.

1. The vehicle shall be maneuvered onto the dynamometer with the drive wheels positioned on the dynamometer rolls. Prior to test initiation, the rolls shall be rotated until the vehicle laterally stabilizes on the dynamometer. Vehicles that cannot be stabilized on the dynamometer shall be rejected from testing. Drive wheel tires shall be dried if necessary to prevent slippage.

2. Prior to initiating the ASM exhaust test procedure:

a. Vehicles that are also required to receive OBD testing shall be connected to the appropriate test equipment and vehicle and analyzer system manufacturer instructions.

b. The OBD test, if applicable, shall be performed prior to the ASM test.

3. When ambient temperatures exceed 72°F, testing shall not begin until the cooling fan is positioned and activated. The cooling fan shall be positioned to direct air to the vehicle cooling system, but shall not be directed at the catalytic converter.

4. Testing shall not begin until the vehicle is properly restrained for ASM testing.

5. Testing shall not begin until the exhaust ventilation system is properly functioning and attached or positioned as necessary.

6. To ensure that the motor vehicle and the dynamometer are in a warmed-up condition prior to official testing, a 30-90 second preconditioning, as determined by the department, shall be performed using the ASM 2525 load simulation.

7. Prior to each test or mode of a test, the analyzer system shall automatically select the load setting of the dynamometer.

8. Engine speed shall be monitored by means of an RPM sensor and recorded in the test record.

B. The test sequence shall consist of first chance and, if applicable, second chance tests in both ASM modes described in this section. Vehicles that fail the first chance test as described within 150% of the standard shall receive a second chance test. The department may increase this percentage to 200% when interim or final standards take effect according to 9VAC5-91-170 B. The second chance test shall consist of a repetition of the mode or modes that were failed in the first chance test. The department may eliminate the need to do a second chance test if the vehicle has already failed an emissions component check.

C. The ASM 2525 mode timer shall start when the dynamometer speed (and corresponding power) are maintained at 25 ±1.0 miles per hour for five continuous seconds. If the acceleration simulation exceeds the tolerance specified by the analyzer system equipment manufacturer for more than five consecutive seconds after the mode timer is started, the test mode timer shall be reset. Should this happen a third time, the test shall be aborted and another started. The dynamometer shall apply the required torque load for 25.0 mph at any testing speed within the tolerance of 25 ±1.0 miles per hour (i.e., constant torque load over speed range). The torque tolerance shall be ±5.0% of the correct torque at 25 mph.

1. The analyzer system shall automatically select the proper load setting for the dynamometer and test standards, based on the Equivalent Test Weight (ETW) and the look-up table in Part XIV (9VAC5-91-790 et seq.), using vehicle identification information.

2. If the dynamometer speed or torque falls outside the speed or torque tolerance for more than two consecutive seconds, or for more than five seconds total, the test mode time shall reset to zero and resume timing. The minimum mode length shall be 45 seconds. The maximum mode length shall be 90 seconds elapsed time.

3. During the 10 second period used for the pass/fail decision, dynamometer speed shall not fall more than 0.5 mph (absolute drop, not cumulative). If the speed at the end of the 10 second period is more than 0.5 mph less than the speed at the start of the 10 second period, testing shall continue until the speed stabilizes enough to meet this criterion.

4. The pass/fail analysis shall begin after an elapsed time of 30 seconds, which may include up to 15 seconds of the preconditioning time period if the ASM 2525 torque and speed tolerances are maintained. A pass or fail determination shall be made for the vehicle and the mode shall be terminated as follows:

a. The vehicle shall pass the ASM 2525 mode and the mode shall be immediately terminated if, at any point between an elapsed time of 30 seconds and 90 seconds, the 10 second running average measured values for each pollutant are simultaneously less than or equal to the applicable test standards described in Part XIV (9VAC5-91-790 et seq.).

b. The vehicle shall fail the ASM 2525 mode and the mode shall be terminated if subdivision C 4 a of this section is not satisfied by an elapsed time of 90 seconds.

5. Upon termination of the ASM 2525 mode, the vehicle and dynamometer shall immediately begin a transition to the speed required for the ASM 5015 mode. The dynamometer torque shall smoothly transition during the transition period and shall automatically reset to the load required for the ASM 5015 mode as specified in subdivision D 1 of this section.

D. The ASM 5015 mode timer shall start when the dynamometer speed (and corresponding power) are maintained at 15 ±1.0 miles per hour for five continuous seconds. If the acceleration simulation exceeds the tolerance specified by the analyzer system manufacturer for more than five consecutive seconds after the mode timer is started, the test mode timer shall be reset. Should this happen a third time, the test shall be aborted and another started. The dynamometer shall apply the required torque for 15.0 mph at any testing speed within the tolerance of 15 ±1.0 miles per hour (i.e., constant torque load over speed range). The torque tolerance shall be ±5.0% of the correct torque at 15 mph.

1. The analyzer system shall automatically select the proper load setting for the dynamometer and test standards, based on the ETW and the look-up table in Part XIV (9VAC5-91-790 et seq.), using vehicle identification information.

2. If the dynamometer speed or torque falls outside the speed or torque tolerance for more than two consecutive seconds, or for more than five seconds total, the mode timer shall reset to zero and resume timing. The minimum mode length shall be 40 seconds. The maximum mode length shall be 90 seconds elapsed time.

3. During the 10 second period used for the pass/fail decision, dynamometer speed shall not fall more than 0.5 mph (absolute drop, not cumulative). If the speed at the end of the 10 second period is more than 0.5 mph less than the speed at the start of the 10 second period, testing shall continue until the speed stabilizes enough to meet this criterion.

4. The pass/fail analysis shall begin after an elapsed time of 30 seconds. A pass or fail determination shall be made for the vehicle and the mode shall be terminated as follows:

a. The vehicle shall pass the ASM 5015 mode if, at any point between an elapsed time of 30 seconds and 90 seconds, the 10-second running average measured values for each pollutant are simultaneously less than or equal to the applicable test standards described in Part XIV (9VAC5-91-790 et seq.). If the vehicle passed the ASM 2525 mode, the ASM 5015 mode shall be terminated upon obtaining passing scores for all three pollutants.

b. The vehicle shall fail the first chance ASM 5015 mode if subdivision D 4 a of this section is not satisfied by an elapsed time of 90 seconds.

E. The inspector shall perform a second chance test on vehicles which fail either mode of the previous test sequence as follows:

1. If the vehicle fails the first-chance test, the test timer shall reset to zero and a second-chance test shall be performed, except as noted below. The second-chance test shall have an overall maximum test time of 145 seconds if one mode is repeated, an overall maximum time of 290 seconds if two modes are repeated.

2. If the vehicle failed only the ASM 2525 mode of the first chance test, then that mode shall be repeated upon completion of the first chance ASM 5015 mode. The repeated mode shall be performed as described in this section except that the provisions of subdivision C 5 of this section shall be omitted.

3. If the vehicle failed only the ASM 5015 mode of the first chance test, then the first chance ASM 5015 mode shall not end at 90 seconds but shall continue for up to 180 seconds.

4. If the vehicle failed both ASM 5015 and ASM 2525 modes of the first chance test, then the vehicle shall receive a second-chance test for the ASM 2525 mode immediately following the first chance ASM 5015 mode. If the vehicle fails the second-chance ASM 2525 mode, then the vehicle shall fail the test, otherwise the vehicle shall also receive a second-chance ASM 5015 mode test.

Statutory Authority

§ 46.2-1180 of the Code of Virginia; § 182 of the Clean Air Act; 40 CFR Part 51, Subpart S.

Historical Notes

Derived from Volume 13, Issue 05, eff. January 24, 1997; amended, Virginia Register Volume 18, Issue 20, eff. October 1, 2002; Volume 29, Issue 24, eff. August 28, 2013; Volume 35, Issue 05, eff. November 28, 2018.

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