Usage:
3406B (7FB, 8TC, 4MG, 5YG, 3ZJ, 5KJ, 2EK) Truck Engines
Stepped up enforcement of two laws aimed at improving air quality in the State of California may soon result in citations issued to owners of vehicles emitting excessive black smoke while operating within state boundaries. All heavy-duty diesel powered trucks, regardless of their state registration, will be subject to these enforcement practices.
California Air Resources Board (CARB) Snap Idle Test
In 1988, California enacted Senate Bill SB 1997 creating Section 44011.6 in the California Health and Safety Code. This section authorizes CARB, in conjunction with the California Highway Patrol (CHP), to issue citations to owners or operators of vehicles that emit excessive smoke or have emission control system components that have been tampered with or are malfunctioning.
Owners of cited vehicles are required to have them repaired immediately and to pay a civil penalty of $800 for the first violation. If repair is made within 45 days, $500 will be refunded. The penalty for second and subsequent violations within 12 months is $1800. There is no refund for the second or subsequent violation, and subsequent violators must submit to a mandatory post-repair test. CARB has authority to fine up to $1500 per day for each day the vehicle is in violation, and subsequent violators with outstanding unpaid citations may be subject to vehicle impoundment.
The method used to determine compliance with Health and Safety Code Section 44011.6 is a no-load "snap idle" test with exhaust smoke measured in percent opacity using a light extinction type smoke meter. The smoke meter most commonly used is a Wager Model 650A.
The CARB Snap Idle test is simple to perform. With the vehicle stationary, and the engine at normal operating temperature at low idle, the engine is accelerated rapidly to high idle speed three times to "clear out the stacks". Then, with the smoke meter in place, the procedure is repeated. The average of the two closest peak opacity readings is the smoke number used for comparison to the smoke standard.
Before the test is performed, it is very important to make sure the Fuel Ratio Control (FRC) is "cocked" or activated. Most FRC's require both oil pressure and boost to cock. If the snap idle test is performed in the field by a CARB inspection team, the engine should be kept running to avoid deactivating the FRC. If the engine is shut down, operate the engine to develop 5-10 psi boost before a smoke test is performed.
The current smoke standard is 55% for pre-1991 model year heavy-duty diesel vehicles, and 40% for 1991 and newer vehicles. The proposed standard is 40% for all 1974 and newer model year heavy-duty diesel vehicles unless an exemption is obtained. Vehicles exempt from the 40% standard, must still meet the 55% standard.
Air Quality Management Districts (AQMD) Lug Test
The AQMD have initiated a separate program authorized under California Vehicle Code, 42001.2 to regulate smoke emissions. While centralized in the South Coast Air Basin region, program enforcement can be conducted by state and local law enforcement agencies statewide. Assembly Bill AB 911 approved July 18, 1990, amended Section 42001.2 of the California Vehicle Code to increase fines for violation of Section 27153.5.
Fines prescribed under this legislation for vehicle gross weights greater than 6001 pounds, increase to not less than $250 nor more than $2500 for the first offense, and not less than $500 nor more than $5000 for a second or subsequent offense within one year.
Compliance with Section 27153.5 will be determined under a loaded or "engine lug" condition during vehicle operation. Law enforcement officers, trained in the use of the Ringlemann Chart, will likely position themselves near a highway grade to observe smoke emissions from trucks climbing the grade. Smoke levels as dark or darker in shade as that designated as No. 1 on the Ringelmann Chart for a period of more than 10 seconds will be considered a violation subject to fine. Refer to Society Of Automotive Engines (SAE) Handbook, J255A, "Diesel Engine Smoke Measurement," information report for an explanation of the Ringelmenn Chart.
A simulated AQMD test can be performed on a chassis dynamometer. Observed smoke while the vehicle is being lugged down to peak torque engine speed (approximately 1200 rpm), can be compared to a Ringlemann Chart or measured with a smoke meter. No. 1 on the Ringlemann Chart corresponds to approximately 20% smoke opacity.
For engines emitting marginal smoke close to the 20% opacity limit, compliance with Section 27153.5 can be somewhat driver controllable. Generally, smoke increases as engine speed approaches peak torque. Avoiding a deep lug of extended duration may reduce visible smoke in hilly terrain.
Caterpillar Inc. truck engines are certified by the United States Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) to comply with smoke and gaseous emission standards prescribed by law at the time of manufacture.
Efficiency of emission control and engine performance depends on adherence to proper operation and maintenance recommendations, and use of recommended fuels and oils. Regular maintenance intervals are necessary to keep exhaust emissions within acceptable limits for the useful life of the engine. Refer to the Maintenance Section of the Operation and Maintenance Manual for further details.
If exhaust smoke is considered excessive, refer to the Truck Engine Service Manual for possible causes. For troubleshooting excessive black smoke, refer to the Exhaust Smoke Evaluation Form SEHS9366, and other published information.