Exhaust emissions are controlled by a combination of engine modifications and special component systems. Component usage varies according to model, engine and location of original purchase. All vehicles, except California, must meet the requirements of Light Duty Cycle Emission Standards.
California vehicles with a GVW of 8500 lbs. or less, must meet the requirements of Light Duty Cycle Emission Standards. California vehicles with a GVW of 8501 lbs. or more, must meet the requirements of Heavy Duty Cycle Emission Standards.
AIR INJECTION
The air injection system consists of air pump, air control valve, check valves, injection tubes and various air distribution lines. Injection of fresh air in exhaust manifold causes an afterburn which results in lower emission levels.
ELECTRONIC SPARK & FUEL CONTROL
All models have systems which electronically control the air/fuel ratio and ignition timing. These functions are controlled by the Single Module Engine Controller (SMEC). The system can adjust air/fuel mixture according to different modes of engine operation.
During closed loop operation, the computer continuously monitors and maintains air/fuel mixture close to the ideal ratio of 14.7:1. For additional information, see appropriate article in the COMPUTERIZED ENGINE CONTROLS section.
CATALYTIC CONVERTER
The catalytic converter causes a combustion-type reaction which further consumes unburned elements in engine exhaust. Catalytic converter is located in exhaust system ahead of muffler.
OTHER EMISSION SYSTEMS
For additional information on description, operation, testing and adjusting other exhaust emission systems, refer to the following articles in this section.