EMISSION CONTROL SYSTEM: The emission control system is designed to send excessive fuel, oil and exhaust vapors or gases to the combustion chambers where they can be burned and, therefore, prevent them from reaching the atmosphere. This is accomplished by the charcoal canister which controls the fuel vapors, the PCV valve, which regulates the oiling system or crank case vapors, and the EGR valve, which regulates the exhaust gases. In addition, on new vehicles, the control unit utilizes the sensory to monitor the amount of exhaust emissions leading the combustion chambers, and adjust accordingly the air fuel mixture entering the combustion chambers so that they will burn more efficiently. The catalytic converter neutralizes, or breaks down further, the exhaust gases that actually leave the exhaust manifold. The air pump, found on some cars, pumps air to the exhaust system which allows the engine to burn the air fuel mixture more efficiently. A faulty air pump usually makes a grinding noise but has no effect on engine performance.
