Emission Control Systems: Description and Operation

The emission control systems are used to reduce harmful gases (CO, HC, and NOx) in accordance with federal and state regulations.
The emission control system has the following four major systems:

CRANKCASE EMISSION CONTROL SYSTEM.
The crankcase emission control system prevents blow-by gases from escaping into the atmosphere. The blow-by gases in the crankcase are routed, through various components, back into the intake manifold for combustion.

COMPUTERIZED ENGINE CONTROL SYSTEM.
The computerized engine control system is made up of an ELECTRONIC CONTROL MODULE (ECM), various sensors and output devices. This system controls engine operation (i.e. A/F mixture, idle speed and ignition timing) to reduce pollutants while maintaining optimum driveability conditions and reducing fuel consumption.

EVAPORATIVE EMISSION CONTROL SYSTEM.
The evaporative control system prevents the escape of fuel vapors from the fuel tank and fuel system into the atmosphere. It consists of various components, which collect and lead the fuel vapors to the intake manifold for combustion.

EXHAUST EMISSION CONTROL SYSTEM.
The exhaust emission control system can (depending on model and engine) consist of three-way catalytic converters and an exhaust gas recirculation valve to reduce exhaust emission levels. Certain models are also equipped with an air injection system.