Emission Control Systems: Description and Operation

This vehicle uses the following emission control systems: Evaporative emission control system; Positive crankcase ventilation system; three-way converter; and computerized electronic fuel injection.

EVAPORATIVE EMISSION CONTROL SYSTEM (EVAP)
The evaporative emission control system stores fuel vapor generated in the fuel tank in the canister when the engine is not running. The fuel vapor is stored in the canister until it is drawn into the dynamic chamber and burned when the engine is started.

POSITIVE CRANKCASE VENTILATION SYSTEM (PCV)
The PCV valve is operated by intake manifold vacuum. When the engine is running at idle, the PCV valve is opened slightly and a small amount of blow-by gas is drawn into the engine. At higher engine speeds, the PCV valve is further opened and a larger amount of blow-by gas is drawn into the engine.

THREE WAY CATALYTIC CONVERTER (TWC)
The catalytic converter is used to convert the harmfull polutants CO, HC, and NOx into carbon dioxide, water vapor, and nitrogen gas respectively. To accomplish this, platinum, palladium, and rhodium are used as catalysts to convert these harmful pollutants into non-poisonous compounds.

COMPUTERIZED ELECTRONIC FUEL INJECTION
The fuel injection system consists of a computer and various engine sensors, including an exhaust gas oxygen sensor. The computer monitors engine operating conditions and controls output devices that regulate fuel injection, ignition timing and certain emission control devices. The system maintains the air/fuel ratio very close to the ideal ratio for all engine speeds and loads. This improves driveability and increases efficiency of emission control devices such as the catalytic converter for reduced emissions.