Emission Control Systems: Description and Operation

The emission control system is used to reduce harmful gases (CO,HC and NOx), produced by the internal combustion engine. The emission control system has the following three major sub-systems:

1. CRANKCASE EMISSION CONTROL SYSTEM

The crankcase emission control system is a closed-type crankcase ventilation system that prevents blow-by gasses from escaping into the atmosphere. The blow-by gasses in the crankcase are routed back to the intake manifold for combustion.

2. EVAPORATIVE CONTROL SYSTEM

The evaporative control system prevents the escape of fuel vapors from the fuel tank and carburetor into the atmosphere. It consists of various components which collect, filter and route the fuel vapors to the intake manifold for combustion.

3. EXHAUST EMISSION CONTROL SYSTEM

The exhaust emission control system consists of a catalytic converter, exhaust gas recirculation and air-injection or pulsair system.


One or more of the following emission control systems are used depending on the country, state, model and engine. (The specific emission control systems used on your vehicle are listed under SYSTEM I.D.).


AIR INJECTION (AI)
AIR SUCTION (AS)
DASH POT (DP)
EVAPORATIVE EMISSION CONTROL (EVAP)
EXHAUST GAS RECIRCULATION (EGR)
FUELPIPE RESTRICTOR (FR)
HIGH ALTITUDE COMPENSATION (HAC)
MIXTURE CONTROL (MC)
OXIDATION CATALYST (OC)
POSITIVE CRANKCASE VENTILATION (PCV)
THREE-WAY CATALYST (TWC)