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Evaporative Emission Control System Description

The evaporative emission (EVAP) control system used is the charcoal canister storage method. This method transfers fuel vapour from the fuel tank to an activated carbon, charcoal, storage device, or canister, to hold the vapours when the vehicle is not operating. When the engine is running, the fuel vapour is purged from the carbon element by inlet airflow and consumed in the normal combustion process.

Petrol vapours from the fuel tank flow into the canister. These vapours are absorbed into the carbon. The canister is purged by the engine control module (ECM) when the engine has been running for a specified amount of time. Air is drawn into the canister and mixed with the vapour. This mixture is then drawn into the inlet manifold.

The ECM supplies a ground to energise the evaporative emission (EVAP) canister purge solenoid valve. This valve is pulse width modulated (PWM) or turned ON and OFF several times a second. The evaporative emission (EVAP) canister purge solenoid valve PWM duty cycle varies according to operating conditions determined by engine load, fuel trim, and inlet air temperature.

Poor idle, stalling, and poor driveability can be caused by the following conditions:

The Evaporative Emission (EVAP) canister is an emission control device containing activated charcoal granules. The EVAP emission canister is used to store fuel vapours from the fuel tank. Once certain conditions are met, the engine control module (ECM) activates the evaporative emission (EVAP) canister purge solenoid valve, allowing the fuel vapours to be drawn into the engine cylinders and burned.