Evaporative Emissions System: Description and Operation

Description
The evaporative emission control system consists of fuel separator, the two-way check valve, the charcoal canister, the purge solenoid valve, the powertrain control module (PCM), and the input devices. The amount of evaporative fumes introduced into the engine and burned is controlled by the purge control solenoid valve to correspond the engine's operating conditions. The maintain best engine performance, the purge control solenoid valve is controlled by the PCM.

Operation
The purge solenoid valve is controlled by duty signals from the PCM to perform purging of the charcoal canister. Purging is done when these conditions are met:
1. After warm-up
2. Driving in gear
3. Accelerator pedal depressed (idle switch OFF)
4. Oxygen (O2)sensor functioning normally