Canister Purge Solenoid: Description and Operation

FUNCTION

The Duty Cycle EVAP Purge solenoid controls the rate of vapor flow from charcoal canister to the throttle body. The PCM regulates purge solenoid operation.

OPERATION

The PCM controls purge solenoid by switching the ground path on and off based on engine operating conditions. When solenoid is energized, vacuum is prevented from reaching the charcoal canister. When solenoid is de-energized, vacuum is allowed to reach the charcoal canister. The PCM energizes and de-energizes the solenoid 5 to 10 times per second. The PCM controls the rater of flow by adjusting solenoid pulse width.

CONDITIONS

The PCM will not allow vapors to be purged until the engine has reached a predetermined temperature and a time delay interval has elapsed. The PCM, under certain idle conditions, energizes the solenoid to update fuel calibration.