Evaporative Emissions Purge Solenoid

The Powertrain Control Module (PCM) controls the operation of the normally closed Purge Solenoid. During the cold start warm-up period and the hot start time delay the purge solenoid is not energized. When de-energized the solenoid is closed and no vapors are purged from the Charcoal Canister. The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. Once in closed loop the Purge Solenoid is controlled using a Pulse Width Modulated (PWM) control circuit. The normally closed Purge Solenoid will open and allow engine vacuum from the Intake Manifold to draw vapors from the Charcoal Canister into the Intake Manifold to be burned by the engine. The PCM varies the vapor flow rate by changing the duty cycle on the purge solenoid control circuit. The PCM adjusts the pulse width of the Purge Solenoid based on engine operating conditions.