Evaporative Emissions (EVAP) Purge Valve

Evaporative Emissions (EVAP) Purge Valve

The ECM provides a PWM earth path to control the operation of the purge valve. When the ECM is in the open loop fuelling mode the purge valve is kept closed. When the vehicle is moving and in the closed loop fuelling mode the ECM opens the purge valve.

When the purge valve is open fuel vapor is drawn from the EVAP canister into the inlet manifold. The ECM detects the resultant enrichment of the AFR, from the inputs of the front HO2S, and compensates by reducing the duty cycle of the fuel injectors.