Diesel Data: Automotive Repair

Evaporative Emissions System: Description and Operation

Purge Control System Diagram:





PURGE CONTROL SYSTEM, NON-TURBOCHARGED VEHICLES

Purge Control System Diagram (Turbo):





PURGE CONTROL SYSTEM, TURBOCHARGED VEHICLES


CARBON CANISTER

While the engine is not running fuel vapors generated inside the fuel system are absorbed and stored in the carbon canister. When the engine is started once again the ECU will purge the fuel vapors from the carbon canister to the engine intake.

PURGE CONTROL SOLENOID VALVE

The purge control solenoid valve is an electrically operated valve controlled by the ECU that permits purging of the carbon canister. The ECU will operate the purge control solenoid valve only when engine speed exceeds 3000 rpm and coolant temperature exceeds 70 degrees C or 158 degrees F.

PURGE CONTROL VALVE (TURBOCHARGED VEHICLES ONLY)

The purge control valve is a vacuum operated valve that allows vacuum to scavenge the carbon canister. Vacuum signal to the purge control valve is controlled by the purge control solenoid valve.