Emission Control

Both EGR and canister purge operation are regulated by the ECU. Regulation of these 2 systems is accomplished through the use of an electrically-operated vacuum solenoid.

Whenever the solenoid is energized by the ECU, it prevents vacuum action on the EGR valve and canister. The solenoid is energized by the ECU during engine warm-up, improving cold driveability. It is also energized during closed throttle (idle), wide open throttle and during rapid acceleration or deceleration.

In this way the EGR is prevented from operating until the engine reaches a predetermined temperature. The canister purge does not operate until the oxygen sensor warms up and becomes operational. This prevents an over-rich mixture until the oxygen sensor can compensate for the extra fuel vapor.