EGR 3 - Check EGR System Function

^ Install a tachometer.

^ Disconnect the Idle Air Control (IAC) solenoid electrical connector.

^ Remove and plug the vacuum supply hose from the EGR valve nipple.

^ START engine, IDLE with transmission in NEUTRAL, and observe idle speed. If necessary, adjust idle speed.


NOTE: If the engine will not Idle with IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not exceed a typical Idle rpm.

^ Slowly apply 5-10 inches of vacuum to the EGR valve nipple using a hand vacuum pump.

^ Does Idle speed drop more than 100 rpm with vacuum applied and return to normal (± 25 rpm) after the vacuum Is removed?

YES -- The EGR valve is OK. Unplug and reconnect the EGR valve vacuum supply hose. Reconnect the IAC solenoid connector. Refer to Diagnosis By Symptom. SEE Powertrain Management / Testing and Inspection / Diagnostic Routines.

NO -- Inspect the EGR valve for blockage or contamination. Clean the valve using EGR valve cleaner. Inspect valve for vacuum leakage. Replace if necessary. If EGR valve is OK, inspect the EGR flow path in the intake manifold for blockage.