EGR Function Testing Geo Storm I

ALL MODELS EXCEPT 1989-93 LEMANS (PORTED EGR VALVE)

1. Ensure engine is at normal operating temperature. Disconnect vacuum hose at EGR valve. Connect a vacuum pump to EGR valve. Start engine.
2. Apply vacuum to EGR valve. If engine runs rough or stalls, and gauge holds vacuum, EGR valve is functioning properly. Connect a vacuum gauge to EGR hose. Increase engine speed to about 3000 RPM. If vacuum is shown on gauge, system is functioning properly.

1988-93 LEMANS (POSITIVE BACKPRESSURE EGR VALVE)

1. Firmly grasp top of EGR valve and check for looseness by trying to rotate valve in both directions. If looseness is felt, EGR valve is defective. Ensure engine is at normal operating temperature.
2. With engine idling, push up on underside of EGR diaphragm. If idle speed drops, EGR valve is functioning properly. Observe EGR valve diaphragm and increase engine speed to 2000 RPM. If EGR valve diaphragm moves, EGR system is functioning properly.