Firebird V8-305 5.0L (1982)
EGR Valve: Testing and Inspection
Ported Vacuum & Negative Back Pressure EGR Valves
1. Check vacuum hoses for correct routing and EGR valve signal tube orifice for obstructions.
2. Connect vacuum gauge between EGR valve and carburetor--a minimum of 5 inches Hg vacuum should be available with engine running at normal
operating temperature.
3. Depress valve diaphragm, then position finger over source tube. Release diaphragm.
4. Valve is good if diaphragm takes at least 20 seconds to move to closed position. If diaphragm closes in less than 20 seconds, replace EGR valve.
NOTE: On engines equipped with EGR thermal vacuum switch or solenoid, there should be no EGR valve movement below the calibration
temperature. If movement occurs, check TVS or solenoid for proper operation.
Positive Back Pressure EGR Valve
1. Check vacuum hoses for correct routing and EGR valve signal tube orifice for obstructions.
2. Remove EGR valve from vehicle, and apply a constant vacuum of 10 inches Hg to EGR valve signal tube while observing position of valve. If
valve is not closed, replace EGR valve.
3. With vacuum supply still applied, direct a low pressure stream of air into EGR valve exhaust inlet. Valve should open. If not, replace EGR valve.
