1974-93 All Models Except Diesel
- Disconnect vacuum hose to EGR valve. Using a hand-held vacuum pump, apply vacuum to EGR valve with engine at idle. Engine should run rough or stall. If engine does not run rough or stall, check EGR valve passages for blockage or faulty EGR valve. Clean passages as necessary. If passages are clear, replace EGR valve.
- Install vacuum gauge to ported vacuum port to EGR. Raise engine RPM. Vacuum should be present. If vacuum is not present, clear vacuum port of blockage.
Note. For systems equipped with a double or single diaphragm type EGR valve, perform the following tests
Double Diaphragm Valve
Ensure all vacuum hoses are routed properly. Warm engine to normal operating temperature. With engine at idle, switch hoses on EGR valve, carburetor should make bubbling noise. If bubbling noise is not heard, check other EGR system controls. See appropriate manual for troubleshooting.
Single Diaphragm Valve
- Check all vacuum hoses for correct routing. Warm engine to operating temperature. Disconnect vacuum hose from EGR valve.
- With engine at idle, apply intake manifold vacuum to EGR valve. On systems equipped with a modulator and/or auxiliary control valve, engine should run rough or carburetor should make bubbling noise.
- On systems not equipped with a modulator and/or auxiliary control valve, increase engine speed to 3000-3500 RPM. Carburetor should make bubbling noise. If bubbling noise is not heard, check other EGR system controls. See appropriate manual for troubleshooting.
TEST 2
For EGR function testing, see the following publication: IMPORTED CARS, LIGHT TRUCKS & VANS SERVICE & REPAIR manual or ENGINE PERFORMANCE IMPORTED CARS, LIGHT TRUCKS & VANS supplement.
1994
- Ensure EGR vacuum modulator filter is clean and in good condition. Clean filter with compressed air (if necessary).
- Using "T" connector, install vacuum gauge in vacuum line to EGR valve. Start engine. Ensure engine runs idles smoothly to ensure proper seating of EGR valve.
- Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of data link connector No. 1, located in engine compartment. NOTE: The EGR system components can be checked with engine coolant temperature less than minimum temperature and engine at specified engine RPM.
- Warm engine to normal operating temperature. Operate engine at 2500-3500 engine RPM again. Ensure a low vacuum reading is now obtained.
- Disconnect vacuum hose from port "R" of EGR vacuum modulator. (Scheme 3) Using additional hose, connect port "R" of EGR vacuum modulator directly to intake manifold. High vacuum reading should be obtained at 2500-3500 engine RPM. NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
- Remove vacuum hose and reconnect original vacuum hose to EGR vacuum modulator. To check EGR valve operation, remove vacuum hose from EGR valve.
- Using vacuum pump, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If EGR system does not operate as described, each individual component should be tested. Shut engine off. Remove jumper wire from data link connector No. 1.
Scheme 3
TEST 3
For EGR function testing, see appropriate ENGINE PERFORMANCE section of electronic information product.