EGR System Function Test

NON-BACK PRESSURE TYPE EXHAUST GAS RECIRCULATION SYSTEMS

Controlled By Thermal Vacuum Valve

Fuel Injected Models
1. Perform the functional test with the engine idling at least 2 minutes at operating temperature.
2. Disconnect the exhaust gas recirculation vacuum supply hose from the throttle body vacuum port. Cap the throttle body vacuum port from which the vacuum hose was disconnected.
3. Connect a suitable hand held vacuum pump to the disconnected exhaust gas recirculation vacuum supply hose.
4. Apply 8 inches Hg. of vacuum to the exhaust gas recirculation valve. The engine idle should become rough or the engine may stall as the vacuum is applied. The exhaust gas recirculation valve should hold the applied vacuum.
5. Disconnect the hand held vacuum pump and cap from throttle body port.
6. Connect a suitable vacuum gauge to the throttle body exhaust gas recirculation vacuum supply port.
7. Abruptly apply and release the throttle and note the vacuum gauge reading. The vacuum gauge needle should respond to the throttle movement.

Controlled By Solenoid

MFI Models
1. Perform the functional test with the engine idling at least 2 minutes at operating temperature.
2. Disconnect exhaust gas recirculation vacuum supply hose from exhaust gas recirculation valve. Using a vacuum Tee fitting, connect a vacuum gauge between the hose and the exhaust gas recirculation valve.
3. Abruptly apply and release the throttle and note the vacuum gauge reading. The vacuum gauge should indicate 3.9 inches Hg. of vacuum or more.
4. Disconnect the vacuum gauge and Tee.
5. Connect a suitable hand held vacuum pump to the exhaust gas recirculation valve vacuum supply fitting. If exhaust gas recirculation valve has two vacuum supply fittings, cap the other fitting.
6. Apply 10 inches Hg. of vacuum to the exhaust gas recirculation valve. The engine idle should become rough or the engine may stall as the vacuum is applied. The exhaust gas recirculation valve should hold the applied vacuum.
7. Disconnect the hand held vacuum pump and connect the vacuum hose.

BACK PRESSURE EXHAUST GAS RECIRCULATION SYSTEMS

Fuel Injected Models
1. Perform the functional test with the engine idling at least 2 minutes at operating temperature.
2. Abruptly apply and release the throttle and observe exhaust gas recirculation valve stem for movement. Movement of the exhaust gas recirculation valve stem should be noted. The use of a mirror may be necessary to view the exhaust gas recirculation valve stem.
3. Connect a suitable hand held vacuum pump to the exhaust gas recirculation valve vacuum supply fitting.
4. Apply 8 inches Hg. of vacuum to the exhaust gas recirculation valve. The engine idle should become rough or the engine may stall as the vacuum is applied. The exhaust gas recirculation valve should hold the applied vacuum.
5. Disconnect the hand held vacuum pump and connect the vacuum hose.