Exhaust Gas Recirculation: Testing and Inspection

SYSTEM TEST

1. Check vacuum hoses for proper routing and correct as necessary.
2. Start engine and allow to idle.
3. With engine cold, increase engine speed to 2500 RPM and observe EGR control valve. If control valve operates, replace thermo valve.
4. Allow engine to reach normal operating temperature, then again accelerate engine and observe control valve. Control valve should operate. If not, check for defective control and/or thermo valve.
5. Disconnect green-striped hose from thermo valve, then apply vacuum to valve with suitable vacuum pump. If no vacuum is available, replace thermo valve.
6. Reconnect hose disconnected in previous step, then disconnect green-striped hose from carburetor nipple and attach vacuum pump to hose end.
7. Manually open sub-EGR control valve, then apply approximately 10 inches Hg vacuum to hose end. Engine should idle roughly. If not, replace EGR control valve.
8. Reconnect hose to carburetor nipple, then disconnect yellow-striped hose at EGR control valve.
9. Connect vacuum pump to control valve nipple, manually open sub-EGR control valve, then apply approximately 6 inches Hg vacuum to control valve. Engine should idle roughly. If not, replace control valve.
10. Reconnect hose disconnected in previous step.

SUB-EGR CONTROL VALVE

1. Ensure valve operates smoothly when operated manually.
2. If valve is difficult to move, remove valve and clean and/or oil as necessary.
3. Install valve, then repeat step 1.
4. If valve still does not operate smoothly, it should be replaced.