EGR Valve
- Connect a tachometer to engine. Connect vacuum gauge between EGR valve and EGR vacuum port. With engine cold, start engine, and ensure vacuum gauge indicates no vacuum at idle.
- Warm engine to operating temperature. Ensure vacuum gauge indicates no vacuum at idle. Increase engine speed to 2000 RPM. Vacuum gauge should indicate more than 6 in. Hg. If vacuum is not as specified, go to step 4). If vacuum is as specified, go to next step.
- Disconnect and plug vacuum hose to EGR valve. Engine speed should increase. Stop engine, push diaphragm plate by hand and release it. Ensure diaphragm plate returns smoothly to original position.
- Check vacuum hoses and ports for restrictions or leaks. If EGR valve does not function as described in step 3), replace EGR valve.
Courtesy of GENERAL MOTORS CORP.