Exhaust Gas Recirculation: Testing and Inspection

Fig. 175 E.G.R. VALVE TEST:

INITIAL TEST
- Check visually for leaks and good connection on the vacuum system.
- Inspect wiring and connectors.
- Apply 12 VDC to vacuum control valve. Proceed as follows:

EGR vacuum valve operates and engine runs rough:
Engine should run extremely rough, indicating a maximum amount of exhaust gas recirculation. In this case, the vacuum system is functioning correctly.

EGR vacuum valve does not operate and engine runs normally:
- Disconnect manifold vacuum hose from the EGR vacuum valve. Check end of hose for vacuum. If vacuum is not present, check hose and rubber end joints.
- Disconnect vacuum hose from EGR valve. Check the end of hose for vacuum. If vacuum is present, replace and test using a new EGR vacuum valve.
- If vacuum is not present, check hose and rubber end joints for leaks. If intact, replace valve and retest.


EGR vacuum valve operates but engine runs normally or slightly uneven:
Remove and clean EGR pipes and vacuum valve.