Exhaust Gas Recirculation: Testing and Inspection

Fig. 17 Connect Vacuum Guage:

Fig. 18 Vacuum Reading With Manifold Vacuum Applyed To Port R:

1. Start engine and ensure engine runs properly at idle. If engine runs rough or stalls, check for improperly seated EGR valve.
2. With coolant temperature below 86°F,install a vacuum guage and run engine 3500 RPM and observe vacuum gauge, Fig. 17. If gauge reading is not zero, BVSV is defective.
3. Warm engine to normal operating temperature and observe gauge reading at 3500 RPM. Gauge should indicate low vacuum.
4. Disconnect vacuum hose from port R of vacuum modulator and connect manifold vacuum directly to port R. Vacuum gauge should indicate high vacuum at 3500 RPM, Fig. 18a
5. If improper readings are obtained in steps 3 and 4, check for defective vacuum modulator.
6. Remove vacuum gauge and adapter, reconnect proper vacuum hose to modulator, then apply manifold vacuum directly to EGR valve with engine idling.
7. If engine does not run rough or stall, EGR valve is defective.