Exhaust Gas Recirculation: Testing and Inspection

Fig. 32 Connecting Vacuum Gauge:

Fig. 33 Testing EGR System:

1. Connect vacuum gauge in line with EGR valve vacuum hose using a suitable fitting. Fig. 32
2. Start engine and ensure engine runs properly at idle. If engine runs rough or stalls, check for improperly seated EGR valve.
3. With coolant temperature below 113°F, operate engine at 3000 RPM and observe vacuum gauge. If gauge reading is not zero, BVSV is defective.
4. Warm engine to normal operating temperature and observe gauge reading at 3000 RPM. Gauge should indicate low vacuum. If gauge reading is incorrect, check for defective modulator or BVSV.
5. Disconnect vacuum hose from port R of EGR vacuum modulator and apply intake manifold vacuum to the port. Vacuum gauge should indicate high vacuum at 3000 RPM. Fig. 33

Fig. 34 Testing EGR Valve:

6. Disconnect the vacuum gauge and reconnect all vacuum hoses.
7. Apply intake manifold vacuum to the EGR valve with the engine idling. Fig. 34
8. The engine should run very rough and may stall.
9. If a problem is found, test each system component.
10. Reconnect all vacuum hoses to their proper locations.