Exhaust Gas Recirculation: Testing and Inspection

1. Check the vacuum hose for routing and installation.
2. Cold start and run the engine at idle speed.
3. Check to ensure that increasing engine rpm (idle to 2,500 rpm) does not cause the EGR valve to operate. If the EGR valve operates, replace the thermo valve.
4. Warm up the engine until coolant temperature exceeds 85 degrees C or 185 degrees F.
5. Verify that when engine rpm is increased as described in step 3 that the EGR valve operates. If it does not operate, inspect the EGR control valve or the thermo valve.
6. Disconnect the green striped hose from the thermo valve.

Fig. 110 Testing EGR valve:

7. Connect a vacuum pump to the thermo valve and apply vacuum, Fig. 110. If it is not possible to establish a vacuum, the thermo valve is defective.
8. Remove the vacuum pump from thermo valve and reconnect the green striped hose to the thermo valve.
9. Disconnect the green striped hose from the nipple of the EGR control valve and connect a vacuum pump to the nipple.
10. Apply 32 kPa (10 in. Hg) vacuum with the vacuum pump.
11. If the idling speed becomes unstable the EGR valve is operating properly. If the idling speed remains unchanged, the valve is not operating. Replace the EGR valve.
12. Disconnect the vacuum pump from the nipple of the EGR control valve and reconnect the green stripe hose to the EGR control valve.