Exhaust Gas Recirculation: Testing and Inspection

1. Check the vacuum hose for routing and installation.
2. Cold start and run the engine at idle.
3. Verify 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 in step 3 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. 63 PCV valve:

7. Connect a vacuum pump to the thermo valve and apply vacuum, Fig. 63. If it is not possible to establish a vacuum, the thermo valve is defective.
8. Remove the vacuum pump from the thermo valve and reconnect the green striped hose to the thermo valve.
9. Disconnect the green striped hose from the nipple of the carburetor and connect a vacuum pump to the green striped hose end.
10. While opening the sub EGR valve by pulling it by hand, apply 32 kPa (9.8 in. Hg) vacuum with a 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. Verify that the EGR port is not blocked. If not replace the EGR valve.
12. Remove the vacuum pump from the green striped hose end and reconnect the green striped hose to the carburetor.
13. Disconnect the yellow striped hose from the EGR control valve.
14. Connect a vacuum pump to the nipple of the EGR conrol valve.
15. While opening the sub EGR valve by pulling it by hand and apply 20 kPa (5.9 in. Hg) vacuum with a vacuum pump.
16. If the idling speed becomes unstable, the EGR valve is operating properly. If the idling speed remains unchanged, the valve is not operating. Verify that the EGR port is not blocked. If not replace the EGR valve.
17. Remove the vacuum pump from the EGR control valve and reconnect the yellow striped hose to the nipple of the EGR control valve.