Exhaust Gas Recirculation: Testing and Inspection

Fig. 69 Testing the EGR system.:

1. Disconnect the vacuum hose (green stripe) from the throttle body and connect a manual vacuum pump to the vacuum hose, Fig. 69.
2. While the engine is cold (coolant temperature less than 50 degrees C or 122 degrees F) verify that while the engine is idling, vacuum leaks from the thermo valve.
3. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F) and verify that while the engine is idling 6 kPa (2 in. Hg) of vacuum can be applied and held without affecting engine idle.
4. Apply 23 kPa (7 in. Hg) of vacuum and verify that engine idle becomes slightly unstable.