System Operational Test

The following procedures will allow a basic operational test of the EGR system. Since the EGR operation is controlled by the ECM, refer to COMPUTERIZED ENGINE CONTROLS for further information concerning testing of the systems operation.

EGR System Inspection:

1. Disconnect the green striped vacuum hose from the EGR valve and connect a hand vacuum pump using a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 20 degrees C or 68 degrees F) race the engine suddenly and verify that no vacuum is present.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F) and race the engine. Verify that vacuum momentarily rises to 150 mm Hg or 5.9 in. Hg or more.

EGR Valve Inspection:

4. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
5. Using the vacuum pump apply 215 mm Hg or 8.5 in. Hg of vacuum while the engine is at idle and verify that idle becomes unstable.