System Operational Test

Note: 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 Vacuum Delivery Test:

1. Disconnect the green striped vacuum hose from the EGR valve and connect a hand vacuum pump through a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 20 degrees C or 68 degrees F) race the engine and verify that vacuum is not present.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F).
4. Race the engine and verify that vacuum increases to 100 mm Hg or 3.9 in. Hg or more.

EGR Valve Inspection:

5. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
6. 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.