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 ECU, refer to COMPUTERS AND CONTROL SYSTEMS for further information concerning testing of the systems operation.

EGR System Inspection:

1. Disconnect the vacuum hose (green stripe) from the throttle body and connect a vacuum pump to the free end of the hose.
2. While the engine is cold (coolant temperature less than 122° F (50° C)) apply vacuum at idle and note that vacuum leaks.
3. Allow the engine to warm up (coolant temperature greater than 185° F (85° C)).
4. Apply 1.7 in. Hg (45 mm Hg) of vacuum while the engine is at idle and note that vacuum is held.
5. Apply 8.7 in. Hg (220 mm Hg) of vacuum while the engine is at idle and note that the idle becomes unstable.