EGR System Test

WARNING: Apply parking brake and/or wheels before performing EGR system test.

A failed or malfunctioning EGR system can cause engine spark knock, sags or hesitation, rough idle, and/or engine stalling. To ensure proper operation of the EGR system, all passages and moving parts must be free of deposits that could cause plugging or sticking. Ensure that the system hoses does not leak. Replace leaking components.

Inspect hose connections between throttle body, intake manifold, EGR solenoid and transducer and the EGR valve. Replace hardened, cracked, or melted hoses. Repair or replace faulty connectors.

Check the EGR control system and EGR valve with the engine fully warmed up and running (engine coolant temperature over 150°F):
- With the transmission in neutral and the throttle closed, allow the engine to idle for 70 seconds.
- Abruptly accelerate the engine to approximately 2,000 rpm, but not over 3,000 rpm.
- The EGR valve stem should move when accelerating the engine (the relative position of the groove on the EGR valve stem should change).

Repeat the test several times to confirm movement.
- If the EGR valve stem moves, the control system is operating normally.
- If the control system is not operating normally, refer to the EGR Diagnosis Chart to determine the cause.