EGR Functional Tests

A faulty EGR system can cause ignition ping, rough idle, engine stalling, sags or hesitation, and/or lack of performance. It is important that this system be free from leaks. Any hoses that are cracked or leaking should be replaced.

Inspect all vacuum hoses and connections, and replace any that are cracked, hardened, or melted. Operation of the EGR system should be checked as follows:

1. Start engine and allow to reach normal operating temperature.
2. Allow engine to run at normal idle speed and set the parking brake.
3. Allow engine to idle in neutral, then quickly accelerate engine rpm to 2000 rpm.
4. Watch the stem of the EGR valve to see if there is movement. This movement can be seen by watching the groove on the valve stem.
5. Repeat the previous step several times to verify movement of the valve. Movement of the stem indicates that the control system is functioning properly, and the EGR gas flow test can now be performed.
6. If no movement of the valve stem is visible, refer to the DIAGNOSIS test procedure in this section.