EGR Control System Test

NOTE:
EGR system must pass CONTROL SYSTEM TEST and GAS FLOW TEST to pass FUNCTIONAL TEST.


SYMPTOMS

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.


VISUAL INSPECTION

1. Check condition and routing of vacuum hoses. Refer to Vehicle Emission Control Information (VECI) label, (underhood).
2. Ensure all vacuum hoses and electrical wires are clear of exhaust manifold to prevent deterioration. Due to temperature, vacuum hoses should always be a minimum of three inches from exhaust manifold.


FUNCTIONAL TEST

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.