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. Inspect all vacuum hoses and connections, and replace any cracked, hardened, or melted hoses.
2. Set the parking brake, START engine and allow to reach normal operating temperature at normal idle speed.
3. Allow engine to idle in neutral for 70 seconds, then quickly accelerate engine rpm to 2000 rpm.
4. Watch the stem of the EGR valve to see if there is movement by observing the groove on the valve stem.
5. Repeat the previous test several times to verify valve movement. Movement of the stem indicates that the control system is functioning properly.
6. If no movement of the valve stem is visible, diagnose and repair problem before proceeding to next test, (refer to DIAGNOSIS section below).