Exhaust Gas Recirculation (EGR) Systems

7. The EGR valve operates only at part-throttle mode; thereafter, it must remain closed at the cranking mode, the closed throttle mode, and the wide open throttle mode.

8. The EGR valve assembly (9F483) is not serviced as released. The EVP sensor (9G428) and EGR valve (9H473) are to be serviced separately.


DIAGNOSIS The diagnosis for this valve system is part of the EEC System diagnosis. Perform Diagnosis after doing the Valve Leakage Test below.

*VALVE CLEANING PROCEDURE: Clean inlet and outlet ports with wire brush or scraper. Do not use

sandblasting or gasoline or other solvents to clean the EGR valve be-

Valve Leakage Test cause they will damage the valve.

1. Connect vacuum tester to EGR valve.

2. Apply 16.89-20.26 kPa (5-6 inches Hg.) to the valve.

3. Trap vacuum and hold. Vacuum should not drop more than 3.38 kPa (1 inch Hg.) in 30 seconds.

4. If the conditions are not met in Steps 2 and 3, service or replace the valve, O-ring, or EVP as required.


NOTE: ALL EEC VEHICLES

1. Check circuitry per appropriate EEC engine diagnostic.

2. Mechanical function to be checked as follows:

A. Check all vacuum lines for proper routing and leaks or restrictions. Service as required.

B. Disconnect the vacuum hose at the EGR valve and connect a vacuum gauge to the hose.

C. Take the engine to 2000-2500 rpm and release the throttle, repeat 8-10 times and check for consistent response.

HOT ENGINE: Vacuum should rise above 51 kPa (15 in. Hg.) and return to zero when the throttle is released. If the vacuum does not go to greater than 5a kPa (15 in. Hg.), check the vacuum source and service as required. If the vacuum gauge does not return to zero or is inconsistent, the solenoids are worn or damaged and must be replaced.

COLD ENGINE: If vacuum rises above zero the solenoids are leaking and must be replaced.

D. If the solenoids are not worn or damaged or were replaced and the symptom still exists, go to the vehicle symptom and continue with the EGR diagnostic.