Exhaust Gas Recirculation: Testing and Inspection

GASOLINE ENGINES

ENGINE IDLES ABNORMALLY ROUGH AND/OR ENGINE STALLS

1. The EGR valve vacuum hoses could be incorrectly routed. Check EGR valve vacuum hose routing and correct as required.
2. A leaking or damaged EGR valve could cause this problem. Check EGR valve for correct operation.
3. EGR valve gasket is damaged or EGR valve mounting bolts are loose. Check EGR mounting bolts, tighten as required. If bolts are not loose, remove EGR valve and check gasket. Replace gasket as required.
4. Faulty EGR-TVS. Check vacuum into valve from carburetor EGR port with engine at normal operating temperature. If no vacuum, replace EGR-TV.
5. Incorrect vacuum to EGR valve at idle. Check vacuum from carburetor EGR port with engine at normal operating temperature. Connect vacuum gauge to EGR valve hose. If vacuum is more than 1.0 inch Hg., replace EGR valve.

ENGINE STALLS ON DECELERATION

1. EGR control valve blocked. Check internal control valve for proper operation, replace as required.
2. Plugged EGR vacuum hose. Check EGR valve vacuum hose for kinks or excessive bends. Remove and replace vacuum hose as required.
3. Sticky or binding EGR valve. Remove and replace EGR valve as required.

ENGINE RUNS ROUGH ON LIGHT THROTTLE ACCELERATION

1. The EGR valve vacuum hoses could be incorrectly routed. Check EGR valve vacuum hose routing. Correct as required.
2. Loose EGR valve. Tighten EGR mounting bolts.
3. Sticky or binding EGR valve. Remove and check EGR valve. Replace as required.
4. Damaged or no EGR gasket. Check and correct as required.

PART THROTTLE ENGINE DETONATION

1. EGR control valve blocked. Check internal control valve for proper operation. Replace as required.
2. insufficient exhaust gas recirculation flow during part throttle acceleration. Check EGR valve vacuum hose routing. Correct as required. Check EGR valve operation. Remove and replace as required.
3. EGR control valve blocked. Check EGR valve vacuum hose routing. Correct as required.

ENGINE STARTS BUT STALLS WHEN COLD

1. EGR valve vacuum hoses incorrectly routed. Check hose routing and correct as required.
2. EGR-TVS malfunctioning when engine is cold. Check EGR control valve or EGR-TVS to ensure they are operating properly. Replace as required.