Exhaust Gas Recirculation: Testing and Inspection

EGR SYSTEM CHECK (California Emissions Only)

EGR Modulator Filter:

1. Remove EGR vacuum modulator and filter. Inspect filter and clean if necessary.
2. Reinstall filter and cap.

EGR Valve Testing:

3. Using a three way connect, connect a vacuum gage to the hose between the EGR valve and the EGR modulator.
4. Check the seating of the EGR valve by starting the engine and making sure the engine idles normally. If idle is rough and no other problems exist, relace EGR valve as necessary.
5. Connect a jumper wire between Data Link Connector (DLC) terminals "TE1" and "E1".
6. Make sure that engine coolant temperature is below 117° F (47° C). Accelerate engine to 2500 rpm and make sure that vacuum gauge reads zero vacuum. If vacuum is present, see EGR SV valve test. Replace EGR SV valve as necessary.
7. Run engine until engine coolant temperature is above 127° F (53° C) and accelerate engine to 2500 rpm and make sure that vacuum gauge reads low vacuum. If no, or high vacuum is present, see EGR SV valve test and EGR modulator valve test. Replace EGR SV valve and/or modulator as necessary.
8. Remove vacuum gauge and return vacuum hose to their proper locations.

EGR Valve Test:

9. Apply vacuum directly to the EGR valve. With the engine idling remove the MAP sensor vacuum hose and connect it to the EGR valve. The engine should run rough or even stall. If the engine continues to run normally replace the EGR valve.
10. Reconnect vacuum hoses to their proper locations and remove jumper from the Data Link Connector.




EGR MODULATOR

1. Remove vacuum hoses from modulator.

Modulator Check:

2. Place finger over modulator tubes "P" and "R".
3. .Blow in tube "Q." Air should pass through filter part of modulator.
4. Start the engine and maintain engine speed at 2500 rpm. Repeat steps 1 through 3. There should be a strong resistance to air flow.
5. Reconnect vacuum hoses to their proper locations. If EGR modulator fails this test, replace modulator.




EGR SOLENOID VACUUM (SV) VALVE

1. Remove EGR SV from vehicle.

EGR SV Valve Testing:

^ Using an ohmmeter measure the resistance between EGR SV valve terminals. Resistance when cold should be 37-44 ohms.

EGR SV Valve Testing:

^ Using an ohmmeter measure the resistance between EGR SV valve body and each terminal. Replace the EGR SV valve if continuity is detected.

EGR SV Valve Testing:

2. Blow air through port "E" of the valve and make sure that air flows from port "E" through the valve and out of the filter. Replace valve if air does not pass through the valve.

EGR SV Valve Testing:

3. Using two fused jumpers, apply voltage across the terminals of the EGR SV. Blow air through port "E" of the valve and make sure that air does not flow from port "E" through the valve and out of the filter. Replace valve if air passes through the valve.
4. Reinstall EGR SV valve.