Exhaust Gas Recirculation: Testing and Inspection

EGR System Testing:

EGR VALVE TESTING

1. Warm engine to operating temperature.
2. Place finger on valve diaphragm and rev engine; diaphragm should move.
3. Disconnect vacuum hose from valve and attach hand vacuum pump.
4. Apply 10 inHg vacuum. Diaphragm should move and engine may idle rough or stall.
5. Taking precautions for hot components, grasp top of EGR valve and check for looseness by trying to rotate valve in both directions. There should be no looseness.
6. Replace the EGR valve if it fails any of these tests.

EGR MODULATOR (TRANSDUCER) TESTING

1. Remove vacuum hoses (3) from modulator.
2. Place finger over port "P" and blow into port "Q." Air should pass through filter part of modulator.
3. Blow air into port "R" and repeat the above test. Check that there is a strong resistance to air flow.
4. Replace modulator if it fails this test.

VACUUM SWITCHING VALVE (EGR CONTROL SOLENOID) TESTING

1. Disconnect vacuum hoses (2) from vacuum switching valve (VSV).
2. Disconnect electrical connector with ignition "OFF."
3. Check resistance between VSV electrical terminals. It should be 33-39 ohms.
4. Blow into port "A." Air should flow through filter, not port "B."
5. Reconnect electrical connector, turn ignition "ON" and ground diagnostic terminal (refer to ON-BOARD DIAGNOSTICS).
6. Blow into port "A" and air should now flow out port "B."
7. Replace VSV if it fails these tests.