Exhaust Gas Recirculation: Testing and Inspection

SYSTEM INSPECTION

Checking EGR Valve:

NOTE: Check condition of wiring harness, vacuum lines, and connectors before checking sensors or switches.

1. Start engine.
2. Accelerate engine and verify that EGR valve diaphragm does not move while engine is still cold.
3. Warm up engine to operating temperature and run at idle.

WARNING: Use care when checking EGR valve; surrounding area is hot.

4. Accelerate engine and check that EGR diaphragm moves upward.

EGR SOLENOID VALVE

Solenoid Switching Valve:

1. Disconnect vacuum hose from valve and vacuum pipe.
2. Blow through valve from vacuum hose "A".
3. Check that air flows from port "B".
4. Disconnect valve connector.
5. Connect 12V and a ground to solenoid terminals.
6. Blow through valve from vacuum hose "A".
7. Check that air flows from valve air filter.

EGR MODULATOR VALVE

Checking EGR Modulator Valve:

1. Remove modulator valve.
2. Plug No. 1 port and connect vacuum pump to No. 3 port.
3. Blow into exhaust gas port. Operate vacuum pump and verify that vacuum is held.
4. Release exhaust gas port and confirm that vacuum is released.

EGR CONTROL VALVE

Checking EGR Valve:

1. Manually actuate valve by pushing on diaphragm with finger.
2. Check that spring resistance is present and diaphragm moves freely with no sticking or binding.

NOTE: Before replacing EGR valve, check intake air and control systems.

3. Warm up engine and run at idle.

Checking EGR System:

4. Connect vacuum pump to valve and apply vacuum.
5. Check that engine runs roughly or stalls at more than 1.6 - 2.4 inHg (40 - 60 mmHg).
6. If not correct, replace valve.

EGR POSITION SENSOR RESISTANCE INSPECTION (California only)

EGR Position Sensor Connector Identification:

1. Disconnect position sensor connector.
2. Check resistance between terminals as shown.

Terminals Resistance

A - B 5k ohms
A - C 0.7 - 5K ohms
B - C 0.7 - 5K ohms