Exhaust Gas Recirculation: Testing and Inspection

Checking EGR Valve:

SYSTEM INSPECTION

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

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

WARNING: Be careful when checking the EGR control valve be cause the surrounding area is very hot.

4. Accelerate the engine and check that the diaphragm of the EGR control valve moves upward.

SOLENOID VALVE (EGR)

1. Disconnect the vacuum hose from the solenoid valve and vacuum pipe.

Solenoid Switching Valve:

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

EGR MODULATOR VALVE

1. Remove the EGR modulator valve.

Checking EGR Modulator Valve:

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


EGR CONTROL VALVE

Checking EGR Valve:

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

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

3. Warm up the engine and run it at idle.

Checking EGR System:

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

EGR Position Sensor Connector Identification:

EGR POSITION SENSOR RESISTANCE INSPECTION (California only)
1. Disconnect the EGR position sensor connector.
2. Check resistance between the terminals as shown.

Terminals Resistance

A-B 5 kohms
A-C 0.7-5 kohms
B-C 0.7-5 kohms

EGR CONTROL VALVE

Checking EGR Valve:

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

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