Exhaust Gas Recirculation: Testing and Inspection

Non-California EGR System Test:

EGR SYSTEM TEST


COLD ENGINE TEST - Coolant temperature is below 50°C (122°F)

1. Disconnect the green striped vacuum hose from the throttle body and connect it to a hand vacuum pump.
2. Plug the nipple at the throttle body from which the hose was removed.
3. With the engine idling, try applying vacuum.
Vacuum should leak.

WARM ENGINE TEST - Coolant temperature is above 85°C (185°F)
1. Disconnect the green striped vacuum hose from the throttle body and connect it to a hand vacuum pump.
2. Plug the nipple at the throttle body from which the hose was removed.
3. With the engine idling, apply 2.0 in.Hg vacuum.
Vacuum should hold and engine RPM should not be affected .
4. Increase vacuum to 7.0 in.Hg.
Vacuum should hold but the engine RPM should change to slightly unstable.

Refer to MAINTENANCE PROCEDURES for EGR SYSTEM cleaning.

EGR CONTROL VALVE TEST


1. Remove the EGR valve and check it for sticking or carbon deposits.
If such condition exists, clean with solvent to ensure tight valve seat contact.

EGR Valve Test:

2. Connect a hand vacuum pump to the EGR vacuum nipple.
If there is more than one nipple, the second nipple will need to be plugged for this test.
3. Apply 19.0 in.Hg vacuum to the vacuum chamber of the EGR valve.
Vacuum should not leak from vacuum chamber.
4. Apply 2.0 in.Hg. of vacuum. Blow air in from one side of the valve.
Air should not pass through
5. Increase vacuum to 7.0 in.Hg, while blowing air through EGR passage.
Air should pass through.

Refer to MAINTENANCE PROCEDURES for EGR Control Valve cleaning.

EGR Temperature Sensor Test:

EGR TEMPERATURE SENSOR

1. Remove the EGR Temperature Sensor.
2. Place the sensor in 50°C (122°F) water.
3. Measure the resistance between the terminals. Refer to SPECIFICATIONS.
4. Increase the water's temperature to 100°C (212°F).
5. Measure the resistance between the terminals. Refer to SPECIFICATIONS.
If there is a significant deviation from the standard value, replace the EGR Temperature sensor.

Thermo Valve Test:

THERMO VALVE TESTING


1. Disconnect the vacuum hoses from the thermo valve, and connect a hand vacuum pump to a nipple of the thermo valve.
2. When the engine coolant temperature is below 50°C (122°F), vacuum applied to the valve should leak.
3. When the engine coolant temperature has reached 80°C (176°F) or more, the vacuum applied to the valve should hold.