Exhaust Gas Recirculation: Testing and Inspection
Non-California EGR System Test:
EGR SYSTEM TEST - NON-CALIFORNIA MODELS
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.
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.
Testing The EGR System Using A Vacuum Tee:
EGR SYSTEM TEST - CALIFORNIA MODELS
COLD ENGINE TEST - Coolant temperature is below 60°C (140°F)
1. Disconnect the green striped vacuum hose from the EGR Valve.
2. Using a three-way terminal and vacuum hose, connect a hand vacuum pump into the EGR valve line.
At this point, do not apply vacuum.
3. Quickly depress the accelerator pedal to race the engine.
No change in vacuum (atmospheric pressure) should be detected.
AFTER THE ENGINE IS WARM - Coolant temperature is above 70°C (158°F)
4. Again quickly depress the accelerator pedal to race the engine. Vacuum should rise temporarily to 3.9 in.Hg or more.
Testing EGR System & Valve:
5. Remove the three-way terminal and connect the vacuum pump directly to the EGR valve.
6. Check to see that the engine stalls or the idle is unstable when a vacuum of 6.8 in.Hg is applied to the EGR valve.
Refer to MAINTENANCE PROCEDURES for EGR SYSTEM 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.
EGR Control Solenoid Valve Test:
EGR CONTROL SOLENOID VALVE
NOTE: When disconnecting the vacuum hoses, mark or label them to ensure proper routing when reconnecting.
1. Disconnect the vacuum hoses from the solenoid valve.
2. Disconnect the harness connector.
3. Connect a hand vacuum pump to the nipple which the hose was connected to.
4. Connect jumper leads to the solenoid terminals.
EGR Control Solenoid Valve Voltage Test:
5. While applying vacuum to the solenoid, apply battery voltage directly to the terminals.
Vacuum should hold.
6. Discontinue voltage. Vacuum should leak.
7. Measure the resistance between the terminals of the solenoid valve. Refer to SPECIFICATIONS.
EGR VALVE INSPECTION
EGR 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.
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.