Exhaust Gas Recirculation: Testing and Inspection
Fig. 26 Testing EGR System:
EGR SYSTEM INSPECTION (FEDERAL VEHICLES)
1. Disconnect the vacuum hose (green stripe) from the throttle body and connect a vacuum pump to the free end of the hose.
2. While the engine is cold (coolant temperature less than 50 degrees C or 122 degrees F) apply vacuum at idle and note that vacuum leaks.
3. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F).
4. Apply 45 mm Hg or 1.7 in. Hg of vacuum while the engine is at idle and note that vacuum is held.
5. Apply 220 mm Hg or 8.7 in. Hg of vacuum while the engine is at idle and note that the idle becomes unstable.
Fig. 28 Testing EGR System (California):
EGR SYSTEM INSPECTION (CALIFORNIA VEHICLES)
1. Disconnect the vacuum hose (green stripe) from the EGR valve and connect a vacuum pump with a "T" fitting.
2. While the engine is cold (coolant temperature less than 20 degrees C or 68 degrees F) race the engine while observing the vacuum gauge of the vacuum pump and note that there is no vacuum.
3. Allow the engine to warm up and race the engine again. Note that vacuum temporarily rises to 100 mm Hg or 3.9 in. Hg.
Fig. 29 Testing EGR Valve (California):
4. Disconnect the "T" fitting and connect the vacuum pump directly to the EGR valve.
5. While the engine is at idle apply 155 mm Hg or 5.9 in. Hg to the EGR valve and note that the engine becomes unstable.
Fig. 30 Component Locations (EGR Hose Vacuum Nipple):
EGR VALVE CONTROL VACUUM INSPECTION
1. Warm up the engine until coolant temperature exceeds 85 degrees C or 185 degrees F. Disconnect the vacuum hose from the throttle body EGR vacuum nipple and connect a hand vacuum pump to the nipple.
Fig. 32 EGR System Vacuum vs Engine RPM:
2. Start the engine and verify that while the engine is raced the vacuum rises as engine speed increases. If there is no vacuum or it does not change with engine speed the port in the throttle body may be clogged.
EGR VALVE INSPECTION
1. Remove the EGR valve and check it for sticking, carbon deposits, etc. If necessary clean the EGR valve with a suitable solvent.
2. Connect a hand vacuum pump to the EGR valve.
3. Apply a vacuum of 500mm Hg or 19.6 in. Hg and verify that the diaphragm chamber is leak tight.
4. Apply 45 mm Hg or 1.7 in. Hg of vacuum to the valve and verify that air does not pass through the EGR valve.
5. Increase vacuum to 220 mm Hg or 8.7 in. Hg and verfy that air will pass through the EGR valve.
6. Re-install the EGR valve when testing is complete and tighten the mounting bolts to 10 - 15 Nm or 7.3 - ll ft. lbs.
Fig. 34 Testing The Thermo Valve (Federal Only):
THERMO VALVE INSPECTION (FEDERAL VEHICLES ONLY)
1. Disconnect the vacuum hoses from the thermo valve and connect a hand vacuum pump to the nipple of the thermo valve.
2. Apply vacuum and verify that when the engine is cold (coolant temperature less than 50 degrees C or 122 degrees F) vacuum leaks.
3. Allow the engine to warm up (coolant temperature greater than 80 degrees C or 176 degrees F), apply vacuum and verify that vacuum is held.
4. If it is necessary to remove the thermo valve do not apply a wrench to the resin part of the valve. Re-install the thermo valve using 3M locking sealant 4171. Torque the thermo valve to 20-40 Nm or 15 - 30 ft. lbs.
5. Reconnect the vacuum hoses.
Fig. 36 Testing The EGR Temperature Sensor:
EGR TEMPERATURE SENSOR INSPECTION (CALIFORNIA VEHICLES ONLY)
1. Remove the EGR temperature sensor from the vehicle.
2. Place the sensor in water.
3. Heat the water to 50 degrees C or 122 degrees F. Verify that the resistance of the sensor falls between 60 and 83k ohms.
4. Heat the water to 100 degrees C or 212 degrees F. Verify the the resistance of the sensor falls between 11 and 14k ohms.
5. When re-installing the temperature sensor tighten it to 10 - 12 Nm or 7.3 - 8.6 ft. lbs.
Fig. 37 Connecting A Vacuum Pump To The EGR Control Solenoid Valve:
EGR CONTROL SOLENOID VALVE INSPECTION (CALIFORNIA VEHICLES ONLY)
1. Mark and then disconnect the vacuum hoses (yellow and green stripe) from the solenoid valve.
2. Disconnnect the harness connector.
3. Connect a hand vacuum pump to the nipple the green striped hose was removed from.
Fig. 38 Testing Operation Of The EGR Control Solenoid Valve:
4. Apply vacuum to the valve and verify that when 12 vdc is applied to the solenoid the vacuum holds.
5. Remove 12 vdc from the solenoid and verify that vacuum leaks through the valve.
Fig. 39 Testing The EGR Control Solenoid Valve Coil Resistance:
6. Measure the resistance of the solenoid coil and verify that the resistance falls between 36 and 44 ohms at 20 degrees C or 68 degrees F.