Exhaust Gas Recirculation: Testing and Inspection

Fig. 31 Testing The EGR System:

EGR SYSTEM INSPECTION

1. Disconnect the vacuum hose (green stripe) from the mixing body and connect a hand vacuum pump to the vacuum hose.
2. While the engine is cold (coolant temperature less than 50 degrees C or 122 degrees F) allow engine to idle and apply vacuum. Verify that vacuum leaks.
3. Allow engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F) and apply 8 kPa or 2.3 in. Hg of vacuum while the engine is idling. Verify that vacuum holds. Increase vacuum to 23 kPa or 6.7 in. Hg and verify that vacuum holds and that engine idle becomes unstable.

Fig. 32 Testing The EGR Valve:

EGR VALVE INSPECTION

1. Remove the EGR valve from the vehicle and check for sticking, carbon deposits, or obvious damage. If necessary clean the valve with a suitable solvent.
2. Connect a hand vacuum pump to one nipple of the EGR valve and plug the other nipple. Apply 67 kPa or 19.4 in. Hg of vacuum and verify that the diaphragm chamber is leak tight.
3. Apply 8 kPa or 2.3 in. Hg of vacuum and verify that air will not pass through the valve.
4. Increase vacuum to 23 kPa or 6.7 in. Hg and verify that air will pass through the valve.
5. Re-install the EGR valve and torque to 7 to 11 Nm or 5 to 8 ft. lbs.

Fig. 34 Testing Operation Of The EGR Control Solenoid Valve:

EGR SOLENOID VALVE INSPECTION

1. Mark and then disconnect the vacuum hoses (blue stripe and red stripe) to the solenoid valve.
2. Disconnect the harness connector.
3. Connect a hand vacuum pump to the nipple the red striped hose was removed from.

figure ea117405-034

4. Apply vacuum and verify that when 12 vdc is applied to the solenoid that vacuum leaks.
5. Remove power from the solenoid and verify that vacuum holds.

figure ea117405-035

6. Measure coil resistance and verify that it is between 36 and 44 ohms at 20 degrees C or 68 degrees F.