Exhaust Gas Recirculation: Testing and Inspection

EGR System Testing:

SOLENOID TEST
Bring the engine to normal operating temperature. Operate at idle speed. Test the EGR solenoid as follows:
^ Check vacuum at solenoid vacuum source hose. Disconnect the line and attach a vacuum gauge to it.
^ Vacuum should be a minimum of 15 inches.
^ If vacuum is low, check the lines for kinks, twists, or a loose connection at vacuum connector on intake manifold.
^ If vacuum is OK, remove gauge, reconnect the line and proceed to next step.
^ Check vacuum at solenoid output port.
^ Disconnect the line and attach a vacuum gauge to output port. Vacuum reading should be zero (no vacuum) at this side of solenoid.
^ If vacuum reading is zero, leave the gauge connected and proceed to next step. If vacuum is present, check solenoid/ECU operation and repair as necessary.
^ Disconnect electrical connector at solenoid and note vacuum at solenoid output port. Vacuum should now be present at output port.
^ If vacuum is present, proceed to EGR valve test. If vacuum is not present, replace the solenoid.





EGR VALVE TEST
^ Leave the solenoid electrical connector disconnected. Bypass the vacuum transducer and connect the EGR valve solenoid output hose directly to the nipple on the EGR valve and note engine idle.
^ The engine should idle roughly or stall. If this occurs, the valve is OK. Proceed to Vacuum Transducer Test. If the idle does not change, proceed to next step.
^ Disconnect hose from EGR valve and connect a hand pump to EGR valve nipple.
^ Apply a minimum of 12 inches vacuum to the valve and note engine idle. If engine now idles roughly inspect vacuum lines between vacuum connector on intake manifold and EGR valve, and backpressure hose from EGR valve base to transducer for leaks.

EGR Transducer:

VACUUM TRANSDUCER TEST
^ Disconnect the transducer vacuum lines and backpressure line. Remove transducer.
^ Plug transducer output port.
^ Apply 1-2 pounds air pressure to transducer backpressure port. Air pressure can be supplied with a hand operated air pump or compressed air (regulated to correct psi).
^ Apply a minimum of 12 inches vacuum to input port.
^ Replace the transducer if it will not hold vacuum.