Exhaust Gas Recirculation: Testing and Inspection

EGR System Testing:

EGR SOLENOID TEST
1. Bring the engine to normal operating temperature. Operate at idle speed.
2. Disconnect the hose at the solenoid vacuum source port and attach a vacuum gauge to it.
3. Vacuum should be a minimum of 15 inches Hg.
- If vacuum is low, check the line for kinks, twists, or a loose connection at the vacuum connector on the intake manifold.
- If vacuum is OK, remove gauge, reconnect the line and proceed to next step.
4. Check vacuum at solenoid output port.
5. Disconnect the line and connect 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, proceed to EGR SOLENOID CLICK TEST.
6. 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:

EGR SOLENOID CLICK TEST
1. Unplug solenoid electrical connector.
2. Connect a 12 volt source to one of the solenoid terminals.
3. Connect and disconnect a ground to the other solenoid terminal.
- If the solenoid clicks each time the ground is provided, the solenoid is operating properly.
- If the solenoid does not click when the ground is provided, the solenoid is not operating correctly and should be replaced.

EGR Valve:

EGR VALVE TEST
1. 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 idle does not change, proceed to next step.
2. Disconnect hose from EGR valve and connect a hand vacuum pump to EGR valve nipple.
3. Apply a minimum of 12 inches vacuum to the valve and note engine idle. If the engine idles roughly, inspect vacuum lines between vacuum connector on intake manifold and EGR valve, and back-pressure hose from EGR valve base to transducer for leaks.
- If no leaks are found proceed to VACUUM TRANSDUCER TEST.
- If the idle did not change, remove the EGR valve and inspect the valve and the exhaust passage in the manifold for blockage, repair as necessary. If no blockage is present replace the EGR valve.

Transducer Testing:

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