Exhaust Gas Recirculation: Testing and Inspection

1. Check vacuum hose routing. If hose is improperly connected, clogged or leaking, repair or replace as necessary.
2. Run engine until normal operating temperature is reached and continue to run at idle.
3. Disconnect and plug hose from top of EGR control valve. If engine begins to run rough, check EGR control valve.
4. Connect suitable vacuum gage to EGR control valve and ensure gage indicates no vacuum.
5. Increase engine speed, then return to idle. Ensure vacuum gage indicates vacuum until engine speed returns to idle.
6. If vacuum is not as described, check duty solenoid valve and terminals 2L and 2K of emission control unit.
7. Using tee fitting, connect suitable vacuum gage between duty solenoid valve and EGR control valve.
8. Accelerate engine and note vacuum gage reading.
9. Disconnect vacuum hose from top of EGR control valve and plug hose, then accelerate engine and note vacuum gage reading.
10. If vacuum in step 9 is not greater than that in step 8, check EGR position sensor, 1F terminal of emission control unit and the duty solenoid valve.
11. On 1988 models, disconnect connectors from water temperature switch and connect them with a jumper wire.
12. On all models, ensure no vacuum is indicated when engine is accelerated. If vacuum is indicated, check duty solenoid valve and 1Q terminal of emission control unit.