Mark VII V8-302 5.0L HO (1986)
EGR Valve: Testing and Inspection
Valve and Transducer Assembly
1. Make certain that all vacuum hoses are correctly routed and securely attached. Replace cracked, crimped or broken hoses.
2. Make certain there is no vacuum to the EGR valve at idle with the engine at normal operating temperature.
3. Install a tachometer.
4. Plug the tailpipe(s) to increase the exhaust system backpressure, leaving a 1/2-inch diameter opening to allow exhaust gases to escape.
5. Remove the vacuum supply hose from the exhaust backpressure transducer nipple and plug the hose. Do not disconnect the transducer from the EGR
valve.
6. Start engine idle with transmission in NEUTRAL, and observe the engine idle speed. If necessary, adjust idle speed to the emission decal
specification.
7. Slowly apply 5-10 inches of mercury vacuum to the Backpressure Transducer vacuum nipple using a hand vacuum pump.
8. When vacuum is applied to the Backpressure Transducer and any of the following occur, replace the valve:
^ Engine does not stall.
^ Idle speed does not drop more than 100 rpm.
^ Idle speed does not return to normal (±25 rpm) after the vacuum is removed.
9. Unplug and reconnect the vacuum .supply hose to the exhaust backpressure transducer.
10. Remove the tailpipe plug(s).
11. The EGR system is OK.
