Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. Use this test to diagnose Positive Crankcase Ventilation (PCV) valve and related vacuum hoses.

1. Check For Stuck PCV Valve
   
   Ensure PCV valve maintenance schedule has been followed. Ensure proper PCV valve is installed. Remove PCV valve. Shake valve and listen for rattle. If PCV valve rattles when shaken, install PCV valve and go to next step. Replace PCV valve if it does not rattle when shaken. Verify repair.
2. Check PCV System
   
   Start engine and warm to normal operating temperature. Disconnect fresh air hose from remote air cleaner or outlet tube connecting MAF sensor-to-throtte body. Place a stiff piece of paper over end of hose. If vacuum from hose does not hold paper in place for one minute, go to next step. If vacuum from hose holds paper in place for one minute, PCV system is okay. If directed here to diagnose a symptom, return to appropriate symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES article to complete testing.
3. Check Evaporative Emission System
   
   Disconnect evaporative emission hose from PCV system and plug connector. Again, place a stiff piece of paper over end of hose. If vacuum from hose does not hold paper in place for one minute, isolate vacuum leak or restriction in PCV system and repair as necessary. If vacuum from hose holds paper in place for one minute, PCV system is working properly at this time. Go to SYSTEM TESTS (EVAPORATIVE EMISSIONS)  to diagnose EVAP system vacuum leak.