Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 26 other vehicles, including the 1999 Mercury Tracer, 1999 Mercury Sable, 1999 Mercury Mystique, 1999 Mercury Mountaineer, and 1999 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

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.

Check PCV Valve

Ensure proper PCV valve is installed. Remove PCV valve. Shake valve and listen for rattle. If PCV valve rattles when shaken, install PCM valve and go to next step. Replace PCV valve if it does not rattle when shaken.

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-throttle 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 and testing is complete.

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 and repair as necessary. If vacuum from hose holds paper in place for one minute, proceed as follows:
- On models equipped with Fuel Tank Pressure (FTP) sensor, go to TEST HX, step 47).
- On models not equipped with Fuel Tank Pressure (FTP) sensor, go to TEST HX, step 94.
NOTE: To determine if vehicle is equipped with a FTP sensor, see appropriate wiring diagram in WIRING DIAGRAMS article.