Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
This test is performed when directed here from one of the following symptoms in TROUBLE SHOOTING - NO CODES - CNG & GASOLINE article:
- Rough Or Rolling Idle, Stalls, Misses, Hesitation Or Surge
- Hard Start/Long Crank Or Erratic Start/Crank
- Slow Return To Idle
- Spark Knock
- Poor Fuel Economy
- High Oil Consumption
- Exhaust Smoke
Use this test to diagnose Positive Crankcase Ventilation (PCV) valve and related vacuum hoses.