Miscellaneous Component Or System Checks

WARNING: This page does not describe the selected car, but rather 30 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.

Check the following:

Check Mass Air Flow (MAF) sensor input to PCM. Go to TEST DC: MASS AIRFLOW SENSOR , step 25) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.
Check engine mechanical condition. Check compression, camshaft, valve train components, etc. and repair as necessary. Check engine oil quality. See appropriate article in ENGINES.
Check fuel delivery system. Go to TEST HB: NATURAL GAS FUEL DELIVERY SYSTEM , step 1) (Natural Gas models), or go to TEST HC: GASOLINE FUEL DELIVERY SYSTEM , step 1) (all others) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.
Check secondary ignition system. Go to TEST JB: SECONDARY IGNITION , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.
Check PCV system. For Aviator and Mustang 4.6L, go to TEST HG: PCV SYSTEM , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. For all others, go to TEST HG: PCV SYSTEM , step 4) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.
Visually inspect engine oil quality.