Symptom Checks

Check the following items:

• If vehicle failed an EVAP Leak Test or a Purge Flow Test only, check for damaged fuel filler cap. Visually check all EVAP lines/hoses for proper connections, damage or blockage. Check EVAP canister for damage. If no problems are indicated, go to CIRCUIT TEST HX, step 44) in appropriate article:

For Contour & Mystique 2.0L, see TESTS W/CODES - 2.0L .

For Contour & Mystique 2.5L, see TESTS W/CODES - 2.5L .

For Windstar, see TESTS W/CODES .

• Check the following Parameter Identification (PID) values: DPFEGR, ECT, IAC, LONGFT 1, LONGFT 2, VPWR and VREF. See appropriate article:

For Contour & Mystique 2.0L, see PIN VOLTAGE CHARTS .

For Contour & Mystique 2.5L, see PIN VOLTAGE CHARTS .

For Windstar 3.0L, see PIN VOLTAGE CHARTS .

For Windstar 3.8L, see PIN VOLTAGE CHARTS .

• Check engine emissions. If HC emissions are excessive, check fuel delivery system. See CIRCUIT TEST HC in appropriate article:

For Contour & Mystique 2.0L, see TESTS W/CODES - 2.0L .

For Contour & Mystique 2.5L, see TESTS W/CODES - 2.5L .

For Windstar, see TESTS W/CODES .

• If fuel delivery system is okay, check secondary ignition system. See CIRCUIT TEST JB in appropriate TESTS W/CODES article. If ignition system is okay, check PCV system. See CIRCUIT TEST HG in appropriate TESTS W/CODES article. If PCV system is okay, check engine compression. Check engine mechanical condition. Check intake manifold gasket, camshaft and valves.
• If NOx emissions are excessive, check engine mechanical condition (excessive cylinder carbon build-up). If engine mechanical condition is okay, on A/T vehicles, check transmission torque converter operation. On all vehicles, check cooling system. If cooling system is okay, check for causes for engine running lean (vacuum leaks, low fuel pressure, etc.). If no problems are found, check catalytic converter efficiency. See appropriate article:

For Contour & Mystique, see SYSTEM/COMPONENT TESTS .

For Windstar, see SYSTEM/COMPONENT TESTS .

• If CO emissions are excessive, check secondary ignition system. See CIRCUIT TEST JB in appropriate article:

For Contour & Mystique 2.0L, see TESTS W/CODES - 2.0L .

For Contour & Mystique 2.5L, see TESTS W/CODES - 2.5L .

For Windstar, see TESTS W/CODES .

• If ignition system is okay, check fuel delivery system. See CIRCUIT TEST HC in appropriate TESTS W/CODES article. If fuel system is okay, check PCV system. See CIRCUIT TEST HG in appropriate TESTS W/CODES article. If PCV system is okay, check exhaust system for restriction. See CIRCUIT TEST HF in appropriate TESTS W/CODES article. If exhaust system is okay, check engine compression. Check engine mechanical condition. Check intake manifold gasket, camshaft and valves.