Symptom Checks
WARNING: This page is about a different car, the 1995 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
Perform the following:
- Perform QUICK TEST. See TESTS W/CODES - EEC-IV (4.0L) article. If code is present, perform appropriate CIRCUIT TEST.
- Check power to MAP/BARO sensor. See step 3) of CIRCUIT TEST S in TESTS W/CODES - EEC-IV (4.0L) article.
- Check ignition system. See IGNITION SYSTEMS in appropriate SYSTEM/COMPONENT TESTS - EEC-IV (4.0L) article.
- Check idle speed. See IDLE SPEED & MIXTURE in ADJUSTMENTS - 4.0L article.
- Check Positive Crankcase Ventilation (PCV) system. See EMISSION SYSTEMS & SUB-SYSTEMS in the appropriate SYSTEM/COMPONENT TESTS - EEC-IV (4.0L) article.
- Ensure driveline and transmission are functioning properly.
- Check air intake system. Ensure throttle plate and linkages operate properly.
- Check fuel delivery system. See FUEL SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (4.0L) article.
- Check for restricted exhaust system.
- Check EGR system. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (4.0L) article.
- Check Fuel Evaporation (EVAP) system. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (4.0L) article.
- Check engine mechanical condition. Check compression, camshaft, valve train components, etc.
- Check Heated Oxygen Sensor (HO2S) heater. Go to step 21) of CIRCUIT TEST H in TESTS W/CODES - EEC-IV (4.0L) article.
- Check cooling system (radiator, thermostat, etc.)
- Check customer driving habits (over RPM/speed limiting function enabled).