Symptom Checks

Check the following items:

• Check the following Parameter Identification (PID) values: DPFEGR, LONGFT 1, LONGFT 2 and VPWR. See appropriate PIN VOLTAGE/PID VALUE CHARTS article. On some models, DPFEGR PID may not be applicable. If DPFEGR PID voltage is not .2-1.3 volt with Key On Engine Off (KOEO), see TEST HE , step 100)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article. If LONGFT 1 or LONGFT 2 PID value is low (-20 percent), concentrate checks in areas that would cause engine to run rich. If LONGFT 1 or LONGFT 2 PID value is high (+20 percent), concentrate checks in areas that would cause engine to run lean. If VPWR PID voltage is not 10.5-17.0 volts check and repair charging system as necessary. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If VPWR PID voltage is 10.5-17.0 volts but not within .5 volt of battery voltage, check battery supply circuit to power relay (or CCRM) and VPWR circuit between PCM and power relay or CCRM, and PWR GND circuits. See WIRING DIAGRAMS article.
• If engine idles rough at idle, turn ignition off. Turn ignition switch to ON position. Using scan tool, select INJxF PIDs from PID/DATA monitor menu. There is one INJxF PID available for each engine cylinder and the "x" indicates the appropriate injector number (1-10). If any PID value indicates YES, an injector fault exists. Turn ignition switch to OFF position and disregard any DTCs that are present at this time. On Natural Gas models, see TEST HA , step 60)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article. On all other models, see TEST H , step 56)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• If engine stalls with A/T in Park or Neutral, check Idle Air Control (IAC) system. See TEST KE , step 2)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check secondary ignition system. See TEST JB under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check fuel delivery system. On Natural Gas models, see TEST HB . On all other models, see TEST HC under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check exhaust system for restriction. See TEST HF under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check PCV system. See TEST HG under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• On natural gas vehicles, check injector circuits between Natural Gas (NG) module and injectors. See TEST HA , step 57)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• On A/T models, ensure transmission is functioning properly. If engine stalls during transmission engagement, check transmission solenoids. See appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.
• Check EVAP Emission system for blockages (engine stalls) or leaks (excessive fuel odor). See SYSTEM TESTS (EVAPORATIVE EMISSIONS) in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check engine mechanical condition. Check compression, camshaft, valve train components, etc. and repair as necessary. See appropriate article in ENGINES.
• Check air intake system, see TEST HU under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• On Continental, LS and Windstar, with A/C on, if there is any idle concerns, see TEST DS , step 22)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check for engine surge with cruise control on. Check for engine surge with A/C on. On models with rolling idle and/or engine stumbles when A/C cycles on, check A/C compressor diode. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. If no problems are indicated, return to SYMPTOM DIAGNOSIS  to identify any additional symptoms or check for intermittent faults. See TEST Z under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.