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 HOT IDLE PID value is not within .15 volt of KOEO value, go to TEST HE, step 100)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & 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 value 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 B+ circuit to power relay (or CCRM), VPWR circuit between PCM and power relay or CCRM, and PWR GND circuits. See WIRING DIAGRAMS article.
• If engine runs rough at idle, turn ignition switch to OFF position. Turn ignition switch to ON position. Using scan tool, select INJxF PIDs from PID/DATA MONITOR & RECORD menu. There is one INJxF PID available for each engine cylinder and the "x" indicates the appropriate injector number (1-10). If any INJxF 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, go to TEST HA, step 60)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article. On all other models, go to TEST H, step 56)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• If engine stalls with A/T in Park or Neutral, check Idle Air Control (IAC) system. Go to TEST KE, step 2)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Check Mass Air Flow (MAF) sensor. Go to TEST DC, step 25)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Check secondary ignition system. Go to TEST JB, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Check fuel delivery system. On Natural Gas models, go to TEST HB, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article. On all other models, go to TEST HC, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Check exhaust system for restriction. Go to TEST HF, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Check PCV system. Go to TEST HG, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• On natural gas vehicles with rough idle, check injector circuits between Natural Gas (NG) module and injectors. Go to TEST HA, step 57)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Check EVAP emission system for blockages (engine stalls) or leaks (excessive fuel odor). Service appropriate symptom under SYSTEM TESTS (EVAPORATIVE EMISSIONS) in SELF-DIAGNOSTICS - EEC-V - CNG & 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 engine mechanical condition. Check compression, camshaft, valve train components, etc. and repair as necessary. See appropriate article in ENGINES.
• Check air intake system, go to TEST HU, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• On Continental, LS and Windstar, for idle concerns with A/C on, go to TEST DS, step 22)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• For additional intermittent testing, go to TEST Z, step 1)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.
• Ensure Powertrain Control Module (PCM) Vehicle Identification (VID) block is correct. Check engine RPM/speed limiting functions of PCM (proper high vehicle speed signal from ABS, VSS or OSS). Check cruise control system if engine surges with cruise control on. See appropriate CRUISE CONTROL SYSTEMS article in ACCESSORIES & EQUIPMENT. If engine surges with A/C on, or has a rolling idle and/or engine stumble when A/C cycles on, check A/C system and A/C compressor diode. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.