Symptom Checks

Check the following items:

• If engine idles fast at idle, turn ignition off. Turn ignition switch to ON position. Using scan tool, select TP V and TPREL PIDs from PID/DATA monitor menu. Check the following PID values: TP V and TPREL while wiggling TP sensor circuits. At vehicle start, TPREL PID reading will begin at about 1.25 volts and count down to the lowest TP V value since engine start-up. If TP V value goes below normal range, then increases again, TPREL will set to lower voltage. If TP V is about .04 volts greater than TPREL value at closed throttle, PCM will go into part throttle mode. Check for loose or worn throttle plates. If no concern is found, see TEST Z under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article and check for intermittent faults.
• Check air intake system. See TEST HU under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article. If air intake system is okay, return to SYMPTOM DIAGNOSIS  to identify any additional symptoms or see TEST Z under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article and check for intermittent faults.