IAC SYSTEM RPM HIGH
PCM controls idle speed with an Idle Air Control (IAC) valve
to a calculated RPM based on sensor inputs and actual engine RPM. PCM
moves IAC valve in or out to vary amount of airflow into intake
manifold and thus decrease or increase idle RPM.
PCM commands IAC in counts. A higher count, allows more air
to by-pass throttle plate (higher idle).
You may only notice a high then normal idle
- Vacuum leak
- A faulty (PCV) positive crankcase ventilation valve
- Dirty throttle body
- Failed EVAP system
- Faulty or Failed IAC (idle air controller)
- Check for vacuum leak
- Check PCV valve, replace if needed.
- Clean throttle body
- Inspect EVAP system, repair if needed
- Inspect IAC, replace if needed