PCM Function

PURPOSE
The Engine Control Module (ECM) contains memories for the basic fuel injector discharge timing and duration at various engine speeds and manifold pressures.

When the engine is cold, the A/C compressor is on, the transmission in gear (A/T only) or the alternator is charging, the ECM controls current to the Idle Air Control valve to maintain correct idle speed.

The ECM contains memories for basic ignition timing at various engine speeds and manifold pressures. Ignition timing is also adjusted for coolant temperature. The ignition timing control is electronic with no vacuum or mechanical distributor controls.