Engine Ignition

ENGINE IGNITION

The electronic ignition (EI) system for the 3.9L and the 4.2L engines consists of the following components:
- crankshaft position (CKP) sensor
- ignition coil
- spark plugs
- spark plug wires

The crankshaft position (CKP) sensor:
- is a variable reluctance sensor.
- is mounted on the engine front cover.
- is triggered by a 36-minus-1 tooth trigger wheel located on the crankshaft pulley and damper.
- provides base timing and crankshaft speed (rpm) to the powertrain control module (PCM).

The ignition coil:
- is controlled by the powertrain control module.
- fires two spark plugs simultaneously.

The spark plugs:
- ignite the fuel and air mixture.
- are platinum enhanced for long life.

The spark plug wires:
- carry high voltage pulses from the ignition coil to the spark plugs.