– Ignition Coil 4 harness is open or shorted
– Ignition Coil 4 circuit poor electrical connection
– Engine may be running rough
The ignition system is controlled by the Powertrain Control Module (PCM) on all engines. Each cylinder is equipped with 1 dual-output coil. Meaning one coil mounts directly over one of the dual spark plugs for 1 high-voltage output.
Battery voltage is supplied to all of the ignition coils positive terminals from the ASD relay. If the PCM does not see a signal from the crankshaft and camshaft sensors (indicating the ignition key is ON but the engine is not running), it will shut down the ASD circuit.
Base ignition timing is not adjustable. By controlling the coil ground circuits, the PCM is able to set the base timing and adjust the ignition timing advance. This is done to meet changing engine operating conditions.
The PCM adjusts ignition timing based on inputs it receives from:
– The engine coolant temperature sensor
– The crankshaft position sensor (engine speed)
– The camshaft position sensor (crankshaft position)
– The manifold absolute pressure (MAP) sensor
– The throttle position sensor
– Transmission gear selection