Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Lack/loss of power - Hard start - Engine hesitation

Possible Causes

- Faulty spark plug 4 - Faulty ignition coil 4 - Ignition coil 4 harness is open or shorted - Ignition coil 4 poor electrical connection - Clogged or faulty fuel injector 4 - Injector 4 harness is open or shorted - Injector 4 poor electrical connection - Improper spark plug 4 - Insufficient cylinder 4 compression - Incorrect fuel pressure - Intake air leak

When Detected

Engine Cylinder 4 is Misfiring.

Description

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.