Injection Timing

All engines use a Sequential Fuel Injection (SFI) system. Injectors have a specific firing order and fuel injection is timed to piston movement. Spark plugs and injectors are fired in order:

• 1-3-4-2 on 2.4L and 2.5L engines.
• 1-6-5-4-3-2 on 3.7L engine.
• 1-5-3-6-2-4 on 4.0L engine.
• 1-8-4-3-6-5-7-2 on 4.7L engine.

Order for PCM to fire injectors in a specific order timed to crankshaft and piston movement, it has to establish a reference point. Establishing a reference point requires PCM inputs from the CKP sensor and CMP sensor. PCM will not allow engine to operate if CKP sensor signal is not received.