Fuel Injector

The SFI fuel injector assembly is a solenoid-operated device, controlled by the PCM, that meters pressurized fuel to a single engine cylinder. The PCM energizes the (12.0 ohms) solenoid to open a normally closed ball valve. This allows fuel to flow into the top of the fuel injector, past the ball valve, and through a recessed flow director plate at the injector outlet. The director plate has four machined holes that control the fuel spray, generating a conical spray pattern of finely atomized fuel at the valve, causing it to become further atomized and vaporized before entering the combustion chamber.

A fuel injector that is stuck partly open or leaking would cause a loss of fuel pressure after engine shut down, so long crank times would be noticed on some engines. Dieseling also could occur because some fuel could be delivered to the engine after the ignition is turned to the Off position.




The fuel injection system on both SOHC and DOHC engines utilize sequential fuel injection. The PCM independently controls each fuel injector. The PCM grounds each fuel injector circuit for a certain length of time based on engine operating parameters. The fuel control system is designed to maintain a 14.7 to 1 air/fuel ratio under all engine running conditions except power enrichment (heavy acceleration/heavy engine load) and deceleration modes. The PCM can turn fuel injectors Off during deceleration, misfire diagnostics and traction control.