Fuel Injectors

Fuel injectors are electric solenoid valves controlled by Powertrain Control Module (PCM). The Auto Shutdown (ASD) relay provides voltage to one side of fuel injector. The PCM initially energizes all fuel injectors at the same time at start-up by completing ground circuit for each fuel injector. When fuel injector is energized, the armature and needle inside fuel injector move a short distance against spring, allowing fuel to be delivered in a fine atomized spray.

Once PCM determines crankshaft position, PCM energizes fuel injectors in sequence by controlling ground circuit for each fuel injector. This is referred to as Sequential Fuel Injection (SFI). The PCM uses various input signals to determine the length of time fuel injector is energized (pulse width) by switching on and off the ground circuit for each fuel injector.