Fuel Injectors
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The fuel injectors are electrical solenoids. The injector contains a pintle that closes off an orifice at the nozzle end. When electric current is supplied to the injector, the armature and needle move a short distance against a spring, allowing fuel to flow out the orifice. Because the fuel is under high pressure, a fine spray is developed in the shape of a pencil stream. The spraying action atomizes the fuel, adding it to the air entering the combustion chamber. An individual fuel injector is used for each individual cylinder. The top (fuel entry) end of the injector is attached into an opening on the fuel rail. The nozzle (outlet) ends of the injectors are positioned into openings in the intake manifold just above the intake valve ports of the cylinder head.
The Fuel Injectors are supplied voltage from the Automatic Shut Down (ASD) Relay Output circuit. The PCM controls the operation of the injectors through a Pulse Width Modulated (PWM) Low Side Driver (LSD). Each injector receives a unique pulse width based on that cylinder's fuel requirements. The PCM determines this fuel requirement by monitoring engine operating parameters through various sensors and then calculating the appropriate amount of fuel to be injected. The optimum amount of injected fuel depends on conditions such as engine and ambient temperatures, engine speed and workload, and exhaust gas composition.