Fuel Injectors

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The PCM controls fuel injector pulse width ("on" time) to meter fuel quantity into intake ports. PCM receives inputs from engine sensors to compute fuel flow necessary to maintain correct air/fuel ratio throughout entire engine operating range. Injector pulse width is the only controlled variable in fuel delivery system.

Each cylinder has a solenoid-operated injector that sprays fuel toward the back of each intake valve. Fuel injector nozzles are solenoid-operated valves, which meter and atomize fuel delivered to engine. Each injector receives battery voltage through an ignition switch circuit. The PCM controlled ground circuit is used to complete the circuit and energize the injector.

Injector bodies consist of solenoid actuated pintle and needle valve assembly. See Fig 1. Injector flow orifice is fixed and fuel pressure at injector tip is constant. Fuel flow to engine is regulated according to length of time solenoid is energized. Atomized spray pattern is obtained by shape of pintle.

Fig 1: Cross-Sectional View Of Fuel Injector Assembly

Courtesy of FORD MOTOR CO.