Fuel Injector: Description and Operation

Fuel Injector - Cutaway View:

PURPOSE

Enables PCM to compensate for varying engine operating conditions by controlling the amount of fuel injected, precisely.

- Atomizes fuel for more complete combustion.

- Sprays fuel into intake manifold, above intake ports, in an even, conical pattern.

OPERATION

When an injector solenoid is energized, the plunger is retracted, lifting needle valve off seat, allowing the pressurized fuel to spray into the intake manifold.

When the solenoid is de-energized spring pressure closes valve.

Since the injector nozzle is a fixed size and fuel pressure is regulated (at 48 psi), the amount of fuel injected changes only when the amount of time the injector is energized per cycle changes. (This period of time is called "injector pulse width".)