Fuel Injection Engine

Fuel Injection

Your gas pedal is connected to the throttle valve that leads to the fuel injection. This valve regulates the amount of air that enters the engine. In a way, the gas pedal is more like an “air pedal” when you think about it.

The engine control unit (or ECU) is a computer that controls all of the electronics on your engine), so when you press the pedal to open the throttle valve and let in more air, the ECU detects this and increases the fuel rate to match the extra air entering the engine. It is important to increase the fuel rate right when the throttle valve opens. If this doesn’t happen, there may be a pause when the air reaches the cylinders without enough fuel in it.

Other sensors monitor the amount of air entering the engine, temperatures, and even the amount of oxygen in the exhaust. The ECU uses all of these bits of information to fine-tune the air-to-fuel ratio.

The Injector

A fuel injector is a valve that is electronically controlled. Supplied with pressurized fuel from the fuel pump , it is capable of opening and closing many times per second.

Inside a fuel injector

Inside the fuel injector, an electromagnet moves a plunger in order to open the valve, allowing pressurized fuel to spray out from a tiny nozzle. The nozzle turns the fuel into a light mist so it can burn more easily.

Fuel Injector firing fuel injection

A fuel injector firing

The amount of time the fuel injector remains open determines how much fuel is supplied to the engine. The amount of time it stays open is called the pulse width, and it is also controlled by the ECU.

fuel injection fuel injectors on rail

Fuel injectors mounted in the intake manifold of the engine

The injectors are placed in the intake manifold so that they spray fuel directly at the intake valves. The fuel rail is the pipe that supplies pressurized fuel to all the injectors.

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