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How Fuel Injection Systems Work?


    How Fuel Injection Systems Work?

DEFUS-Audi Car Injector-how Fuel Injection Systems Work

The injector is just an electronic control valve. It is provided with pressurized fuel by the fuel pump in the car and can be turned on and off many times per second.

When the injector is electrified, the electromagnet moves the plunger that opens the valve so that pressurized fuel is injected through a small nozzle. The nozzle is designed to atomize the fuel and make the fog as fine as possible so that it can burn easily.

The amount of fuel supplied to the engine depends on how long the injector remains open. This is called pulse width, which is controlled by ECU. The ejectors are mounted in the intake manifold so that they can inject fuel directly into the intake valve. A pipeline called a fuel distribution pipe provides pressurized fuel to all injectors.

DEFUS-Audi Car Injector-how Fuel Injection Systems Work-1

In order to provide the correct fuel quantity under various working conditions, the engine control unit (ECU) must monitor a large number of input sensors. Here are some:

     Mass Air Flow Sensor - Tell Electronic Control Unit to Enter Engine Air Quality.

     Oxygen Sensor - Monitors the amount of oxygen in the exhaust gas so that the electronic control unit can determine the concentration or dilution of fuel mixture and adjust it accordingly.

     Throttle position sensor - monitors throttle position (it determines the amount of air entering the engine), so that the electronic control unit can respond quickly to changes, increase or decrease fuel rate as required.

     Coolant temperature sensor -  allows the electronic control unit to determine when the engine will reach the correct working temperature.

     The voltage sensor monitors  - the system voltage in the vehicle, so that when the voltage drops, the electronic control unit can increase the idle speed (which would indicate the high electrical load).

     Intake manifold absolute pressure sensor - monitoring air pressure in intake manifoldInhaling the engine's air volume is a good indication of how much power it produces; the more air that enters the engine, the lower the manifold pressure, so the reading is used to measure how much power is generated.

     Engine speed sensor - monitors engine speed, which is one of the factors used to calculate pulse width.

DEFUS-Audi Car Injector-how Fuel Injection Systems Work-2

There are two main types of control for multi-port systems: The fuel injectors can all open at the same time, or each one can open just before the intake valve for its cylinder opens (this is called sequential multi-port fuel injection).

The advantage of sequential fuel injection is that if the driver makes a sudden change, the system can respond more quickly because from the time the change is made, it only has to wait only until the next intake valve opens, instead of for the next complete revolution of the engine.