Fuel injection is the phenomenon of fuel introduction in a car’s combustion chamber. It is achieved through fuel injectors, which are responsible to inject the right quantity of fuel into the engine for it to run smoothly. All modern cars are now equipped with fuel injectors.
In this guide, we will discuss what a fuel injector is, its benefits, its different types, and how to clean fuel injectors.
What is a Fuel Injector and What Does it Do?
A fuel injector is an electronically controlled valve that can open and close multiple times in a second. It is supplied with pressurised fuel from the car’s fuel pump and injects the required amount into its combustion chamber through a nozzle.
The design of the nozzle is such that it atomizes the fuel to turn it into a fine mist that can burn easily. The amount of fuel supplied to the combustion chamber is determined by the time the valve remains open. This phenomenon is called pulse width and is controlled by different car sensors equipped in the engine control unit.
Benefits of Fuel Injectors
Since the mid-1980s, fuel injectors have become a primary means of fuel delivery in cars. There are several benefits of fuel that have been detailed below.
Fuel Economy
As compared to a carburettor, a fuel injector prevents fuel wastage by providing an accurate quantity of fuel for the air-fuel mixture. This increases fuel economy and reduces the carbon footprint of cars.
Engine Efficiency
By providing the right quantity of fuel in the combustion chamber, the air-fuel ratio is maintained resulting in better combustion. This, in turn, increases engine efficiency.
Fuel Metering
A fuel injector precisely metres the fuel and maintains the air-fuel ratio through the car’s engine control unit (ECU). Thereby, fuel injectors aid in fuel efficiency.
Prevents Detonation and Knocking
Detonation and knocking are some examples of engine malfunctioning that occur due to incomplete combustion. It was usually observed in carburettors, where the improper mixing of air and fuel often led to unburned particles in the combustion chamber. This problematic event has now been eliminated by equipping cars with a fuel injection system.
Types of Fuel Injectors
Different fuel injection arrangements like multi-point fuel injection, throttle body fuel injection, sequential fuel injection, and direct injection have been introduced since the advancement of fuel injectors. Fuel injectors can be classified based on fuel and fuel metering.
Types of Fuel Injectors – Based on Fuel
Fuel injectors are further classified into two types based on fuel.
Diesel Fuel Injectors
These fuel injectors spray diesel or inject it into the combustion chamber, for combustion by compression. The diesel fuel injectors require higher injection pressure as diesel is denser than petrol.
The design of diesel fuel injectors allows the spraying of diesel packets into the chamber through the nozzles.
Petrol Fuel Injectors
The petrol fuel injectors spray petrol or inject it into the combustion chamber of a car’s engine for further combustion by spark initiation.
The nozzles of petrol fuel injectors are smaller than those of petrol fuel injectors since petrol has a lesser density than diesel and requires lesser pumping pressure.
Types of Fuel Injectors – Based on Fuel Metering
Fuel metering is termed for controlling the speed, pressure, and amount of fuel. Based on fuel metering, fuel injectors can be classified into two types.
Mechanically Controlled Fuel Injectors
As the name suggests, in mechanically controlled fuel injectors, fuel metering is controlled mechanically through a spring and plunger. Such injectors take input from the cam and fuel pump arrangement or by fuel distributor.
Electronically Controlled Fuel Injectors
Those fuel injectors in which fuel metering is controlled electronically through an electronic solenoid are called electronically controlled fuel injectors. This type of fuel injector requires input from various engine sensors.
This allows the car computer to determine the engine’s operating conditions and adjust the fuel mixture as needed. Ensure that your car doesn’t have a bad engine control module as it may result in high fuel consumption due to incorrect proportion of air-fuel mixture.
How to Test Fuel Injectors with a Multimeter?
Testing fuel injectors with a multimeter requires three simple steps. These steps are as follows:
Step 1 – Locate the Fuel Injector
To test whether you are dealing with a bad fuel injector or not, you must locate it first. The fuel injector is located under the hood of a vehicle. Since most cars have four cylinders, the fuel injectors are four as well. You can use your car’s manual to locate the fuel injectors easily.
The fuel injectors are connected to the fuel rail, so they can be revealed after lifting off the fuel rail.
Step 2 – Setting the Digital Multimeter
To test the injector using a digital multimeter, the multimeter must be set up for ohm’s test. Multimeters usually have an Ω (ohm) symbol on the selector switch area. For testing the fuel injectors you must turn the switch to that Ω (ohm) symbol. The black cable must be inserted in the COM port and the red cable in the port that displays the Ω (ohm) symbol of the multimeter. Now you are all set to test your fuel injectors.
Step 3 – Test the Fuel Injectors
The fuel injectors will be tested against their resistance value. The resistance value can be found through the car’s manual or by a Google search.
To test a fuel injector, you must first reveal its two prongs by removing the cover. Place the free ends of both red and black cables on the two prongs of a fuel injector and check the resistance value.
The best fuel injectors have a resistance between ± 0.5 Ω (ohm) of the specified resistance value. For instance, if the specific resistance value of a fuel injector is 16 and the value obtained is more than 16.5 or less than 15.5, it will be considered a bad fuel injector. There are different symptoms that a bad fuel injector exhibits including rough idling, engine misfiring, leaking fuel, and sudden rpm hikes.
That’s the wrap-up to our guide on all about fuel injectors. Since you are now aware of the importance of a fuel injector, you must keep them maintained as per your car maintenance schedule.
Keeping a fuel injector clean from dirt and debris is of prime importance to ensure good engine performance. Besides, a dirty or bad fuel injector may be a sign your car needs fuel induction service to achieve an optimum performance.
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