Fuel Injectors Explained

How the engine works nowadays had changed more rapidly and more extensively in the last few years than in the preceding decades. There's not a single new car in the country or probably on this planet, selling currently with a carbureted engine. Carburetors are gone for good! Which now leads us to fuel injectors, carburetors were brainless - did not precisely inject the fuel. However, fuel injectors are smart they are backed-up by ECU (electronic-control-unit) aka their brain. And they know how much fuel is required in the particular moment. Thus optimum performance, controlled emission and not-to-miss better fuel efficiency compared to carbureted engines!

How Does FI work?

Don’t worry it’s not a rocket science! Fuel is pumped from the tank using an electric fuel pump which indeed placed inside the tank itself. The fuel pump then sends the pressurised fuel into the fuel lines which carries it to the engine and to the injectors at last. Now, ECU aka Electronic Control Unit comes into play, ECU analyses how much fuel is required by the engine at the very moment and signals the fuel injectors the same. Moreover, ECU also analyzes the amount air entering the combustion chamber along with the throttle position using accelerator pedal position (APP) sensor; before opening the injectors for spraying. It’s always a busy day for ECU because apart from these lot of other sensors keep buzzing it and all the data is important for the amount of fuel sprayed.

How it actually happens, the injectors are connected to the electric supply along with the signals from the ECU. Courtesy to the electric supply, the solenoid’s magnetic field attracts the magnet on top of the plunger of the fuel injector. This opens the injector valve and sprays the pressurized fuel coming from the electric fuel pump through its tiny nozzle. Moreover, the duration of the valve opening depends on the signals from the ECU and further depending upon the engine conditions.

Two Types of Injection systems

There are two ways in which a fuel injector injects fuel in the combustion chamber - MPFI (Multi Point Fuel Injection) and DI (Direct Injection). Petrol engines have shed carburetors while diesel engines are done with injector pumps. In an MPFI engine, the fuel injector sprays fuel into the intake manifold while in DI - the injectors spray fuel, as the name indicates, directly into the combustion chamber. Diesel engines have been using DI tech for quite long while petrol motors have started using it as they are downsizing the engine displacement, charging it with a turbocharger in DI setup. Moreover, MPFI is still popular in non-turbocharged petrol motors.

Port Fuel Injection - MPFI

Direct Injection