Hello Guys I am here to give information on fuel injection which are mostly used in automotive engines and have replaced carburetor.
Fuel injection is the process of injecting fuel into the internal combustion engine, using an injector. It is a replacement for carburetor.
Types of Fuel Injectors:
Throttle body injectors or Single Point Injector’s (TBI):
This is the simplest form of Fuel Injection which was the replacement for carburetors. It has one or two fuel injectors on the throttle body which delivers the aspect ratio of the fuel-air mixture to every fuel intake manifold in the engine. The drawback was the cylinder closest to the injectors gets a better fuel mixture than the cylinders away from it. The reason TBI replaced carburetor was TBI would easily adjust according to air density and altitude, and were independent of the vacuum manifold.
Port or multi-point fuel injection (MPFI):
Unlike TBI, MPFI has separate injectors for every cylinder, which means better fuel mixture in all cylinders. If the engine has 4 cylinders it will have 4 fuel injectors located at the intake port of the manifold. The fuel is misted at the intake manifold, since it is misted so close to the intake manifold, it ensures full combustion of the sprayed fuel making it more efficient than TBI and provide better fuel efficiency. This allows more even fuel distribution. MPFI lessens the possibility that fuel will condense in the intake manifold.
Sequential fuel injection (SFI):
It is the same as MPFI, MPFI injects fuel at the same time but Sequential fuel injection triggers each injector nozzle independently and is timed like spark plugs. SFI sprays the fuel immediately before or as the intake valve opens. There is not much difference between SFI and MPFI but the spray timing makes the difference. This correct timing of spraying fuel has improved efficiency and emission.
DI is one of the advanced fuel injection technology so far. Direct Injection is mostly used in diesel engines but it is making its way to petrol engines slowly. In DI the fuel is directly sprayed in the combustion chamber of the cylinder. As the fuel is directly injected there is no wastage of fuel or any carbon deposit on the intake valve. The ECU senses the amount of fuel required and only that amount is supplied. Indirect injection fuel metering is more precise than any other system.
Courtesy: Engineering Explained