An Overview of EFI Fuel Injection Systems

The first EFI system was known as the Electro injector, designed in 1957. EFI means electronic fuel injection. The EFI fuel injection system is fitted to most modern vehicles. The EFI fuel injection systems basically combine a high-pressure fuel delivery system with modern computer controls to provide the engine optimum power and fuel efficiency. The whole EFI fuel injection systems are controlled by the ECU or the electronic control unit.

The EFI fuel injection systems have most of the time a huge number of engines and emission sensors, sending information to the ECU. The electronic control unit then monitors all the information it received from the engines and the sensors and then ensures that the correct amount of air and fuel is utilized to provide the most optimum fuel efficiency. It also ensures performance and minimizes exhaust emission.

Different Types of Fuel Injection

EFI Fuel Injections
EFI Fuel Injections

There are basically four different types of fuel injection:

  • Single-point Injection (or throttle-body injection): It is known to be one of the oldest and the most simplistic type of fuel injection. What single point does is that it changes the carburetor and then replaces it with a single or double fuel injector nozzles.
  • Multi-point fuel injection: Multi-point fuel injection has a different nozzle for injecting for each cylinder which is situated right outside of what is known as the intake port. This is why this type of system is also known as port injection. It shoots the fuel vapor at such a short distance which makes sure that it will completely travel through the cylinder.
  • Sequential Fuel Injection: Also known as sequential port fuel injection or SPFI or even timed injection. It is a type of multi-port injection. Basic MPFI also has multiple injectors, but they spray fuel all at a parallel time, due to which, the fuel stays in the port for something like 150 milliseconds and that’s huge for engineers to look into it. Sequential fuel injection sprays to each nozzle independently and it doesn’t look like much but it’s a huge step to efficiency and improvements.
  • Direct injection: Direct injection means just as its name suggests. It directly injects fuel past the valves into the combustion chambers. This is particularly similar in diesel engines. Direct injection has a lot of advantages like fuel metering, which is far more accurate than separate injection systems, and the fuel injection gives the engineers a very good idea about how combustion occurs in the engines.

 How EFI Fuel Injection Systems Does Works?

EFI Fuel Injector
EFI Fuel Injector

The main basic difference between EFI fuel injection systems and mechanical ones is that in the case of EFI, the whole process is controlled by the ECU which is very much like a mini computer. This ECU is fed with all the information it needs from various sensors on the engines. Like for example air pressure, a temperature in the air intake, accelerator position, engine temperature and even engine speed. All these various information makes the ECU decide on the fuel flow, and provide efficiency rather than the mechanical injection in which the only factor it takes into consideration is sensing the air flow.

Then, the ECU compares the information it got from the practical experience with the theoretically accurate information, which was coded inside it from the factory and decides accordingly the things like how much fuel should be delivered to the engine etc. The most amazing part of all this is that everything occurs in a fraction of a second.

Along with the improved control overflow, the EFI fuel injection systems also run on a lower pressure as compared to a mechanical injection system which ultimately makes the whole system run a lot quieter than mechanical injection system.

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