Electronic vs. Mechanical Fuel Injection: A Comparison Guide

January 27, 2012

Mechanical fuel injection is used to indicate the metering functions of the fuel injection system. Carburetor fuel injection is an advancement of the mechanical fuel injection method. The aim of all types of fuel injections systems is to achieve a delivery of the exact air/fuel mix into the combustion engine. All the types of fuel injections try to force the fuel into the combustion engine under a great pressure through injectors. Fuel injectors provide good mileage and power improvements over RPM range of the engine.

Features of Mechanical Fuel Injection

All the fuel injection systems which may be a mechanical system or an EFI system follow only mechanical operations in order to force fuel into an engine. The difference is that the EFI system performs various on and off operations electronically, which are due to a variety of electronic controls present within the EFI system. These tell how and when the fuel must be injected into the engine. This facility is not available in the mechanical fuel injection system.

The optimum ratio of air to fuel varies with the changes occurring in the atmospheric temperature, engine temperature, altitude, engine load and speed, ignition timings, and the gasoline engines. So the fuel injections must be designed in such a way that it must adjust to the engine requirements. Hence the fuel injection system must be able to sense the variations in these parameters. Microprocessors are used in order to serve this purpose. These microprocessors compute whether the correct amount of fuel is injected when it is required or not adjusting to the requirements of the engine.

Usage of Mechanical Fuel Injection

Carburetors were used until 1980 because they are inexpensive, and were consumer friendly. Being frequently used in petrol or gasoline engines. Fuel injection and precision pumps were also used at that time, but were very costly. Hence carburetors became the alternative.

Also, they were incorporated into the engines such as Mopar and GM vehicles. But these became obsolete by the emergence of electronic fuel injection systems. Many American systems were not fully understood and proved to be very unreliable. Consumers switched quickly for the added value, reliability, and merely a more culturally appropriate device enjoyed in carburetors. Then a number of European systems came into existence.

Historically, mechanical injection systems were used only for racing cars and land speed records during 1950 and 1960. Hilborn and Enderle were 2 of the early innovators. This technology was utilized because EFI systems were not culturally relevant and difficult for consumer adaptation. It involved numerous electronic interventions.

EFI and Mechanical Fuel Injection

An EFI injector has special valves which open and close for fuel to enter the engine. They are electronically controlled. EFI sprays the fuel into the open valves in the form of a mist which is very fine. The valves are opened and closed alternatively in order to push the fuel inside. The injector also checks how much fuel is injected into it by a fuel track.

The special feature of EFI fuel injection is that it operates through mechanical sensors within the system. Sensors are included to ensure that the exact amount of fuel is injected at the specific time.

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