The function of Electronic Fuel Injection (EFI) is the same as that of a carburettor. Namely, it supplies a mixture of air in the correct proportion to the engine so that the fuel can be used to the optimum. This gives an engine better efficiency and longer life. But an Electronic Fuel system is far more complex than a carburettor. It allows the car owner to control and manipulate more parameters than just the airflow into the carburettor.   An Electronic Fuel Injection system uses electronics and a high-pressure pump to spray fuel into the engine. There are different ways in which fuel is injected into the engine. Direct injection systems inject the mixture directly into the engine cylinders. Port injection systems spray the fuel into the intake valve which lets the fuel into the combustion cylinders. Both the electronic injection systems have their pros and cons.   An EFI is fully electronically controlled although the driver can give commands to the system mechanically by the pressure he exerts on the gas pedal. When the gas pedal is pressed, the electronics of the EFI take over instead of the mechanical operation of a carburettor. This process has more control over the proportion of air and fuel in the mixture injected into the engine. The system also has its disadvantages.