What does 'EFI' stand for in engine technology?

In engine technology, EFI stands for electronic fuel injection. It describes a system in which an electronic control unit manages injectors that meter and spray fuel into an engine’s intake system or combustion chambers.

EFI replaced the carburetor in most modern gasoline cars because it can measure fuel more precisely across changing conditions. Sensors monitor inputs such as engine speed, throttle position, intake airflow or pressure, and coolant temperature; the control unit then adjusts injector opening time to help maintain the desired air-fuel mixture.

The term is broader than one particular layout. EFI can refer to throttle-body injection, multi-point or port injection, and electronically controlled direct injection. “Electric fuel injection” and “essential fuel injection” are common-sounding distractors, but they are not the established expansion of the acronym.

Electronic fuel injection has roots in the 1950s. Chrysler offered Bendix Electrojector on selected 1958 models, while Bosch later developed related technology into the D-Jetronic system, introduced in 1967.