Electronic Fuel Injection

Electronic Fuel Injection

Bought the system but never used it so it's like new.

How EFI Works
A modern multiport EFI system works differently than a carburetor, but it"s still bolted to the same motor and installed in the same car, so it must provide at least the same level of functionality. No venturis here--fuel isn"t introduced into the engine until the injectors spray it into the base of the intake runners, so the only thing that"s mechanically metered is the air that"s sucked through the throttle body. Since the mixture of air and fuel can"t tumble around inside the intake runners, the injectors spray a fine mist of fuel at high pressure, which "forces" it to mix almost instantly with the metered air. Changing the air/fuel ratio is simply accomplished by varying the amount of time that the injectors are spraying fuel (usually measured in pulsewidth, the number of milliseconds each injector is turned on). You can probably imagine how a choke, idle, or enrichment circuit can be designed into this system. It"s easily done by increasing (or decreasing) the pulsewidth to richen (or lean out) the mixture whenever it"s needed. It sounds simple because it is! So let"s break down some of the basic functions of a carburetor and see how an EFI system accomplishes the same tasks with the aid of a computer.