Although more electronically controlled fuel injection system each cylinder has a jet, the jet injector of the pulse width is determined by the amount that is depends on the jet injector open time. However, specific to different injection form, but not all, of the more general Fuel Injection System (MPI) and sequential fuel injection (SFI) points.

In MPI system, the jet was divided into several groups, the same group of the jet at the same time has been opened. For example, a 4-cylinder machine jet divided into two groups, each of the two jet, which the two groups take turns jet injection, the engine crankshaft every lap to a group of jet injector. Such a system is the jet parallel, ECU only to the same group all the same signal injector, the injector in the same amount of time opening and closing, programming simple, streamlined electronic circuits, but it's different for the engine The lack of random changes in the status of the function will produce oil and gas in the inlet manifold stranded phenomenon.

SFI system in a jet connect directly with the ECU, respectively control, it can be precise injector opened just before the intake valve is opened, injector fuel injection period between the two can do instantaneous adjustment of the gas mixture features to adapt to different conditions change. Therefore SFI is electronically controlled multi-point fuel injection system in the most accurate and the best way, many car engines have adopted this approach.