SFI question.

[loneryder]

Is SFI fuel injected a direct injection system or is it injected before the intake valves?

 

[Kira]

The S stands for sequential.
Usually, direct injection systems are labeled as such.
Ergo, my money's on an SFI system spraying fuel before the intake valves.

 

[ZZman]

Before the valves

 

[vpr5703]

Generally when you hear SFI it is a port-injection system, so before the valves.

 

[I<3oil]

Generally when you hear SFI it is a port-injection system, so before the valves.

This. SFI is a type of multiport injection system.

Sequential Fuel Injection​

Sequential fuel injection, also called sequential port fuel injection (SPFI) or timed injection, is a type of multiport injection. Though basic MPFI employs multiple injectors, they all spray their fuel at the same time or in groups. As a result, the fuel may “hang around” a port for as long as 150 milliseconds when the engine is idling. This may not seem like much, but it’s enough of a shortcoming that engineers addressed it: Sequential fuel injection triggers each injector nozzle independently. Timed like spark plugs, they spray the fuel immediately before or as their intake valve opens. It seems like a minor step, but efficiency and emissions improvements come in very small doses.

 

[bdcardinal]

They started calling it Sequential since the injectors would fire in time with the intake valve opening. Before that you had K-Jet for continuous and batch fire that either fired all the injectors or one bank at a time.