Sequential Fuel Injection (SFI)

SFI vehicles can operate in one of 2 injection modes: simultaneous or sequential. In simultaneous injection mode, fuel is injected simultaneously into all cylinders twice each engine cycle. In sequential injection mode, injectors are triggered in firing order individually. Fuel injectors operate in sequential mode under most conditions. Fuel injection will shift from sequential to simultaneous mode during starting or when ECM is operating in fail-safe mode.