Fuel Injection System - question

Toyota characterizes its system as SFI. It is not clear to me what is the difference between the various systems you named.

 

Regarding automotive fuel injection, I am aware of mechanical fuel injection systems and electronic fuel injection systems. Bosch Jetronic is the most notable example of a mechanical system, used in many European brands during the early-70s.

Electronic fuel injection systems can be characterized as two types:

multiport fuel injection, where each cylinder has a separate injector. The engine ECU controls electronic pulses to the injectors which meter fuel into the cylinders. Bosch L-Jetronic is a popular early example. There are European, Asian, and American designs which follow the basic concept. The Prius benefits from a modern implementation of this concept, with an engine ECU that controls spark timing, fuel injection, monitors the status of emissions controls, etc.

throttle body fuel injection, a less-costly design, where one or two injectors are located in a carburetor-like assembly located in the intake manifold. The intake manifold will convey fuel-laden air to the various cylinders. This is an older American design, GM for example used that for a while.