MultiPort Fuel Injection
MultiPort Injection systems use separate fuel injector for each cylinder so that fuel can be sprayed directly into the cylinder head intake port. When air flows through the intake manifold, the intake manifold remains dry and there are no problems with fuel puddling or fuel separation causing uneven fuel mixtures in the center and end cylinders. MultiPort Injection allows the fuel mixture to be uniform in all of the cylinders for better fuel economy, emissions and performance.
Early production Multiport fuel injection systems were mechanical rather than electronic and date back to the 1950′s. In the late 1970′s fuel injection systems such as the Bosch L-Jetronic systems replaced mechanical injectors with electronic injectors. In today’s vehicles, all production fuel injection systems are fully electronic with computer controls and electronic injectors (EFI).
Most of the EFI systems used in the late 1980′s and early 1990′s operate by firing all injectors simultaneously with every revolution of the crankshaft. With more sophisticated Sequential Fuel Injection (SFI) systems that were introduced later would fire each injector separately, normally just after the intake valve is opening. This allows a much more precise fuel control for better performance, fuel economy and emissions.