Abstract

An internal combustion engine has a common shared intake port for each pair of cylinders and having a primary fuel injection system capable of controlling very precisely the distribution of fuel into each cylinder by controlling the duration and timing of each injection pulse. A common fuel injector is provided for each shared intake port and is controlled so as to inject fuel into the shared intake port only during the specific intake strokes of individual cylinders. Each injector preferably takes the form of an electronic fuel injector coupled to a controller receiving signals from engine mounted sensors such as a crank angle indicator. Such electronic control permits very precise control of the duration and timing of the fuel injection pulse and also enables other injection strategies such as a skip-fire operation in which fuel injection is withheld during selected intake strokes of selected cylinders, thereby eliminating firing cycles corresponding to the selected intake strokes. The fuel injection system is usable with both compression ignition and spark ignition engines and may employ additional primary injectors and/or liquid fuel pilot injectors.