Method and apparatus for gaseous fuel introduction and controlling combustion in an internal combustion engine

A method and apparatus for introducing gaseous fuel into a piston cylinder of an operating internal combustion engine in two separate stages involves monitoring a set of engine parameters, determining engine load and engine speed from the set of engine parameters, in a first stage, introducing a first portion of the gaseous fuel into the cylinder where the first portion of gaseous fuel forms a substantially homogeneous mixture comprising gaseous fuel and air prior to combustion, and in a second stage, occurring sequentially after the first stage, introducing a second portion of the gaseous fuel into the cylinder. The gaseous fuel quantity is variable in response to a least one of engine load and engine speed. Initiation and duration for at least one of the first and second stages is also variable in response to at least one of engine load and engine speed.