Patent ID: 7725240

Claim:
An injector control unit for an internal combustion engine, the engine comprising a plurality of cylinders, each one of the cylinders comprising a combustion chamber into which fuel is injected by an associated fuel injector and within which, in use, combustion events repeatedly occur to define a combustion cycle of the cylinder between successive combustion events; wherein the injector control unit is arranged to determine an injection timing correction and comprises: an observer for calculating a series of combustion cycle speeds; and a correction controller for determining an injection timing correction; wherein the observer includes: an input for receiving at least one signal relating to the speed of the combustion cycles of the cylinders; and an observer memory comprising a plurality of buffers for storing the series of combustion cycle speeds; wherein the observer is arranged to determine a series of speed fluctuation levels from the combustion cycle speeds; and wherein the correction controller includes: an input for receiving the speed fluctuation levels from the observer; a memory for storing a threshold speed fluctuation level; a comparator for determining if the speed fluctuation levels are abnormal with respect to the threshold speed fluctuation level; a logic element to determine, by a logic operation, if abnormal speed fluctuation levels are occurring in all of the cylinders of the engine; and an output for outputting an injection timing correction.