Misfire diagnosis apparatus of multi-cylinder combustion engine

摘要

In apparatus and method for recognizing an absence or presence of a misfire in each of cylinders of a multi-cylinder internal combustion engine without influences of a mechanical deviation in a crank angle sensor arrangement and of a combustion state deviation between each of the cylinders, a period of each reference signal (REF) generated from the crank angle sensor arrangement and a fuel combustion state deviation between each of the cylinders, a period of each reference signal (REF) generated from the crank angle sensor whenever an engine crankshaft has rotated through a predetermined crank angle expressed as 720/n (n denotes a number of engine cylinders) is measured by a timer and the determination of the absence or presence of the misfire in each cylinder is based on the measured period of the reference signal for each corresponding one of the cylinders, the measured period being corrected with either or both of first and second correction coefficients (KTi and KKTi) which are derived by learning the corresponding first correction coefficient for the mechanical deviation and by learning the corresponding second correction coefficient for the combustion state deviation.