Apparatus for detecting an occurence of misfiring in an engine cylinder

摘要

In a misfire detecting device for an internal combustion engine having a plurality of cylinders, revolution detecting device detects the revolution of an engine; arithmetic device calculates deflections in revolution of the engine for each of the cylinders on the basis of a period of revolution of the engine in correspondence to the order of combustion of the cylinders; threshold value determining device determines a misfire decision threshold value for the cylinders from a value obtained by smoothing arithmetic values which are determined for the cylinders by the arithmetic device, and a predetermined value; and misfire deciding device compares the arithmetic values provided by the arithmetic device with the threshold value to comparison, to determine the occurrence of a misfire in any one of the cylinders.