Misfire detection apparatus for internal combustion engine

摘要

A misfire detection apparatus for an internal combustion engine is capable of detecting combustion when an ionic current generated upon combustion is superimposed on a leakage current, even if the ionic current does not contain an increased component. An ionic current detection part (1) detects an ionic current flowing between electrodes arranged in a combustion chamber of the internal combustion engine through ions generated upon combustion of an air fuel mixture therein by impressing a voltage on the electrodes. A tendency recognition part (4-7) recognizes a tendency of a change in the ionic current detected by the ionic current detection part. A threshold determination device (8) sets a threshold for an output of the tendency recognition part. A determination device (10) determines an occurrence of combustion or misfiring in the combustion chamber based on an output of the tendency recognition part and an output of the threshold determination device.