Abstract: A misfire determination apparatus for an internal combustion engine including a rotational speed detector detecting a rotational speed of an engine and a microprocessor. The microprocessor is configured to perform calculating a misfire parameter having a correlation with a change amount of the rotational speed in a combustion stroke of each of a plurality of cylinders and increasing as an increase amount of the rotational speed is large based on the rotational speed detected by the rotational speed detector, and determining that a single-cylinder misfire has occurred when the misfire parameter is less than a first predetermined value, while determining that the single-cylinder misfire or a multi-cylinder misfire has occurred when the misfire parameter is less than a second predetermined value greater than the first predetermined value.

Abstract: A misfire determination device, for an internal combustion engine, according to the present invention detects a combustion state parameter of the internal combustion engine, retrieves an extreme value of the combustion state parameter in an extreme value retrieval section from a start timing of a combustion stroke to a predetermined crank angle (step 5), upon retrieval of the extreme value, sets a predetermined crank angle section subsequent to a crank angle corresponding to the extreme value as a misfire determination parameter calculation section (step 6, expression 5), calculates a misfire determination parameter based on the combustion state parameter that has been detected in the misfire determination parameter calculation section (step 6), and determines a misfire based on the misfire determination parameter (steps 7 to 9).

Abstract: A control apparatus, for an internal combustion engine, detects a rotational speed parameter (time parameter) that represents a rotational speed of the internal combustion engine including a plurality of cylinders, detects a single misfire that is a misfire for every ignition for each of the plurality of cylinders, based on the rotational speed parameter that has been detected in each combustion stroke of the plurality of cylinders (steps 2 to 7 and 9), counts, as a misfire counter value, the number of times that the single misfire has been detected for each of the plurality of cylinders (steps 8 and 10), determines whether the misfire is occurring in the cylinder, based on the misfire counter value (steps 11 to 12), and corrects an ignition timing of the cylinder that has been determined that the misfire is occurring to an advance angle side (steps 25, 26, and 34).