Nippondenso Co., Ltd.

Isamu Nomura

Masaaki Nakayama

Hideki Morishima

Akira Ichikawa

Yasuhito Takasu

Kouichi Shimizu

Yasutoshi Baba

In a misfire detecting apparatus for a multicylinder internal combustion engine, a rotational signal outputting unit outputs a rotary signal at every predetermined rotary angle, and a tentative misfire decision unit tentatively decides, on the basis of the rotary signal, whether or not misfire has occurred in each cylinders of the engine. A tentative misfire number counting unit counts the number of tentative misfires decided for respective cylinders, and a counting result storage unit stores the counting results. After a given number of tentative misfire decisions have been made, it is decided that misfire has actually occurred, only if the counting result, for a part of the cylinders, among the counting results for respective cylinders stored in the counting result storage unit is larger than a predetermined number.

Misfire detecting apparatus for multicylinder internal combustion engines

An apparatus for detecting occurrence of misfire in a multicylinder internal combustion engine detects a rotational speed of the engine in each expansion stroke of each cylinder, calculates a change of the engine rotational speed fluctuation quantity in accordance with a value of the detected rotational speed, and sets a misfire determination value for each cylinder based upon a determination result of the engine operating condition. Misfire determination is made for each cylinder based upon the misfire determination value for each cylinder and the change of the rotational speed fluctuation quantity, thereby elevating the accuracy of detecting occurrence of misfire in each cylinder.

Apparatus for detecting misfire in multicylinder internal combustion

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Obu, Japan

Isamu Nomura