Honda Giken Kogyo Kabushiki Kaisha

Gaku Hatano

Yuji Fujiki

Sachito Fujimoto

Yasunari Seki

Kojiro Tsutsumi

Hideo Moriwaki

Hisashi Daicho

Yoshiaki Matsuzono

Hisato Shimizu

Masahiro Yamada

A misfire state discrimination system of an internal combustion engine, which determines the occurrence of misfire under engine operating conditions that make misfire determination possible and counts the number of misfires to compare with a reference value. The misfire state of the engine is discriminated based on the result of comparison. In the system, when the engine operation moves from the conditions that makes the misfire determination possible, the count is saved and is counted up from the count when the engine operation returns to the condition. The saved count is also retained when the engine is stopped. Similarly, the number of combustion during which the determination of misfire occurrence is made is counted and the count is saved. This arrangement enables a rapid and accurate discrimination of the misfire state of the engine.

Misfire state discrimination system of internal combustion engine

A catalyst deterioration-determining system for an internal combustion engine has a catalyst arranged in the exhaust system, for purifying exhaust gases emitted from the engine, an oxygen concentration sensor arranged in the exhaust system at a location downstream of the catalyst, for detecting the concentration of oxygen present in the exhaust gases, and an ECU which controls the air-fuel ratio of an air-fuel mixture supplied to the engine in a feedback manner in response to the output from the oxygen concentration sensor. Determination of deterioration of the catalyst is carried out based on the output from the oxygen concentration sensor during execution of air-fuel ratio feedback control. An inversion period parameter representative of a repetition period of change in the output from the oxygen concentration sensor over a predetermined diagnosis period is measured, and a determination parameter is calculated by averaging values of the inversion period parameter measured over different diagnosis periods as the predetermined diagnosis period. The determination of deterioration of the catalyst is carried out based on the determination parameter.

Catalyst deterioration-determining system for internal combustion engines

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Woko, Japan

Gaku Hatano