| 摘要 |
PROBLEM TO BE SOLVED: To provide a very practical and highly accurate apparatus for detecting abnormal air-fuel ratio variation among cylinders of a multicylinder internal combustion engine. SOLUTION: This apparatus has a catalyst element 11 purifying hydrogen contained in exhaust gas, a first air-fuel ratio sensor 17 detecting the air-fuel ratio of the exhaust gas that has not passed through the catalyst element, a second air-fuel ratio sensor 18 detecting the air-fuel ratio of the exhaust gas that has passed through the catalyst element, and a means detecting abnormal air-fuel ratio variation among cylinders based on a separation state to the lean side of a second air-fuel ratio detecting value to a first air-fuel ratio detecting value. An injector causes failure in a partial cylinder, and when the air-fuel ratio is dislocated to the rich side, a hydrogen quantity in the exhaust gas extremely increases. Thus, the abnormal air-fuel ratio variation among cylinders is detected by using this extreme increase. COPYRIGHT: (C)2009,JPO&INPIT
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