| 摘要 |
PROBLEM TO BE SOLVED: To provide an air/fuel ratio control device of a multi-cylinder internal combustion engine, capable of equalizing the exhaust air/fuel ratio flowing into each catalyst converter by a single air/fuel ratio sensor without cost increase and properly implementing the air/fuel ratio feedback control when a plurality of catalyst converters are disposed parallel in a dual exhaust manifold system. SOLUTION: In this device, catalyst converters 24 and 26 are disposed parallel in a plurality of exhaust pathways 22a and 22b respectively disposed in each cylinder group (a group of cylinders #1 and #4 or a group of cylinders #2 and #3) of the dual exhaust manifold system. In the device, the feedback correction of the combustion air/fuel ratio is implemented based on the exhaust air/fuel ratio information from one exhaust sensor 29 disposed in a part 27 where the plural exhaust pathways meet. At that time, the irregularity of the exhaust air/fuel ratio between the exhaust pathways is detected based on the difference between the maximum value and the minimum value of the output of the exhaust sensor in a prescribed period of time, and the combustion air/fuel ratio is corrected and learned by each cylinder group whether the output of the exhaust sensor is the maximum value or the minimum value so that the irregularity of the exhaust air/fuel ratio is inhibited.
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