| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent emission deterioration etc., when an abnormal cylinder is specified. <P>SOLUTION: A plurality of cylinders of a multi-cylinder internal combustion engine includes: a catalyst; a temperature sensor for detecting a catalyst temperature; and a pre-catalyst sensor and a post-catalyst sensor which are air-fuel sensors of pre- and post-catalyst, respectively. On the basis of a detection value of the temperature sensor, the abnormal cylinder is specified when abnormality of air-fuel ratio variation between the cylinders in the plurality of cylinders is detected. When the abnormal cylinder is specified, main/auxiliary air-fuel ratio control based on output of the pre- and post-catalyst sensors is performed to the plurality of cylinders. On the basis of a convergence value of an auxiliary air-fuel ratio control amount ΔVrg based on the output of the post-catalyst sensor, the abnormal cylinder is specified. <P>COPYRIGHT: (C)2012,JPO&INPIT |
