| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an erroneous control determining device and an erroneous control determining method for an air-fuel ratio control system enabling an exhaust gas leakage and abnormality of a rear oxygen sensor to be accurately determined even if a sensor upstream of an exhaust purifying catalyst is abnormal. <P>SOLUTION: The device for determining erroneous control of the system for controlling an air-fuel ratio by estimating a catalyst state based on an output signal from the rear oxygen sensor provided downstream of the exhaust gas purifying catalyst and setting a shift correction value of air-fuel ratio control according to the estimated state to perform air-fuel ratio control, has a lean side staying rate ratio computing means for computing the ratio of a low load lean side staying rate to a high load lean side staying rate (step S3), and an exhaust gas leakage determining means for determining the erroneous correction of the air-fuel ratio control system caused by the exhaust gas leakage based on the lean side staying rate ratio before updating the shift correction value of air-fuel ratio control and the lean side staying rate ratio after updating (step S7). <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
