| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an initial failure detection method for a multi-cylinder internal combustion engine which detects initial failure of the multi-cylinder internal combustion engine from a viewpoint of whether an inter-cylinder imbalance ratio is unusual while considering variations of output values of a gas sensor. <P>SOLUTION: On the basis of output values of the gas sensor arranged in an exhaust passage of the multi-cylinder internal combustion engine, initial failure of the multi-cylinder internal combustion engine at manufacturing inspection is detected as follows. An amplitude of an output value of the gas sensor is acquired in each of a plurality of conditions in which the inter-cylinder imbalance ratios vary (S30, S60). On the basis of the plurality of amplitudes, a ratio of change in the amplitude of the output value of the gas sensor to change in the inter-cylinder imbalance ratio is calculated (S70). A case where the inter-cylinder imbalance ratio is determined to be larger than a reference threshold based on at least one amplitude and the calculated ratio of change is detected as a case where the internal combustion engine has initial failure (S110: YES). <P>COPYRIGHT: (C)2012,JPO&INPIT |
