| 摘要 |
An apparatus according to the present invention includes a control apparatus to detect an inter-cylinder air-fuel ratio variation abnormality based on an output fluctuation parameter correlated with a degree of variation in output from an air-fuel ratio sensor. The control apparatus is configured to calculate a positive slope value and a negative slope value when the output from the air-fuel ratio sensor changes to lean side and to a rich side; calculate a determination index value by dividing a difference or a ratio between the positive slope value and the negative slope value by an amplitude index value correlated with a magnitude of a maximum amplitude of the output waveform from the air-fuel ratio sensor; and determine whether a deviation of the air-fuel ratio in one cylinder is a lean-side deviation or a rich-side deviation, based on the determination index value. |
