| 摘要 |
<p>PURPOSE:To improve accuracy of air-fuel ratio control in each cylinder without variation by independently updating a learning value for correcting a reference control value so as to approach a target value based on a feedback correction rate corresponding to a reference control rate of an air-fuel ratio. CONSTITUTION:Air-fuel ratio feedback control is executed in each cylinder based on first and second air-fuel ratio detection means (sensors) 14, 15 of upstream side exhaust passages 8, 9. Phase difference of control values is generated between the cylinders, and it is detected by a control phase detection means. A control constant correction means performs correction so as to eliminate the phase difference through correction of frequency control by correcting a control constant which is adjustable in control frequency in air-fuel feedback control of non-reference cylinders based on the phase difference. At the same time, an air-fuel ratio leaning means executes air-fuel feedback control while correcting the control constant of the non-reference cylinders based on the phase difference with an air-fuel ratio detection value of reference cylinders being a base. And it updates a learning value in each cylinder for correcting the reference control rate so as to approach the target value.</p> |
