| 摘要 |
PURPOSE:To compensate aged deterioration of an exhaust sensor, by changing a control constant in accordance with the ratio of time, in which an exhaust concentration detection value reaches from a rich side maximum value to a lean side minimum value, to the time in which the exhaust concentration detection value reaches from the lean side minimum value to the rich side maximum value, in the case of an air-fuel ratio feedback control. CONSTITUTION:An electronic control unit 5, which calculates the basic fuel injection on the basis of detection values from an intake absolute pressure sensor 8 and an engine speed sensor 10, compares a detection value of an O2 sensor 13 with the reference value performing a feedback control of air-fuel ratio by a proportional plus integral control. The electronic control unit 5 compares transfer mean time, in which the detection output of the O2 sensor 13 reaches from a rich side maximum value to a lean side minimum value, with the transfer mean time in which the detection output of the O2 sensor 13 reaches from the lean side minimum value to the rich side maximum value, and the control unit 5, detecting the displacement of the air-fuel ratio, changes a proportional constant and an integration constant in a direction of small decreasing this displacement.
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