| 摘要 |
PROBLEM TO BE SOLVED: To attain improvement of exhaust emission by enhancing a control follow up property with a skip amount of an air/fuel ratio feedback correction coefficient set as an optimum value in accordance with an operating condition. SOLUTION: When an integrated valueΣTp of a basic fuel injection pulse width Tp as an engine load exceeds a preset value, a fixed amount of exhaust gas passes through in a catalyst, to be considered update timing of a rear air/ fuel ratio correction amount PHOS, the rear air/fuel ratio correction amount PHOS in the preceding time, in accordance with whether an output of an RO2 sensor is in a lean or rich side, is adjusted by a proportional component PPHOS and an integration component. In this way, a fixed amount of exhaust gas passes through in the catalyst, timing of an output changing of a second air/fuel ratio sensor is caught, a skip amount can be properly adjusted, when an air/fuel ratio feedback correction coefficient is clamped, even when it is large changed in one direction to lengthen a control period, a control follow up property of air/fuel ratio feedback control is enhanced, exhaust emission can be improved.
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