| 摘要 |
PURPOSE:To prevent occurrence of drastic torque change at the time of operating an engine on a highland, by providing a lean critical value setting means for setting a maximum value on the rich side of the air-fuel ratio and an output increasing control means for controlling the air-fuel ratio of the engine to keep it at the output air-fuel ratio. CONSTITUTION:A second air-fuel ratio calculating means calculates a second air- fuel ratio (A/F)2 richer than a first air-fuel ratio (A/F)1. When the opening of a throttle valve is equal to or greater than a first opening and smaller than a second opening (theta1<=theta<theta2), a second air-fuel ratio feedback control means feedback controls the air-fuel ratio to keep it at the second air-fuel ratio (A/F)2. A lean critical value setting means sets a maximum value at the second air-fuel ratio. Further, when the opening of the throttle valve is equal to or greater than the second opening (theta>=theta2), an output increasing control means controls the air- fuel ratio to keep it at the output air-fuel ratio. With such an arrangement, it is enabled to prevent occurrence of drastic torque change at the time of operating the engine on a highland.
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