| 摘要 |
A target air amount for achieving a requested torque is back-calculated from the requested torque using a virtual air-fuel ratio. The virtual air-fuel ratio is changed from a first air-fuel ratio to a second air-fuel ratio in response to a condition for switching an operation mode being satisfied. After the virtual air-fuel ratio is changed, the target air-fuel ratio is maintained at the first air-fuel ratio until the ignition timing reaches a retardation limit. Subsequently, in response to the ignition timing reaching the retardation limit, the target air-fuel ratio is switched from the first air-fuel ratio to a third air-fuel ratio. After switching of the target air-fuel ratio, in response to a difference between the target air amount and an estimated air amount becoming equal to or less than a threshold value, the target air-fuel ratio is switched from the third air-fuel ratio to the second air-fuel ratio. |
