Patent attributes
In a system where an air-fuel ratio feedback correction amount is learned when its variation width is within a stable determination value, the stable determination value is set at larger value when a deviation amount of the correction amount becomes larger. When the air-fuel ratio feedback correction amount is rapidly changed after the learning is completed, the stable determination value is increased to moderate the learning condition and accelerate the learning speed (update speed of the learning value). Hence, the air-fuel ratio feedback correction amount is immediately learned. Furthermore, when a behavior of the air-fuel ratio feedback correction amount is stable, the stable determination value is made small to avoid an erroneous learning of the air-fuel ratio feedback correction amount.
