| 摘要 |
PROBLEM TO BE SOLVED: To perform air-fuel ratio control corresponding to a degree of deterioration of a catalyst, by easily grasping the degree of deterioration of the catalyst by a simple constitution. SOLUTION: Based on a basic fuel injection pulse width Tp and a vehicle traveling distance D representing an engine load, a proportional component P and an integration component I of proportional plus integral control adjusting an air-fuel ratio feedback correction coefficientαby map reference are set (S14), and based on these proportional component P and integration component I, control converging the present air-fuel ratio to target air-fuel ratio is performed. Based on a vehicle traveling distance D secondarily representing a degree of deterioration of a catalyst, the proportional/integral component P, I in proportional plus integral control is variable set, so that reasonable good air-fuel ratio control performance can be easily realized till reaching to a life of the catalyst.
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