| 摘要 |
PROBLEM TO BE SOLVED: To quickly converge an air-fuel ratio on a target air-fuel ratio by securing a feedback correcting quantity sufficient enough for necessity, even in time of the air-fuel ratio being suddenly changed by a concentration variation of fuel vapor flowing into an inlet pipe from a fuel tank, after the elapse of the specified time from the time of valve opening operation in a purge control valve. SOLUTION: When elapsed time from the time of valve opening operation in a purge control valve 17 is long and a purge flow rate is largely changed according to the change of an intake air quantity and thereby an air-fuel ratio is suddenly varied, a feedback correcting quantity is calculated on the basis of a variation rate in the purge flow rate with the change of the intake air quantity, and the larger in the variation of the air-fuel ratio, the more the feedback correction quantity is increased. Therefore, during the feedback control over a fuel injection quantity, the air-fuel ratio can be quickly converged on the target air-fuel ratio, so that the worsening of emission is prevented.
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