| 摘要 |
PROBLEM TO BE SOLVED: To improve engine operability and exhaust performance by a method wherein purge of evaporated fuel is completed in the stoicky state of an engine, such as uniform stoicky and an empty purge state is held in a uniform and stratified leans state forming opening control of an air fuel ratio. SOLUTION: When it is decided at S4 that a lean operation permission condition is satisfied, it is decided at S5 whether a continuous lean operation time exceeds or is below a TMRLEAN (a restriction time of lean continuous operation). When it exceeds the TMRLEAN, advance to S6 is effected. Feedback control is made on a theoretical air-fuel ratio, advance to S10 is effected, and it is decided whether the purge condition of vapor is established or not. When OK, advance to S11 is effected. It is decided whether an air-fuel feedback correction factorαexceeds or below a time chart. Whenα, exceeds the time chart, advance to S12 is effected, a continuous lean operation time is cleared, and transfer to lean is permitted. Further, advance to S13 is effected, after computation of TRLEAM is computed, advance to S14 is effected and at S14, control DUTY of a purge control valve is computed.
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