| 摘要 |
PROBLEM TO BE SOLVED: To restrain the ignition caused by an increase in fuel due to asynchronous injection in a spark ignition engine 1 conducting asynchronous injection for increasing fuel in addition to synchronous injection per revolution when idling is switched to acceleration. SOLUTION: When the engine 1 idles after being warmed up and the temperature of intake air is low, an EGR valve 25 closes, and the air-fuel ratio of mixture is controlled so as to become a nearly theoretical air-fuel ratio by controlling the opening of an ISC control valve 19 and fuel injection quantity (SB2 to SB4). When the temperature of intake air is medium, the EGR valve 25 opens ad the air-fuel ratio of the mixture is nearly theoretical air-fuel ratio (SB6 to SB8). When the temperature of intake air is high, the EGR valve 25 opens and the ISC valve 19 is also relatively large for controlling the air-fuel ratio of intake air so as to become a specified value that is lean more than a theoretical air-fuel ratio.
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