| 摘要 |
PROBLEM TO BE SOLVED: To more surely restrain catalyst deterioration during fuel cut inhibit operation or fuel cut operation by starting fuel cut operation in the state of surely lowering the catalyst temperature in the course of fuel cut inhibit operation to a designated low temperature region in every internal combustion engine having variation in characteristic. SOLUTION: When a catalyst bed temperature TC exceeds a first temperature determination value T1, fuel cut from the point of time when a throttle opening TA is fully opened is inhibited and intake air is supplied through ISCV. The occurrence of misfire due to rich air-fuel mixture is prevented to promote lowering of the catalyst bed temperature TC. From the point of time when the catalyst bed temperature TC is below a second temperature determination value T2, the intake air supplied through the ISCV is gradually decreased, thereby gradually decreasing generation torque. According to oxygen concentration in exhaust emission detected by an O<SB>2</SB>sensor, the point of time when misfire starts to occur with development into rich air-fuel mixture is detected, and from this point of time, fuel cut is started. COPYRIGHT: (C)2004,JPO
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