| 摘要 |
PROBLEM TO BE SOLVED: To prevent engine stall and an abnormal rise in idling speed due to malfunction even when a drop in a suction air amount not estimated normally in tolerance estimation occurs during idling operation. SOLUTION: When engine rotation speed is decreased to a low-rpm region (engine stall generating rpm region) where the possibility of engine stall exists during idling operation and an ISC learning value reaches an upper limit guard value, the cause is investigated. When the cause is determined to be due to lack of a suction air amount, as a result, the upper limit guard value is renewed to a suction air amount increasing direction. By so doing, the upper limit guard value to the ISC leaning value is normally set in a range of normal tolerance estimation from the viewpoint of fail safe. When a drop in a suction air amount not estimated normally in tolerance estimation occurs during the idling operation, the upper limit guard value is updated to a suction air amount increasing direction so as to be controlled to increase the suction air amount. COPYRIGHT: (C)2006,JPO&NCIPI
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