AIR-FUEL RATIO CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE

摘要

PURPOSE:To prevent any fluctuation of a supply air-fuel ratio by maintaining a target air-fuel ratio at a value before gear shift during the gear shift and a predetermined time after the gear shift. CONSTITUTION:Air-fuel mixture supplied to an internal combustion engine 1 is feedback-controlled at a target air-fuel ratio according to an operating condition of the engine 1 by the use of an exhaust concentration sensor 15 disposed in an exhaust system of the engine 1 and provided with an output characteristic nearly in proportion to an exhaust gas concentration. It is detected whether or not a gear position of a transmission driven by the engine 1 is being shifted, and the target air-fuel ratio is maintained at a value before the gear shift during the gear shift and a predetermined time after the gear shift. Therefore, the target air-fuel ratio at the time of the gear shift can be suitably set so that fluctuation of a supply air-fuel ratio can be prevented.