ACTIVATION DISCRIMINATING METHOD FOR EXHAUST COMPONENT CONCENTRATION DETECTOR IN INTERNAL COMBUSTION ENGINE

PURPOSE:To carry out certainly activation discrimination in operating condition, by leaning competently a real air-fuel ratio in slowdown operating condition, in response to the air-fuel ratio characteristic of an engine. CONSTITUTION:When a throttle valve 3' is closed, and an engine 1 is shifted from its normal operating condition to a prescribed slowdown operating condition, operation of the engine 1 is shifted from a feedback control range to an open loop control range. The correction coefficient available at this instance is held to the value of just before the shift until a prescribed time, passes after the shift, while the correction coefficient is set at the value 1.0 after a lapse of the prescribed time, so that the air-fuel ratio is leaned. Thereby, it is possible to lean the real air-fuel ratio in slowdown operating condition certainly and competently to the extent of prescribed amount, in response to the air-fuel ratio characteristic of the engine.