Internal combustion engine with device for warning of malfunction in an air-fuel ratio control system

摘要

A warning system for an air-fuel ratio control system for a electronic controlled internal combustion engine, where a basic fuel injection amount is corrected by a feedback correction factor determined by a signal from an air-fuel ratio sensor arranged in an exhaust pipe. An amplitude of the feedback correction factor caused by an acceleration of the engine, where the exhaust from cylinders is not completely mixed, is detected, and a warning can be given when the amplitude of the feedback correction factor is larger than a predetermined value. A malfunction in the air-fuel ratio system occurring in one cylinder can be detected. In a double O2 sensor system, where a sub-feedback loop is provided for correcting the feedback correction factor in accordance with a signal from the second O2 sensor, the sub-feedback is stopped when the amplitude of the feedback correction factor is larger than a predetermined value, and a quick and precise detection of a malfunction is obtained by stopping the sub-feedback operation.