Combustible-gas sensor, diagnostic device for intake-oxygen concentration sensor, and air-fuel ratio control device for internal combustion engines

摘要

Correction of a fuel injection amount in an internal combustion engine during purge of evaporative fuel is performed on the basis of an output from an intake-oxygen concentration sensor disposed in an intake passage of the internal combustion engine. If the amplitude of fluctuations in engine speed becomes equal to or greater than a predetermined value, it is determined that there is an anomaly in engine output. In addition, if an anomaly in engine output is detected during purge and if no anomaly in engine output is detected during stoppage of purge, an ECU determines that an anomaly has occurred in the intake-oxygen concentration sensor, cancels correction of the fuel injection amount based on an output from the intake-oxygen concentration sensor during purge, and corrects the fuel injection amount on the basis of outputs from exhaust-gas air-fuel ratio sensors.