Air-fuel ratio control system for internal combustion engine

摘要

In an air-fuel ratio control system for an internal combustion engine, a fuel injection amount to be injected from a fuel injector is set based on a monitored operating condition of the engine. The fuel injector injects a corresponding amount of fuel to the engine. An air-fuel ratio sensor monitors exhaust gas discharged from the engine and detects an air-fuel ratio. The system derives an injector sensitivity based on a current fuel injection amount and an output of the air-fuel ratio sensor and further derives, as an injector sensitivity deviation, a ratio between the derived injector sensitivity and an injector sensitivity estimated upon designing the system. The system further derives a sensitivity correction term based on the derived injector sensitivity deviation so as to correct the injector sensitivity. The system may also correct an air-fuel ratio sensor sensitivity in a similar manner.