System and method for controlling the air / fuel ratio in an internal combustion engine

Abstract

A method and system are provided for adjusting an amount of fuel provided to an internal combustion engine based on an output signal from an exhaust gas oxygen sensor positioned downstream of an emission control device. The output signal from the exhaust gas oxygen sensor is compared to a set point reference value. The set point reference value is varied as a function of time, preferably according to a set point waveform that oscillates around an average set point. The average set point may either be a pre-determined constant or it may be determined based on at least one engine operating parameter. An electronic engine controller adjusts the amount of fuel provided to the engine based on the result of the comparison between the output signal of the exhaust gas oxygen sensor and the set point reference value.

Dependencies are inferred from the claim text.