Patent ID: 7809490

Claim:
A fuel control system of an engine system, comprising: a pre-catalyst exhaust gas oxygen (EGO) sensor that determines a pre-catalyst EGO signal based on an oxygen concentration of an exhaust gas; and a control module that determines a dither signal, that determines a fuel command based on the pre-catalyst EGO signal and the dither signal, that determines a frequency of the pre-catalyst EGO signal, a duty cycle (DC) of the pre-catalyst EGO signal, a frequency of the dither signal, and a DC of the dither signal, that determines a frequency error based on the frequency of the pre-catalyst EGO signal and the frequency of the dither signal, that determines a DC error based on the DC of the pre-catalyst EGO signal and the DC of the dither signal, that determines a frequency correction factor based on the frequency error, that determines a DC correction factor based on the DC error, that determines a frequency of a compensated dither signal based on the frequency of the dither signal and the frequency correction factor, and that determines a DC of the compensated dither signal based on the DC of the dither signal and the DC correction factor when the frequency correction factor is greater than a predetermined value and the DC correction factor is within a predetermined range of values.