Gm Global Technolgoy Operations, Inc.

Norman Maasshoff

Marc Bryan Center

Aparicio J Gomez

Oxygen sensor temperature and switching frequency compensation is provided to engine air-fuel ratio control, wherein the drift in the sensor voltage corresponding to stoichiometry is modeled and accounted for in the control, providing improved accuracy in conventional closed-loop engine air-fuel ratio control.

Closed-loop air-fuel ratio controller

A circuit inserted between a microprocessor controller and a stepper motor driver uses a detector to detect single peak or double peak pulses from the controller and selectively produce one or two motor steps for each controller program loop, and a time delay circuit to regulate the time of the second step to yield a substantially regular stepping rate.

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Warren, MI, United States of America

Norman Maasshoff