Abstract: A method for sensing an air-fuel ratio of exhaust gasses from an engine of a vehicle using a sensor is provided. The method may comprise pumping a current in a pumping cell during; reducing said pumping during a set of operating conditions; and adjusting a fuel injection amount or an air amount into the engine to maintain a desired air-fuel ratio based on the sensor. In this way, a reference voltage can be driven by chemical reactions to equilibrate and provide an accurate indication of stoichiometry, similar to a HEGO sensor. Likewise, outside of stoichiometry, the reference voltage is controlled in a one-sided fashion via positive and negative pumping current at respective voltage limits to provide an indication of air-fuel ratio over a wide range.

Abstract: A method for sensing an air-fuel ratio of exhaust gasses from an engine of a vehicle using a sensor, the sensor having a pumping cell and a reference cell, the method comprising pumping a current in the pumping cell during at least a first set of operating conditions; reducing said pumping during at least a second set of operating conditions; providing a signal from the sensor during at least the first and second sets of operating conditions; and adjusting at least one of a fuel injection amount and an air amount into the engine to maintain a desired air-fuel ratio based on the signal during at least the first and second sets of operating conditions.

Abstract: An oxygen sensor for measuring exhaust gases of an internal combustion engine is described. The sensor provides an output that has a high gain near the stoichiometric air-fuel ratio, and a lower gain in the lean and rich air-fuel ratio regions. Further, the sensor provides wide range air-fuel ratio signal to be used in engine feedback control.

Abstract: A method of generating a shift schedule and combustion mode schedule to optimize performance characteristics of a lean capable, multiple combustion mode engine associated with a manual transmission with a time-variant after-treatment system is disclosed. The method comprises the steps of generating a lowest cost value for fuel economy and vehicle emissions as a function of an engine operating mode, wherein the engine operating mode is selected from a group consisting of a homogeneous stoichiometric mode, a homogeneous lean mode, and a stratified mode. The lowest cost value is stored in a shift schedule and combustion mode schedule along with the engine operating parameters that achieved the lowest cost value. Then, at a particular vehicle speed and wheel torque, the actual transmission gear is compared to the optimal transmission gear as determined by the shift schedule and combustion mode schedule.

Abstract: A diagnostic method for an internal combustion engine determines airflow using three independent airflow determinations. The three airflow determinations are compared to each other and an error is established if one airflow determination differs significantly from at least one other airflow determination.

Abstract: Fault detection in a feedback air/fuel ratio control system using an exhaust gas oxygen sensor compares the expected transport delay time to the time between exhaust gas oxygen sensor output level switching. A fuel system failure is determined when there is an inappropriate switching rate of the oxygen sensor output level.