Carl R Squire

US Patent:

53577914, Oct 25, 1994

Filed:

Mar 15, 1993

Appl. No.:

8/031407

Inventors:

Thomas S. Gee - Canton MI
Thomas A. Schubert - Novi MI
Paul F. Smith - Dearborn Heights MI
Carl W. Squire - Taylor MI

Assignee:

Ford Motor Company - Dearborn MI

International Classification:

G01M 1500

US Classification:

731181

Abstract:

Functionality of the exhaust gas oxygen sensor is determined by continually monitoring the exhaust gas oxygen sensor voltage to determine both a peak rich voltage and peak lean voltage. Based on the information after some predetermined time period, a system determines whether rich air/fuel ratio excursions are required and lean air/fuel ratio excursions are required. If a rich air/fuel excursion is required, then there is a command to decrease the air/fuel ratio to make it rich until the peak rich voltage is greater than a predetermined threshold voltage. Analogously, if a lean excursion is required, then there is a command to have a lean air/fuel ratio excursion done until the peak lean voltage is less than a predetermined threshold. If a time out happened before the peak rich voltage was greater than the rich threshold or the peak lean voltage was less than the lean threshold, then there is a determination that there is a malfunction detected on the sensor/circuit.