| 摘要 |
PURPOSE:To correct the discrepancy between air-fuel ratios which change with an elapsed time, by comparing the average outputs of O2 during a prescribed time under a same condition with its previous value at each prescribed travelling time, judging it to be the deterioration of an O2 sensor when the difference is more than a prescribed value, and setting up input shift values corresponding to the deterioration. CONSTITUTION:A timer 17 is set up at each prescribed travelling time on condition that more than a prescribed time is passed away after the starting of an engine and water temperature is more than a prescribed value, by means of the logical multiply of the outputs of a water temperature switch 2 and a timer 15 which is set up when an ignition switch 1 is put on. The timer 17 calculates the average output VB of an O2 sensor 3 from an O2 detecting portion 11 via a calculating means 12 for a prescribed time, and a deterioration judging means 13 compares it with previous average output VA. When the difference between the average value of this time and the average value of the previous time is more than a prescribed value, a correcting means 18 reads out input shift values corresponding to the average output from a memory portion 19, and outputs the input shift values to an air-fuel ratio feedback controlling means 20.
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