| 摘要 |
PURPOSE:To detect certainly deterioration of an oxygen sensor without any misjudgement by measuring a necessary time for repetitive inversion of the output of an oxygen sensor between rich condition and lean condition, and judging deterioration of the oxygen sensor when the average value of measured values is outside a set rang. CONSTITUTION:In a microcomputer unit 3, an injector 1 provide in an intake pipe 4 is controlled on the basis of a detected signal outputted from an oxygen sensor 2 or the like which is provided upstream from the Manivertor 5 of an engine. In this case, in the microcomputer 3, feed back control is stopped temporarily during feed back control at the time of normal operation, and open loop control for sweeping an air fuel ratio is carried out so as to forcable amplify output of the oxygen sensor 2. A necessary time for repetitive inversion of the output of the oxygen sensor 2 between rich condition and lean condition is measured, while deterioration of the oxygen sensor 2 is judged when the average value of measured values is outside a set range. |
