Have the oxygen sensor degradation decision device and this device the engine control unit and the display panel device

摘要

PURPOSE:To exchange an oxygen sensor before the deterioration thereof exerts adverse influ ence on the driving performance by determining the difference between the max. output value and min. output value of the oxygen sensor at every traveling of a vehicle for a pre scribed distance or determining the change rate in this difference, comparing the difference or change rate with a prescribed value and deciding the presence or absence of the deteriora tion. CONSTITUTION:The opening degree of a throttle valve increases to increase the suction air quantity and the basic pulse width increases so that a large volume of fuel is injected and supplied to the engine when an accelerator pedal is treated to accelerate the engine during the traveling of the vehicle. The fuel rich state is then attained and the output voltage value of the oxygen sensor 5 attains the max. value V2. On the other hand, the throttle valve is closed to decrease the suction air quantity and the basic pulse width Tp decreases as well when the engine is rapidly decelerated. The injection pulse width Ti usually fuel lean at the time of fuel supply stop and the output voltage of the sensor 5 attains the min. value V1. This difference V2-V1 decreases as the sensor 5 is deteriorated. The presence or absence of the deterioration is, therefore, decided by comparing this difference or the change rate thereof with the prescribed rate. The exchange of the oxygen sensor before the deterioration exerts adverse influence on the driving performance is possible.