PURPOSE: To exactly perform the measurement of an oxygen sensor response time even in a wave form in which the output wave form of an oxygen sensor is converted into the digital with regard to the method. ;CONSTITUTION: A time TLEAN 1 of a time point T1 in which ADOX indicating an A/D conversion value of oxygen sensor output becomes a peak value of the lean side thereof to a time point T2 in which ADOX exceeds 0.45V in an increase process is counted to find. In addition, another time TLMIN*2 between the time point T1 and a time point T3 in which the succession of the peak value C of the lean side of ADOX is completed is counted to find. A value TLMIN which divides 2 into TLMIN*2 is subtracted from TLEAN 1 for the purpose of finding the response time TLEAN and the exact response time of the oxygen sensor can be stably found even from the wave form of the A/D conversion value.;COPYRIGHT: (C)1993,JPO&Japio
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