PURPOSE: To prevent occurrence of erroneous control that is possibly caused at the time when the temperature of exhaust gas is raised extraordinarily, by stopping feedback control of the air-fuel ratio in case that the minimum value of output voltage of a resistance varied type sensor for detecting the density of exhaust gas is higher than a predetermined limit value.
CONSTITUTION: An output voltage Vox obtained through A/D conversion of the output voltage of an O2-sensor 10 is given as an input to a CPU32, which calculates the minimum value Vmin of the output voltage Vox. In case that it is judged that air-fuel mixture is lean, the minimum value Vmin of the output voltage Vox is compared with the upper limit value E, and if Vmin is greater than E, the CPU32 stops feedback control of the air-fuel ratio. Resultantly, variable temperature range of the sensor 10 for detecting the density of O2 can be detected correctly and accurately, so that it is enabled to prevent occurrence of erroneous control that is possibly caused at the time when the temperature of exhaust gas is raised extraordinarilly and therefore to control the air-fuel ratio correctly.
YAEGASHI TAKEHISA
NAKAJIYOU YOSHIKI
| JPS54151730A | 1979-11-29 | |||
| JPS51129530A | 1976-11-11 | |||
| JPS5382928A | 1978-07-21 |
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