AIR-FUEL RATIO CONTROL IN INTERNAL-COMBUSTION ENGINE

PURPOSE:To obtain the always optimum air-fuel ratio by rewriting the contents of the memory into which the control value of the amount of the supplied fuel corresponding to the output value of an O2 sensor is written-in in rewriteable ways, at each rewriting time which is variably set in proportion to the number of engine revolution. CONSTITUTION:An O2 sensor 9 for detecting the air-fuel ratio from the O2 concentration in exhaust gas is installed into an exhaust manifold 7, and when the detected air-fuel ratio is less than a theoretical air-fuel ratio, a rich signal is outputted, and in the reverse case, a lean signal is outputted. A fuel injection amount calculated in an EPU11 on the basis of the ignition signal of a distributor 10 is properly corrected and controlled. Though the correction control is carried-out by using the memory into which the control value of the fuel injection amount corresponding to the output value of the O2 sensor 9 is written-in in rewriteable ways, the contents of the memory is rewritten at each rewriting time which is variably set in proportion to the number of engine revolution.