MEASURING METHOD FOR QUANTITY OF INTAKE AIR FOR ELECTRONICALLY CONTROLLED ENGINE

PURPOSE:To measure the quantity of intake air of a controllable engine smoothly by operating the quantity of air in accordance with the quantity of air measured with an air flowmeter provided in an intake passage and the quantity of air measured from the pressure in an intake pipe and the number of revolutions of the engine. CONSTITUTION:An air flowmeter 14 and an intake pressure sensor 22 are provided to the intake passage 12 of an engine 10, and the output thereof is inputted to a digital electronic control circuit 56 which controls a fuel injection rate 30, an ignition timing 34, a recirculation rate 52 for exhaust gas, etc. of the engine. The output of a crank angle sensor 40 provided to a distributor 36 is inputted to a control circuit 56. The circuit 56 operates the fuel injection rate, the ignition timing and the recirculation rate of exhaust gas by taking the quantity Q1 of intake air from the air flowmeter 13 as quantity Q of intake air when the Q1 is below the prescribed value and by determining the quantity Q2 of intake air from the sensors 22 and 40 when the Q1 is above the prescribed value and taking the product of the average value of the ratio between the previously measured Q'1 and Q'2 as the quantity Q of intake air, thereby controlling the engine easily.