Abstract: An engine control system has a heater and a temperature measuring element with a temperature-resistance characteristic. The heater and element are provided in the intake pipe of an engine. Heating, which initiated by a start pulse signal generated by an engine control unit in synchronism with engine rotation is supplied to the heater through a transistor. When the heater temperature has reached a reference temperature preset in accordance with the intake air temperature measured by the element, a comparator generates an output to deenergize the heater. The period of supplying the heating power is represented by a pulse signal from a flip-flop. This pulse signal is supplied as an airflow measurement signal to the engine control unit. The engine control unit calculates the basic fuel injection quantity and determines if the starting of the pulse signal received by the control unit falls within a predetermined period from the starting of the start pulse signal.