An electronically controlled fuel injection control system for an automotive internal combustion engine equipped with a hot wire mass air flow sensor to detect an intake air flow amount. The fuel injection control system is comprised of a microcomputer adapted to control the amount of fuel to be injected from a fuel injector mainly in accordance with an engine speed and the intake air flow amount. In the control by the microcomputer, a compensation for time lag is applied onto an intermediate variable which is calculated from the intake air flow amount and used for calculating the fuel injection amount. During an engine starting time period from an engine starting to the time immediately after the engine starting, the compensation for time lag is prohibited until the engine speed has reached a predetermined level, thereby preventing engine control from becoming different between a case when the engine starting is made immediately after the instant of an electric power supply and another case when the engine starting is made upon waiting a little while after the engine starting.