PURPOSE: To prevent erroneous fuel injection by a method wherein in the method for calculating the fuel injection timing per cylinder group in response to a reference signal varying when the piston is near the upper dead center in its air intake stroke and a crank angle signal, the fuel is injected for all cylinders simultaneously in response to the crank angle signal when the engine is rotated at low speed.

CONSTITUTION: An electronic fuel injection controlling device operates such that in a control device 60, the basic fuel injection timing obtained from the outputs of an air flow meter 24 and a crank angle sensor 8 is corrected by the outputs of a sucked air temperature sensor 26 and an O2 sensor 44. Then a valve opening time signal is outputted to an injector 38 for each group of cylinders in synchronism with the fuel injection timing obtained from the reference signal for the output of the crank angle sensor 8 and the crank angle signal. In this case, when the engine speed is as low as, for example, less than 500r.p.m., the fuel is injected for all the cylinders simultaneously every time when a crank angle of 360° is reached, in response to the crank angle signal. Further, when the engine speed is as high as, for example, more than 4,000r.p.m., the fuel is injected for each cylinder group without group without discriminating the cylinders by the reference signal, in response to the crank angle signal.