A method of controlling fuel injection in an internal combustion engine is presented. For each injector event a drive signal is applied to the fuel injector, wherein said drive signal has a pulse width, which is calculated on the basis of a master performance function and of a minimum delivery pulse corresponding to the minimum pulse width required for the injector to open.The minimum delivery pulse is determined from the voltage across the terminals of the fuel injector's electromagnetic actuator, by comparing the duration of a segment of the voltage second derivative to a predetermined threshold value.