Method of determining injection parameters for an injector

A method of determining a minimum drive pulse (MDP) for an injector (7) in a fuel system (1) within an engine, the injector being associated with a source of pressurised fuel (4), the method comprising: (a) sending a drive pulse of a first length to the injector; (b) determining an expected pressure in the fuel system at a given time; (c) measuring an actual pressure in the fuel system at the given time; (d) determining if an injection event has occurred by comparing the expected and actual values; (e) repeating steps (a) to (d) with drive pulses of progressively increasing lengths until an injection event has occurred and setting the drive pulse length associated with the injection event as the MDP of the injector.