Method for Fuel Injector Characterization

A method of operating a fuel injection system for a motor vehicle includes one or more of the following: operating a fuel injector to perform a fuel injection, the fuel injector being in fluid communication with a fuel rail; sampling a rail pressure in the fuel rail during the fuel injection; regulating the rail pressure at a desired injection pressure, P, to the fuel injector; measuring an overall leakage on variations of the rail pressure across an engine cycle for the motor vehicle and between two engine positions of an internal combustion engine for the motor vehicle; and restarting a new measurement cycle for a new pressure measurement target.