Method of calibrating an actuator system for a variable nozzle of a turbocharger

A method for calibrating an actuator system for a turbocharger variable nozzle, the actuator system comprising an electronically controllable actuator coupled with a variable-geometry member of the nozzle and operable for causing movement thereof, and an electronic controller operable for controlling the actuator, the electronic controller having a memory for storing data. The method comprises (a) supplying a flow of fluid through the nozzle, (b) causing a continuous or stepwise movement of the actuator so as to move the variable-geometry member to cause a continuous or stepwise change in flow rate of the fluid through the nozzle, monitoring the changing flow rate, and recording at least two different points representing two different actuator positions and corresponding flow rates, and (c) storing in the memory of the electronic controller a multi-point calibration representing actuator position as a function of an input parameter designed to achieve a desired flow rate.