A method of and a control unit arranged for controlling an internal combustion engine connected to a torque converter arranged to operate in a torque converter mode or a lock up mode are provided. The method includes determining whether the torque converter mode or the lock up mode is presently in operation and selecting to control an engine speed (N) in dependence of an operator input when the torque converter mode is present, and selecting to control an engine output power and/or engine output torque in dependence of operator input to the accelerator unit when the lock up mode is present.