The method involves tow-starting of an internal combustion engine (2) by using an electric motor designed as an initiator motor (3) that is coupled with the engine, where fuel is not supplied to the engine during tow-starting of the engine. An indication of power consumption of the electric motor is determined during tow-starting of the combustion engine, where the indication of power consumption of the electric motor corresponds to an indication of motor current of the electric motor. Torque loss of the combustion engine is adapted based on the determined power consumption. Independent claims are also included for the following: (1) a computing unit for adapting a torque loss of an internal combustion engine (2) an engine system (3) a computer program comprising a set of instructions to execute a method for adapting a torque loss of an internal combustion engine (4) a computer program product comprising a set of instructions to execute a method for adapting a torque loss of an internal combustion engine.