The invention relates to a method for lambda adjustment and ignition angle adjustment of combustion in an internal combustion engine provided with at least one cylinder. The optimum air-fuel ratio or the optimum ignition angle is determined by the following features. The features can be used for determining an estimated value of torque and are based on analysis on the rotation speed of a crankshaft in the internal combustion engine. The invention also provides a corresponding device, especially an engine control unit provided with at least one adjusting unit and a storage unit to implement the method. As an adjusting parameter, the injected fuel amount or the ignition angle changes among different values from a next combustion circle to a directly or indirectly followed combustion circle, and changes of the features based on the rotation speed are analyzed to estimate the torque. By utilization of the method and the device, the efficiency or the maximum power is increased or discharge of harmful compounds is reduced, or a trade-off scheme for achieving all standards as good as possible can be obtained.