Cylinder speed variations in a combustion engine is an unwanted phenomenon caused by a number of different reasons. Inaccurate fuel delivery from the individual injectors, resonance frequencies in the drive train and faulty sensor readings are some probable causes. There is a need to investigate the potential of different cylinder balancing controllers in a simulation environment before implementing them in the ECU hardware. The thesis is about developing a simulation framework where different controllers can be tested. The framework will generate an engine speed signal based on injected fuel mass to the individual cylinders. A PI controller that makes individual fuel adjustments to the cylinders is implemented in the framework and tested for three different operating points and three different types of disturbances. The results show that the framework is able to generate an accurate engine speed signal based on the commanded fuel amount. Moreover the controller is able to eliminate imbalances caused by error in injected fuel mass as well as specific type of periodic load disturbances in the drive line. Some disturbances cannot be handled by the PI controller, as they lie outside of its controllable region. The simulation framework shows promising results and while further work is needed in some areas, it can work as a foundation for future development and controller evaluation.