Method and engine brake system to control an engine brake of a vehicle

A method to control an engine brake of a vehicle, the vehicle being provided with a combustion engine having cylinders, an exhaust pressure governor (EPG) regulating the air flow out of the cylinders, an intake air throttle valve (ITV) regulating the air flow into the cylinders, and pressure sensing means for sensing a pressure downstream of the cylinders, the method comprising

• regulating an engine braking torque in a first engine braking mode (a), in which the air flow through the EPG is regulated by a closed loop control using the pressure downstream of the cylinders and the ITV is regulated in a feed forward control dependent of the engine speed and a demanded brake torque;
• regulating the engine braking torque in a second engine braking mode (b), in which the EPG is regulated in a feed forward control dependent of the engine speed and the demanded brake torque, and the ITV regulates the braking torque by a closed loop control using the pressure downstream of the cylinders;
• and
• determining which of the first and the second engine braking mode (a, b) should be used based on a demanded braking torque and an actual engine speed.