Engine output controller

The invention relates generally to control systems for internal combustion engines, and more particularly, concerns a powertrain controller for drive by wire vehicles. An engine output control method for a vehicle having a drive by wire engine system responsive to a desired engine speed signal. The method comprises the steps of generating a driver demanded engine speed value corresponding to an operator input and generating a speed control system engine speed value corresponding to a predetermined speed value to permit vehicle operation at a constant speed by a speed control system. The method arbitrates between the driver demanded engine speed value and the speed control system engine speed value to derive a first desired engine speed value. This value is limited by a vehicle speed limit value, engine speed limit value, and transmission speed limit value to generate a second desired engine speed value. The engine is then controlled as a function of the second desired engine speed value and an actual engine speed value. In another aspect of the invention, a traction control value and transmission limiting value are generated in the torque domain and arbitrated against the speed domain-based second desired engine speed value to control the engine output. In another embodiment, the driver demand, speed control and traction control are arbitrated in the vehicle or engine acceleration domain and constrained by engine, transmission and vehicle speed limits.