Method for operating an internal combustion engine having an auxiliary unit which can be selectively activated and deactivated

The internal combustion engine is especially a diesel engine and has a turbocharger and a supercharger with a belt drive from the engine. Throttle valves may control the distribution of the air supply to the engine. The control circuit may incorporate a torque coordination circuit (50) with inputs from the accelerator pedal (46) and a torque sensor (48). The control circuit produces signals (56) to control the air induction system, the fuel supply (52) and if necessary, the ignition system (54). Input signals for compressor speed etc. are received and a computation circuit (58) may send compressor drive torque signals (62) to the coordination circuit. A further circuit block (60) calculates a figure for the minimum air supply required.