Abstract: In order to alleviate sporadic shift shock when a transmission associated with a supercharged internal combustion engine undergoes an upshift while the engine is operating under minimal load (e.g. with the accelerator pedal non-depressed) the supercharge pressure is monitored and if the pressure is above a predetermined limit during a minimal load upshift, the pressure generated by the supercharging device is reduced and at the same time an idle control system feed-back meters the amount of air supplied to the engine so that the rate at which the engine speed reduces is maintained essentially constant irrespective of the initial supercharge pressure.