1. In a method of controlling an internal combustion engine turbocharger which includes a volute passage through which exhaust gases flow from an internal combustion engine associated with said turbocharger and means for throttling said passage in a manner to vary the supercharging capacity of said turbocharger, the steps of: (a) sensing a first engine operational parameter; (b) sensing a second engine operational parameter which varies with the supercharging of said engine; (c) generating a control signal S.sub.DM for controlling said throttling means in response to the magnitude of said first parameter; (d) modifying said control signal in response to the magnitude of said second parameter; (e) sensing the demand for engine acceleration; (f) modifying said control signal in response to said demand for acceleration in a manner to cause said throttling means to increase the throttling of said passage to at least a predetermined degree until a predetermined event occurs; (g) modifying said control signal in response to the occurrence of said event until said event terminates; (h) maintaining, in the absence of said event, the modification of said control signal derived in step (f) for a predetermined period of time; and (i) varying said predetermined period of time in response to a selected operational parameter.