An internal combustion engine (10) has a control system (24) for processing various data to develop data for control of various aspects of engine operation, including controlling a device, such as an EGR valve (22) or turbocharger (16). A transient compensation strategy develops a multiplier data value for transient compensation of a control data value for controlling the device by multiplying that control data value by that multiplier data value. The transient compensation strategy comprises a map (34, 40) containing data values for the multiplier, each of which is correlated with both a particular data value for engine speed within a range of data values for engine speed (N) and a particular data value for accelerator pedal rate (APS_—d) within a range of data values for accelerator pedal rate. The strategy selects one of the multiplier data values from the map on the basis of a data value for engine speed and of a data value for accelerator pedal rate and then multiplies the control data value for controlling the device by the one selected multiplier data value.