In a device for adjusting the injection timing in a diesel engine fitted with EDC a basic value (SBGWs) of injection timing for operation in the static or steady state is stored in a first characteristic field (20) and a basic value (SBGWd) for operation in the dynamic or unsteady state (acceleration, deceleration) is stored in a second characteristic field (22). These basic values are dependent on desired injected fuel quantity (Q) and engine speed (n). The characteristic field (20) for the static state is designed empirically or otherwise to optimise fuel consumption whereas that (22) for the dynamic state is designed for minimum pollutant emission. A gradual changeover from one mode to the other is achieved by the gradual change of a multiplying factor (c) from 0 to 1 or vice versa responsively to dQ/dt departing significantly from zero or becoming zero.