for selectively enabling and inhibiting computation of successive new values of compensation factor based on this judgement application_number US 81930186 A description fig1 is a general block diagram for assistance in describing the basic features of the present invention in fig1 reference numeral 101 denotes actual phase difference sensing means for detecting a time difference which corresponds to an actual fuel injection timing of a fuel injection pump reference numeral 102 denotes operating condition sensing means for producing output signals that are input to target phase difference computation means 105 the target phase difference computation means 105 computes a target phase difference corresponding to a target fuel injection time compensation amount computation means 108 serves to compute a correction factor and tis factor together with the value of target phase difference and actual phase difference is applied to output value computation means 109 the output value computation means 109 computes an output value which is applied to control injection timing adjustment means 110 reference numeral 104 denotes correction factor updating feasibility judgement means for performing computations to judge whether the current operating condition of the diesel engine is suitable for performing updating of the correction factor with this updating computation being carried out on.