PURPOSE: To control a span of ignition timing in an optimum manner by selecting such data as capable of setting the ignition timing of a lower limit, where a timing advance value to be operated becomes yet smaller, alternatively from plural lower limit ignition timing data in the case where this lower limit ignition timing is compensated for timing advance control as it is so judged as a driving state being apt to produce a knocking.
CONSTITUTION: An electronic control unit 20 controls an injector 12 and an igniter 14 of an internal combustion engine 2 respectively on the basis to each detecting signal of two detecting means 8 and 18 detecting each of driving states in this engine 2, in addition to a knock sensor 10. In brief, in such a driving state that a knocking is hard to occur, fundamental ignition timing is compensated on the basis of timing advance value out of the fatal ignition timing. On the other hand, in the driving state being liable to produce a knocking, lower limit ignition timing is compensated on the basis of the timing advance value out of this lower limit ignition timing. In this case, in a central processing unit 22 of the electronic control unit 20, data for setting the lower limit ignition timing are alternatively selected from those of lower limit ignition data stored in a read-only memory 24 so as to make the timing advance value to be operated become yet smaller.
HOTTA MINORU
TAJIMA SHIGEHIKO
