IGNITION TIMING CONTROL DEVICE FOR INTERNAL-COMBUSTION ENGINE

PURPOSE:To permit quick control conforming to an actual air-fuel ratio at all times and improve operating property, emission, fuel consumption or the like by a method wherein feedback control is effected so that the ignition timing is brought to the most proper value when the air-fuel ratio is deviated from a set value. CONSTITUTION:Data, showing a revolving speed N and a section pipe pressure P, are read from an RAM 56 while the value of an objective air-fuel ratio lambda1 and the value of the ignition timing theta'1, corresponding to the value of the objective air-fuel ratio, which are corresponding to one combination of the values N, P, are operated from a map. Subsequently, the actually measured air-fuel ratio lambda2 from a lean sensor 34 is read to operate the ignition timing theta'2 corresponding to the ratio lambda2 from the map and a difference DELTAtheta between the ignition timing theta'1 in the objective air-fuel ratio lambda1 and the ignition timing theta'2 in the actually measured value lambda2 is accommodated into the RAM56. The ignition timing compensating amount DELTAtheta+theta1 is operated as the ignition timing theta and a signal corresponding to theta is impressed on an output port 50. As a result, the ignition is effected at a crank angle corresponding to the ignition timing theta and the most proper controls of the operating property and the fuel consumption may be effected without delay.