Nippondenso Co., Ltd.

Katsunori Iwamoto

Ryosuke Tachi

Kiyotaka Sasaki

An apparatus for controlling the spark timing of an internal combustion engine comprises means for generating a reference position signal with reference to a predetermined engine crankshaft position; waveform shaping means for generating a reference pulse signal having a leading edge advanced with respect to the predetermined crankshaft position as a function of the engine speed, in accordance with the reference position signal; means for detecting the amount of engine load; means for detecting the rotational speed of engine; means for computing a period of time elapsed from the leading edge of the reference pulse in accordance with the detected engine load and engine speed in order to establish a spark timing; means for detecting the variation of period between the leading edge and trailing edge of the reference pulse in relation to each cylinder; and means for correcting the computed period of time in accordance with the detected variation and for generating an output signal causing ignition to occur after the elapse of corrected period of time. The computer estimate spark timing for each cylinder is corrected in accordance with the variation of a period between the leading edge and the trailing edge of the reference pulse, resulting in an optimum spark timing without variation among individual cylinders.

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Oobu, Japan

Katsunori Iwamoto