| 摘要 |
PROBLEM TO BE SOLVED: To provide an ignition timing control device for a spark ignition engine with a comparatively low engine speed and large size adopted to, for instance, a bus or a motor truck, which can attain stable driving while keeping the engine speed constant during idling, and hardly causes engine stall even under extremely low speed condition. SOLUTION: A spark advance rate of engine ignition timing. It is set constant when an engine speed Ne is lower than a control lower limit engine speed Na and decreased in accordance with increase of the engine speed Ne in the range of the engine speed between the control lower limit engine speed Na and a control upper limit engine speed Nb. Spark advance is performed so as to be restore to a reference ignition timing advancing characteristic in accordance with the increase of the engine speed, in the range of the engine speed between the control upper limit engine speed Nb and a reference characteristic restoring engine speed Nc and is performed in accordance with the reference ignition timing advancing characteristic when the engine speed exceeds the reference characteristic restoring engine speed Nc.
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