| 摘要 |
PURPOSE:To suppress the deterioration of exhaust gas to the minimum by making the lead angle caused by the negative pressure ineffective irrespective of the manifold pressure and lagging the ignition timing when a throttle valve is closed or moved in the closing direction more than a predetermined degree. CONSTITUTION:During operation of an engine, a signal voltage produced from an ignition signal generator 1 is fed through a shaper circuit 2 to an ignition timing operating circuit 6 so as to perform the operation of a lead angle. An output signal of manifold negative pressure detected through a pressure sensor 1 is fed through an amplifier 4 to a function voltage circuit 5 so that the ignition timing is further led by means of said operating circuit 6 as the output voltage from said circuit 5 decreases. When the closure of the output from a comparator 15 is brought to L-level, a transistor 16 is turned on and the output voltage from the function voltage circuit 5 is increased so as to lag the ignition timing.
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