When the engine speed during idling has fluctuated from the target idle speed, the ECM adjusts the ignition timing to stabilize the engine speed. The ECM is constantly calculating the average engine speed. If the engine speed falls below the target speed, the ECM advances the ignition timing by a predetermined angle. If the engine speed rises above the target speed, the ECM retards the ignition timing by a predetermined angle.
This correction is not executed when the engine exceeds a predetermined speed.
In some engine models, the advance angle changes depending on whether the air conditioner is on or off. In other engine models, this correction only operates when the engine speed is below the target engine speed.
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