Idling speed ignition timing
When the idle speed control is active, the ignition is advance 10° before top dead center (BTDC).
Depending on the engine coolant temperature, idle speed control requests an idling speed.
If the current engine speed drops below the requested speed, such as when the power steering pump puts a load on the engine while the steering wheel is being turned, the ignition will be advanced by up to 10°.
This is done to increase the engine torque to compensate for the drop in engine speed. How much the ignition is advanced depends on how large the difference is between the current engine speed and the requested. The ignition is retarded in the same way when the current engine speed is higher than the requested.
The normal idle speed control that affects the throttle valve and thereby the air mass/combustion operates slower than the idle speed control based on the ignition timing.