Ignition timing adjustment

According to load condition (idle, part load, full load) and air quality, the fuel mixture burns from the combustion chambers at different speeds. In order to use the energy of the fuel most efficiently, the control unit changes the ignition timing depending on the load condition for each individual cylinder. The best time to ignite is when the air-fuel mixture ignites at the point of highest compression. In a four-stroke engine, this is the point at which the piston wants to go from forward on the compression stroke to reverse on the power stroke.

Ignition timing

Theoretically, the ideal moment of ignition is the moment at which the piston begins to move downwards, since the compression of the fuel mixture in the cylinder is maximum and the combustible fuel mixture acts on the piston with force. However, in practice, approximately 3 ms elapses between the initial moment of ignition of the fuel mixture and its complete combustion. Therefore, the formation of a spark should occur somewhat earlier than the piston reaches TDC, which will allow optimal combustion under all engine operating conditions, since the pressure from the combustion of the fuel mixture acts on the piston after it has passed TDC. So, the moment of ignition is transferred to an earlier period, called the ignition timing.