Lamminkäynnistykset

Lamminkäynnistykset refers to a phenomenon observed in certain internal combustion engines, particularly those found in agricultural machinery like tractors. It describes a situation where the engine, after being switched off, continues to run or "kick" for a short period before coming to a complete stop. This is distinct from the engine failing to start or stalling. The term itself is Finnish, directly translating to "sheep's starts," evoking the image of a hesitant or uneven engine operation.

The primary cause of Lamminkäynnistykset is typically pre-ignition or auto-ignition of the fuel-air mixture within the cylinders. This can occur when hot spots, such as carbon deposits or an overheated spark plug electrode, reach a temperature high enough to ignite the fuel charge before the spark plug fires. The heat and residual combustion pressure in the cylinder, even with the ignition system turned off, can then initiate a combustion event.

Factors contributing to Lamminkäynnistykset include engine overheating, excessive carbon buildup in the combustion chamber, incorrect ignition timing (though less relevant when the ignition is off), and the use of fuels with a lower octane rating than recommended, making them more prone to spontaneous combustion under heat. While often a minor annoyance, persistent Lamminkäynnistykset can indicate underlying engine issues that warrant inspection and repair to prevent potential engine damage.