What is low speed early ignition?

With the increasing number of gasoline vehicles using direct injection technology, the problem of low speed early ignition (LSPI) has been gradually paid attention to. It is a specific problem of gasoline direct injection engines, is an unexpected gasoline spontaneous combustion phenomenon that occurs before the spark plug ignition, if it occurs continuously, it is likely to lead to engine failure.

Contemporary four-stroke gasoline engines have a "suction burst" four strokes, and during the suction stroke, the high-pressure nozzle of the direct injection system will spray atomized gasoline diagonally onto its opposite cylinder wall. The atomized gasoline was supposed to wait for the spark plug to ignite, but instead, some of the gasoline combined with the oil film on the cylinder wall and liquefied to form a gasoline oil mixture. During the next compression stroke, this mixture is scraped into droplets by the upward piston, and as the piston gradually approaches TDC, the high-temperature and high-pressure conditions will gradually form in the combustion chamber for the gasoline oil mixture to spontaneously ignite. Eventually, the gasoline oil mixture spontaneously ignited and exploded before the spark plug ignited, which is "low-speed early ignition."

After the low-speed early ignition occurs, the remaining oil and gas mixture is then ignited by the spark plug according to the normal process, so that the two explosions on the piston bear more pressure, and the engine will also appear with the "knock" phenomenon of metal knocking. Over time, the overwhelmed piston will gradually crack, or even break, and cause serious damage to the engine.

In order to cope with low-speed early combustion, many lubricant manufacturers have developed a new oil formula, which can avoid the reaction and spontaneous combustion of atomized gasoline and oil from the source, so as to achieve the function of avoiding low-speed early combustion from the source. If your car's engine uses direct injection technology, and you often encounter engine knock in the process of daily use of the car, you can pay more attention to products with low-speed early ignition formula when choosing oil.