At the top of the engine cylinder, there are three small partners, they are: fuel injector, intake valve, spark plug.

The intake valve is responsible for letting in the air, the fuel injector is responsible for injecting the gasoline, and the spark plug is responsible for the "ignition" in the middle.

Spark plug ignition, 4 stages

1. The ignition coil generates high-voltage electricity at both ends of the spark plug electrode, and the medium between the high-voltage breakdown electrodes generates electric sparks.

2. After the mixture is heated by the high temperature of the arc, the flame core is produced.

3. If the flame core becomes larger, the electrode structure of spark plug will affect this process, thus affecting the ignition performance of spark plug.

4. The mixture is ignited when the core temperature of the flame rises to the ignition point of the mixture.

The job of spark plug turned out to be a high-risk and busy job! Every two revolutions of four stroke engine, spark plug ignites once, that is: when the engine speed is 800r/min spark plug ignites 6.67 times in one second; when the engine speed is 2000r/min spark plug ignites 16.67 times in one second; when the engine speed is 5000r/min spark plug ignites 41.67 times in one second.

Normal state of spark plug

Generally, there is one spark plug in each cylinder of a gasoline engine, and two spark plugs are installed on individual engines, but these two spark plugs are not ignited at the same time. Generally, one is ignited when the TDC is compressed, and the other is ignited when the exhaust is finished, which can effectively reduce the engine emissions.

The normal state of the spark plug is: the insulator skirt is gray white, gray yellow, or light brown, indicating that the engine is normal and the heat value of the spark plug is normal.

Effect of carbon deposition on spark plug

Carbon deposition is an organic compound. It is an insulator and does not conduct electricity. When there is carbon deposit on the spark plug, an insulating layer will be formed on the electrode of the spark plug, which increases the difficulty of high-voltage electric breakdown of the medium between the electrodes. The ignition voltage will increase, which will reduce the success rate of ignition. Even if there is serious carbon deposit, the engine will not start.

How to remove carbon from spark plug?

In general, the spark plug needs to be replaced in case of serious carbon deposition. If it's not serious, remove the carbon deposit on the spark plug and then use it.

White vinegar soaking: according to the severity of carbon deposition, the soaking time of spark plug is determined. Generally, it can be soaked for 3-5 hours. Take out the spark plug and brush the spark plug with a soft brush such as a toothbrush. The carbon deposition on the plug is easy to fall off.

I'd like to remind you that when you operate, you should not immerse the whole spark plug in white vinegar, which will corrode the external surface of the spark plug, make it lose luster and reduce the anti-corrosion ability; in addition, you should not brush the electrode of the spark plug with an iron brush, which will make the electrode of the spark plug uneven and increase the consumption of the spark plug.