market dynamics
When does the spark plug need to be replaced?
Release date:2019.10.21

Spark plug normal life

Spark plug is a wearing part, which can be used for 1000h in general, equivalent to vehicle driving of 25,000km. That is, a vehicle traveling 25,000 km will have to replace the spark plug. If not replaced in time, will increase the burden of the entire ignition system, increase the discharge gap need higher voltage to jump fire, not only increased fuel consumption, but also to cause air pollution. Vehicle performance is difficult to accelerate, start, the engine easy to stall.

The time to replace the new spark plug is very important, because the new spark plug is the most economic and effective way to improve the performance of the engine, and the economic life of the spark is very different, the current market of motorcycle spark plug in the 3000-5000km.


Heavy carbon buildup on spark plugs

Air fuel ratio is too small, mixture is too thick, fuel and oil can not fully combustion deposit on the spark plug surface, or the use of inferior oil will produce carbon deposition; Ignition advance Angle too large, or deflagration and other abnormal combustion; The temperature of spark plug skirt is too low, that is to say, the thermal characteristics of spark plug is too cold and so on will produce carbon deposit.

Improper oil selection will seriously affect fuel mixing and combustion. Excessive C, Pb, Br, Cl and p in fuel oil, C, Ca, S, Ba and Zn in oil, and Fe, Si and Ai in mixed oil will affect the quality of oil.

Spark plug contact with gas. Generally speaking, the normal working temperature of the skirt is between 450℃ and 850℃. If the temperature of the skirt is lower than 450℃, the black carbon will be generated on the spark plug. Normal working spark plug has self-cleaning (clean) ability to carbon deposition, but long-term work is not normal, carbon deposition should not be removed, spark plug self-cleaning ability is powerless.

In this case, should first remove the cause of failure, replace the low calorific value spark plug, or carefully scrape off the accumulated carbon, adjust the gap after use. Serious carbon deposition will cause current leakage, weaken jumping spark, even can not jump fire, affect the operation of the vehicle. A bad burn can cause a vehicle to move feebly or even fail to run.

The pure black toner layer is a dry or wet layer of black toner deposited on the spark plug surface. This carbon powder layer is easy to cause short circuit of the insulator head, resulting in jump-off timing confusion and poor low-speed operation. The engine is easy to stall and start bad, etc.

The reasons are as follows

A) the selected spark plug is too cold;

B) long time low speed driving and long time idle speed;

C) the air-fuel ratio is too small and the mixture is too thick, which may be caused by the blockage of the air filter;

D) improper use of choke door;

E) ignition time is too late;

F) low jumping voltage (poor performance of ignition coil, loss of platinum, damage of collector or overpressure line).

Insulating ceramics have a shiny yellow layer

There is a shiny yellow fouling layer on the spark plug insulating ceramic due to the chemical reaction of lead compounds in the fuel when heated. This layer can easily cause the engine to stall during adjustment driving or climbing.

The fouling of lead compounds after sustained low speed driving, suddenly increase the throttle, the temperature in the cylinder suddenly increased will cause the fouling melt to form a smooth surface. The melt fouling layer is a good conductor of electricity at high temperatures, thus rendering the spark plug useless.

Since this coating is usually a hard and difficult to scrape off material, new spark plugs must be replaced. In order to prevent this pollution, less lead or unleaded gasoline should be selected.


The spark plugs are red, green, white and tan

The surface of the insulating ceramic and electrode of the spark plug is stained with red, green, white and brownish yellow material. The cleaning of this fault is relatively simple, generally speaking, this kind of fouling layer is not very thick, can be cleaned, scraping, readjustment gap can be used again.

This fault is caused by the compound impurities in gasoline and oil, or the incomplete combustion of tetraethyl lead in gasoline. At high temperatures, the film of the impurity will become conductive, causing a fire, causing the shutdown.

The electrodes are green and rough

Due to acid corrosion, the surface of electrode and insulating material is green and rough, and the spark plug with this kind of fault is easy to cause the engine to stall at high speed and high load.

Cause: due to the influence of gas temperature, the burning gas and lead compound produce acidic substances which cause corrosion to the electrode.

If acid corrosion is serious, spark plugs must be replaced.

Damp soiled layer

The spark plug surface forms a wet oil fouling layer. This fouling layer is a good conductor, often cause the engine to stall, especially at low speed performance and poor start performance.

The reasons for this failure are as follows

A) piston ring wear, cylinder wall wear and air leakage;

B) the temperature of the skirt is too low;

C) used piston rings are used on new engines or overhauled engines, so that they cannot be sealed effectively;

Remedial measures are as follows

A) temporarily change to a hotter spark plug. When it is confirmed that the piston ring is incapacitated, it should be abandoned and replaced with a new ring;

B) always pay attention to cleaning spark plugs until a new ring is replaced;