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Whether you sell auto parts or repair cars: spark plug parameters daquan to send you a!
Release date:2019.05.27

As the car is becoming more and more high, the configuration of the engine power output, the spark plug ignition requirements also more and more high, to improve the efficiency of the spark plug ignition, the designers chose to substantially increase the ignition voltage to earlier santana only ignition voltage 18000 v, and now most of the intermediate car has reached to 30000 v, some high-end cars is even higher.


Of various parameters on the ignition performance of the spark plug is particularly important, once small spark plug general time has in the past, as can be seen from the market feedback information, car maintenance application and installation technology of the spark plug on the not enough attention, frequent replacement of automobile engine jitter, smoke after the spark plug, underpowered, leakage, or even spark plug break in cylinder or DingGang phenomenon, even if the owner complain, and make oneself is expected to take work also lost the trust of the customers.

Here, I will list the various parameters of spark plug one by one, and explain its importance, I hope to help you better understand the spark plug, help you make a correct judgment, reduce the spark plug caused by customer complaints.


Flower plug calorific value, popular expression is the fire flower plug skirt body

The temperature (around the central electrode) is usually expressed in Arabic numerals. For example, the number 8 in the Bosch number F8DCOR, it should be noted that this "8" does not refer to 8 degrees, but to a temperature range value indicated by "8".

Because gasoline cannot be completely burned in the engine, there will be a small amount of carbon powder deposited on the central electrode and side electrode of the spark plug, which will accumulate to a certain extent and seriously affect the normal work of the spark plug. However, if the temperature of the spark plug is high enough, the carbon powder will burn itself. We call the temperature range of the combustion of the carbon powder as the suitable spark plug calorific value of the engine.

What determines the calorific value of a spark plug is its structure. The skirt is a very important term for a spark plug, and the area of the skirt in contact with the air determines the calorific value of the spark plug.


As shown in the figure above, the larger the area of contact between the skirt and air, the better the heat dissipation of the spark plug, and the lower the temperature of the spark plug itself, that is, the lower the calorific value of the spark plug. On the contrary, the smaller the contact area between the spark plug skirt and the air, the worse the heat dissipation of the spark plug, and the higher the temperature of the spark plug itself, that is, the higher the calorific value of the spark plug.

It should be noted that the number of championship and Bosch spark plug is the smaller the calorific value is higher, NGK and denso is the number of the larger calorific value is higher.

The spark plug resistor is designed to reduce the magnetic interference caused by the high voltage of the ignition circuit.


General spark plug resistance is divided into zero resistance (for carburetor engine), one thousand ohm resistance (with a lower electric injection model), five thousand ohm resistance (electric injection engine).

Most of today's models use a 5, 000 ohm spark plug, and very few use a 1, 000 ohm spark plug (the old jetta, santana superman, etc.). Where, with the specifications of different levels of spark plug interchange, can use a large resistance instead of a small resistance, and can not use a small resistance instead of a large resistance. Any brand of platinum and iridium spark plugs is bound to be highly resistant.

In spark plug Numbers it is common to use "R" for resistance. At present, Bosch spark plug has the largest market share in the 1000ohm resistance spark plug market. The resistance number of Bosch spark plug is as follows: "R" represents the resistance of 1000 ohms after the digital calorific value, and 5,000 ohms before the digital calorific value. For example, F8DCOR has a resistance of 1000 ohms; FR8DPX is the resistance of 5000 ohms.


Spark plug gap refers to the distance between the side electrode and the center electrode.

The clearance required by different engines varies from 0.6mm to 1.6mm, which is determined by the high voltage redundancy generated by the ignition coil.

Generally, the larger the gap and the longer the arc, the greater the ignition energy. But if beyond the redundancy, ignition coil, will have its reverse, not only can not improve the ignition energy of spark plugs, but due to lack of voltage cause spark plugs fire, at the same time, the overload operation of the ignition coil due to long time, cause excessive load on the ignition coil and fever, make internal short circuit or open circuit is damaged, most of the ignition coil design life is more than 300000 kilometers, incorrect use of spark plug, make its early retirement, is a major cause of many repair shop ignition coil return.

However, too small spark plug clearance is not good, can not fully apply high voltage, ignite the mixture of heat is not enough, resulting in incomplete combustion, so that the engine power can not be fully released. Under normal circumstances, the life of the spark plug is determined by the spark plug gap, too large gap need breakdown voltage is too large, ignition coil voltage redundancy is not enough, but will make insufficient ignition.

Above all, real life refers to the economic life of the spark plug, spark plug, rather than its service life, from our many years of experience in management of the product, the economic life of general single electrode spark plug is about 40000 km (regardless of the spark plug material, is to be noted in the market for platinum, iridium spark plug some manufacturers mentioned that the service life of the hundreds of kilometers, when we use the result is more than 30000 kilometers in power decreases obviously, the center electrode also has apparent consumption, clearance, may use hundreds of kilometers ignition there is no problem, whether the economy, this debate. However, because the electrodes of the iridium and platinum spark plugs can be made very thin, the ignition energy at the beginning of use is indeed stronger than that of ordinary spark plugs.


The thread length of spark plug determines the best position of spark plug ignition and is an unchangeable parameter in the application of spark plug.

Generally, it is divided into 12.7mm, 19mm(small square spark plug) and 26.5mm (long thread type, crown rui zhi, etc.). It should be noted that new employees should be careful when installing the spark plug with long thread. It is not allowed to install the spark plug with long thread on the model with short thread.

One example: the Elysee 8 v model 19 mm length of spark plugs, and 16 v models installed 26.5 mm, a repair shop to the Elysee new employees from materials acquisition spark plugs, because the Elysee 16 v's far more than 8 v, material is provided by the 16 v, the worker because of lack of experience, directly installed does not match the spark plug, cause the engine valve DingGang, causing unnecessary loss to the enterprise.

A spark plug that burns normally

The spark plug insulator skirt is brown or off-white, indicating that the spark plug burns normally and matches the engine.

Overheated spark plug: the insulator skirt is cauterized and the electrode is ablated prematurely.

The reason for this is that the ignition time is too early, fuel injection is too late, resulting in poor cooling conditions; It is also possible that low octane gasoline was used, the mixture was too thin, the spark plug did not match the ignition position in the cylinder and the ignition value of the spark plug was too high. The solution is to replace the spark plug with a lower calorific value.

Spark plugs with manganese lead poisoning


The insulator skirt and the electrode are fused.

The cause is the addition of high melting point oxides containing manganese, lead and other elements to gasoline.

When continuous speeding cars, these lead manganese oxide is not spark plug skirt body temperature in cylinder decomposition, but will deposit on the spark plug, such as manganese, lead oxide of poor heat conductivity, jet fuel can reduce the temperature, and auto continuous high speed make these oxide gathering energy, temperature is far beyond the melting point of the spark plug electrode materials, melt the spark plug electrode and failure, often appear in high-speed long after, this kind of phenomenon does not belong to the quality problem of the spark plug, education should be the owner to avoid inferior gasoline additives at will.

Carbon spark plugs


As shown in the figure, the spark plug with black fluff carbon deposition is an abnormal phenomenon.

There are a variety of causes leading to carbon deposition, such as air filter for a long time did not replace or use inferior products, so that the intake of air is not enough, fuel is not fully combustion; Secondly, the calorific value of spark plug itself is too low to have self-cleaning ability. There is also the throttle body is too dirty, blocking opening, resulting in insufficient air intake, fuel is not fully combustion. For spark plugs, replace the spark plug with a higher calorific value.


Arcing spark plug

A common phenomenon of spark plug is the leakage of ceramic body, namely the phenomenon of flashover.

There are two main reasons for this phenomenon:

1, high-voltage wire aging and hardening, its insulation performance decreased, high-voltage wire and spark plug gap, the impurities in the air is high pressure generated by the magnetic field magnetization, in this gap into a conductive body, resulting in high voltage leakage;

2, associated with the installation of maintenance workers, the general situation, should try to avoid hand contact with the spark plug of ceramic body, especially in the summer, have sweat, and sweat contains sodium chloride, belong to the ionic compound, is a strong electrolyte, if in the humid air, and in the role of tens of thousands of volts of high voltage, the arc trace sweat residue enough to become a conductor, the breakdown of the spark plug ceramic body, the spark plug failure.

Spark plug corona phenomenon

Spark plug insulator near the screw cap has a layer of brown scale, many car owners mistakenly believe that the spark plug leakage, in fact, this phenomenon is not leakage, not to say that the quality of spark plug problems.

Cause this phenomenon is mainly related to the spark plug and joint structure of the high tension line, the high tension line not connected to the metal parts of the spark plug, with the distance of a few millimeters, due to the working voltage of the spark plug is tens of thousands of volts of high voltage, the impurities in the air can easily be under such high voltage ionization, and adhere to the high tension line between the metal cap and formed a layer of scale on the insulators.

This kind of phenomenon calls spark plug corona phenomenon, do not affect spark plug to work normally, more be quality problem.

The spark plug skirt is broken

This phenomenon is one of the most dangerous spark plug failure, light spark plug ignition failure, heavy broken ceramics caused engine cylinder, and the replacement of new products may not be able to completely solve the problem, it is likely that the car after a period of time after a similar failure.

The reason has nothing to do with the quality of the spark plug itself. The real culprit is the abnormal injection of the nozzle. When the nozzle works normally, the gasoline injected by the nozzle is in the atomized state. In this state, the gasoline cooled around the spark plug skirt body is uniform, and no internal stress is generated. But when the nozzle blockage due to various reasons, abnormal injection, spewing gas atomization effect is greatly reduced, if jams, spewing gas is liquid water, when the water column of gas injection on the high temperature of the spark plug, spark plug the skirt at different location of the ceramic body is cooling degree is different, so can produce internal stress due to temperature errand porcelain, accumulated for a long time will lead to skirt ceramic body fracture.

For example, in winter, when the glass is full of water, the glass will not crack, but only half a cup of water, because of the heat is not uniform, the glass thermal expansion and contraction of internal stress, so that its rupture.

Spark plug in the case of no problem in the selection, if the above phenomenon, be sure to clean the nozzle, so as to fundamentally solve the problem. At the same time, to remind the owner friends, according to the car maintenance manual, once every 20000 km should clean the nozzle, to avoid nozzle clogging, and also recommend, usually don't use fuel additives and oil pipeline cleaner products, such as inferior colloid content of these products is very high, is the culprit nozzle clogging, maintenance must use big brand products and to have an aptitude for repair professional repair shop.