The controversy surrounding spark plugs has noticeably subsided today. It seems to us that there are several reasons: the assortment of candles in stores is wider than ever, the quality of fuel in the country has improved somewhat, and the fleet has become younger and more "foreign". Nevertheless, questions continue to come to the editorial office. Some are interested in general information - why, for example, do you still need multi-electrode candles? Others are concerned about purely personal problems: look at the photo of the candle and diagnose the motor ... Answers to a dozen such questions are given below.
What are the advantages of multi-electrode candles? Is it true that there are more sparks on them than on “ordinary” ones?
Let's immediately dispel the tenacious myth about "multi-spark" candles: they do not exist in nature. There can be any number of side electrodes, but the spark discharge is always the same. Vendors often demonstrate the "multi-spark" mode on the stands, which gives the impression of a simultaneous discharge in the form of a glowing ring, but this is just an optical illusion, like in the movies.
As for the advantages of multi-electrode candles, they are. The first is the resource: due to the distribution of the load between the side electrodes, the rate of their erosion is reduced. By the way, that is why they are often installed in engines with difficult access to candles. The second is the presence of the so-called "open spark", in which the flame front does not get stuck in the interelectrode space, but goes into the combustion chamber. The combustion rate increases, which slightly increases the power of the motor and improves its efficiency. The third advantage is a relatively small number of fakes of such candles.
Flaws? Relatively high price plus the inability to set the desired interelectrode gap ...
Why do we need all sorts of "jewels" such as iridium electrodes?
A resource of 90–100 thousand km for such candles is a common thing.
Then, the service life of iridium, platinum and other “thoroughbred” candles is several times higher than that of “mongrel” ones ... At the same time, refractory electrode materials make it possible to increase the field strength in the interelectrode space, while at the same time clearing the way for the flame front. And a more powerful spark discharge, among other things, contributes to a good self-cleaning of the candle.
Why do pre-chamber candles not take root?
That which has obvious advantages takes root. In particular, a kind of "microprechambers" - recesses in the electrodes of individual branded candles - contribute to the stabilization of the discharge at the edges of such recesses. Such recesses can be both on the side (Denso) and on the central (NGK) electrodes. At the same time, there is a certain technical effect.
As for the "full-fledged" prechamber candles, they are often used in the engines of Formula 1 sports cars. The fact is that such engines operate at high speeds, at which ventilation problems simply do not arise. But at minimum idle speed, and even at low loads, the mixture in the cylinders moves much less intensively, and therefore the inner chamber of the candle actually suffocates. This is exactly what is observed, as a rule, when trying to stupidly install something pseudo-sports on your engine.
What gap should the spark plugs be?
Complex issue. The number one authority in this matter is the manufacturer of the car, more precisely, the engine. True, today such recommendations are addressed only to servicemen: the consumer is blocked by all means from access to the engine compartment (and, in general, they do it right).
Another thing is funny: even the recommended gap cannot be the same for all types of candles. For example, for the same iridium, it can certainly be more than for the classic ones! But no one usually gives such recommendations. Therefore, its specific value is always individual for the candle-motor tandem. In the general case, the larger the gap, the stronger the spark and ignition source. We also add that with an increase in the gap, the probability of shorting the electrodes by soot bridges decreases.
The danger of an excessive increase in the gap is obvious: the larger the gap, the greater the required breakdown voltage. And the discharge doesn’t care where to “shoot”: it can also pierce the coil if it decides that it’s easier for him ...
What are plasma candles?
We don't know... The question rests solely on terminology, because any spark discharge can be called cold plasma. Therefore, the attempts of individual manufacturers to call their candles plasma is a consequence of illiteracy, as well as the desire to play on the inexperience of consumers. All candles are either plasma or not: the appropriate terminology simply does not exist. But to call only candles of our own production as plasma, without honoring our colleagues in the shop with the same, is simply incorrect.
Why are candles getting thinner and thinner? Even the turnkey size used to be 21 mm, and now it is 14.
Candles with M14x1.25 threads and a large hexagon were used on engines with two valves per cylinder. At the same time, the candle most often approached the combustion chamber from the side and there was plenty of space to place it. On modern engines with four or even five valves, the only place to place a spark plug is in the center of the combustion chamber. The candle is screwed into the cylinder head through the candle well, which "steals" the space from the valves and the jacket of the cooling system. That is why it is necessary to make more and more thin candles and small diameter wells.
The spark plug pulled out of the engine is covered with a layer of oil. What is the reason?
Oily spark plugs can be a sign of relatively easy to fix problems, such as too high engine oil or clogged crankcase breathers. But it could be caused by much more formidable problems, such as worn piston rings, broken valve guides, and faulty valve seals.
It was possible to turn out the candle with great difficulty, and the new candle does not screw in completely. What to do?
It is obvious that the previous candle was not wrapped in the cylinder head. Therefore, part of the thread in the head is covered with soot and does not allow a new candle to be screwed in. In such a situation, it is best to make grooves along the threaded part of the old candle with a needle file. This will turn the candle into a kind of tap. Further, having applied a thin layer of grease to the thread of the candle, we screw it into the hole, periodically “handing it back” until we go through the entire thread. We wipe the candle hole with a swab of lint-free rags and screw in a new candle. It is advisable to use a special high-temperature lubricant or simply rub the threads with graphite.
The insulator of the candle has acquired an incomprehensible reddish color, although there is practically no soot. What is this?
Red soot on a candle is formed during the combustion of gasoline with a high content of iron-containing additives based on ferrocene. Unscrupulous manufacturers use these additives to increase the octane number of gasoline. The additive is not useful for both candles and the engine. Seeing this color of a candle, think about changing the gas station.
Should I clean the spark plugs between changes?
With a working engine, there is little carbon deposits and cleaning of the candles is not required. If the candles are covered with abundant soot during short runs, then this is an occasion to repair the engine, and not to clean the candles. In addition, the threaded holes for the candles are made of aluminum, and countless twisting and screwing can lead to thread stripping.
Fellow car enthusiasts, tell us, have you met with any unusual defects in candles?
Detailed tips for checking the ignition system.
Try not to crank the engine with the ignition on and at least one high-voltage wire removed!
The fact is that the ignition coil, when the current in its primary circuit is interrupted, creates a voltage in the secondary circuit. It is limited by the breakdown voltage in the candle, i.e. voltage at which a spark occurs.
If you remove the high-voltage wire, then the high voltage is not limited, and there is a very high probability of electrical breakdown in another place, for example, the cover of the distributor. Therefore, it is necessary to check the spark on the candles of Japanese cars with their delicate electronics as follows. Unscrew all the candles and tie them with bare wire, for example, aluminum, in a row. Fasten the free end of the wire to the "mass", i.e. screw it to any unpainted part on the engine, and put all the tips of high-voltage wires on the candles.
Now, scrolling the engine with a starter, you can observe a spark on all the candles. If the spark is very thin (filamentous), it can be argued that the switch has failed. If the candles are dirty and wet, they must be cleaned, but it is better to replace them with new ones. Set the same gaps on the candles. The larger the gap in the candles, the better the combustible mixture in the cylinders will be ignited, but the higher the probability of failure (electrical breakdown) of any elements of the ignition system. Turn the starter 10-20 revolutions.
The spark should jump only between the central and side electrodes (in the same place), be thick, click loudly and be purple. If each electric discharge will at least by some sign differ from the previous discharge and from the discharges on neighboring candles, then it is necessary to look for the cause, because. this indicates a malfunction (in this case, the engine may start, but it will work unevenly).
Now set a gap of 2-4 mm on one candle and again turn the engine with a starter. If there is no spark on a candle with a large gap, or it changes in power with each click, then the ignition coil is most likely faulty. Another reason may be that there are leaks in the high-voltage part of the system (cracks, breakdowns, etc.).
Measure the electrical resistance of the wires. It should be about 5 kΩ and not differ by more than 1 kΩ from the resistance of other wires. Although many engines work quite tolerably even with a resistance of high-voltage wires of about 15 kOhm. Very often, the reason for the lack of spark is the failure of the switch.
Spark plugs are the most important part that is necessary for work. The main task is the formation of a spark in the combustion chamber, due to which it is possible to realize the ignition of the fuel-air mixture in the cylinder.
Note that any violations in the process of sparking lead to the fact that the engine begins to lose power, increased fuel consumption is noted, reactions to pressing the gas pedal slow down, the power unit starts to work unstably, troit, has toxic exhaust, etc.
At the same time, for experienced motorists and professional auto mechanics, diagnostics by the color of spark plugs is a reliable way to determine the condition of the entire engine, identify possible problems and failures. The fact is that these elements are in the combustion chamber and are a kind of status indicator.
Such knowledge can be useful both in the case of checking the candles themselves or in the process of searching for various engine malfunctions, and when buying a used car with an unknown history. Next, we will consider what the correct color of spark plugs should be, as well as what color of spark plugs, which means and what engine failures indicate in one case or another.
Read in this article
Different color spark plugs: what does it indicate
As already mentioned, the appearance of the candle allows you to evaluate the quality of work and the general condition of the entire engine, as well as its individual components and mechanisms. We note right away that it is necessary to start inspecting the candles only after the engine has warmed up well and reached operating temperatures, and also worked in a loaded mode before inspection.
In other words, the car should drive at least 20-30 km. At the same time, the best approach can be considered candle diagnostics after a long drive along the highway, when the car has traveled at least a couple of hundred kilometers.
- So, let's look at the meaning of the colors of the spark plugs, which can be seen after they are unscrewed on various internal combustion engines. To begin with, the normal color of a spark plug is when the skirt of the center electrode is light brown, there is practically no carbon deposits and various deposits. There should also be no smearing visible. This color of working candles indicates the efficiency of the engine, the completeness of combustion of the mixture in the cylinders, the absence of oil consumption due to wear or.
- If, after unscrewing, it is clear that black fluffy soot has accumulated on the central electrode, then this indicates problems with or air supply to. As a result, the engine runs on an enriched mixture and overuses fuel. The reason may be the need for additional, malfunctions, pollution.
- In the case when the spark plug electrode is covered with a grayish light soot or white coating, then this color indicates that the engine is running on a too lean mixture of fuel and air.
In such a situation, it is necessary to diagnose the internal combustion engine in depth, since a lean mixture in loaded modes leads to severe overheating of the spark plug and the entire combustion chamber. As a result, these overheatings can cause. If the spark plugs are white, the reasons may be in disturbed carburetion processes, excess air may be sucked in, sensors may malfunction, etc.
In no way should one forget that a low glow number of candles or poor fuel quality, as well as early ignition, can lead to the fact that the central electrode and the area near it will be covered with a white coating. In parallel, it should be borne in mind that ICE malfunctions and engine operation at critical temperatures can also be the cause of the formation of such a white coating.
- The color of soot on spark plugs, which is more like a brick color (has a shade close to brick red), indicates that the power unit is running on fuel with an excessive amount of metal-containing additives in its composition. At the same time, it is important to know that red spark plugs will not be able to work properly in the engine over time, since the deposition of heavy metals (for example, lead) on the spark plug insulator begins to conduct current. As a result, the spark does not pass between the electrodes, and the element itself loses its performance.
- It is also possible to make a diagnosis of the unit and determine its condition by the color of soot if, after turning out the candles, traces of engine oil are visible in the thread area. As a rule, in this case, the engine starts with great difficulty, troit on a cold one, although after warming up the internal combustion engine with oily candles, it starts to work more or less stably. After turning out, the lubricant gets on top of the thread of the candle, but this does not mean that it is initially oiled in the lower part.
In any case, the presence of fresh oil on the spark plug and in the combustion chamber may indicate problems with (oil seals) and indicate other malfunctions. Such a motor without repair will start poorly, “eat” oil and. Note that sometimes they lead to the fact that oil accumulates outside, that is, in candle wells.
In such a situation, it is necessary to additionally check the candle wells for filling with lubricant, which will help to avoid inaccurate and hasty conclusions in the future.
- If it is noticeable that the central electrode of the candle and the skirt are covered with engine oil, and unburned fuel is found on the candle, then the cylinder from which the candle was unscrewed does not work, but. As a rule, in this case, the engine noticeably troit, loses power, consumes fuel. There can be many reasons for this, ranging from a malfunctioning spark plug or ignition system to serious engine breakdowns (low compression, valve burnout, destruction, etc.). The most alarming sign can be considered the presence of small metal particles that stick to oily soot. This indicates the destruction or significant wear of any part or element, after which the metal fractions entered the combustion chamber. In such a situation, the engine must be disassembled, troubleshooted and then repaired.
- Obvious destruction of the central electrode and its ceramic skirt will indicate that the engine has been operating for a long time in conditions, early ignition is set, fuel with an unsuitable octane rating for a particular type of internal combustion engine is used, or the candle has poor workmanship, marriage or a manufacturing defect.
Naturally, in this case, the cylinder does not work, the motor troit, etc. The risk of spark plug failure is that broken parts can get stuck under the exhaust valve and cause other more serious damage. The result in this case will be the need for repair.
- Abundant accumulation of ash deposits on the candle, regardless of the overall color of the soot, indicates that the oil is consumed for waste in the combustion chamber. The most common reason is. In case of problems with the rings, an increased oil consumption is observed, in the gas recirculation mode, the exhaust acquires a bluish tint, the smoke becomes oily. It is enough to bring a sheet of clean white paper to the exhaust pipe and turn it off at idle, after which greasy oil stains remain on the sheet.
Having figured out what color the spark plugs should be in a particular case, you can diagnose the internal combustion engine. Separately, we add that it is very important to follow the rule when, before unscrewing the candles, the engine must warm up and work under load.
The fact is that if, immediately after a cold start, malfunctions or failures were noticed in the operation of the engine, and then the candles were unscrewed to check, then in many cases you can see gray-black soot. At the same time, such carbon deposits do not yet mean that the engine has a problem associated with the constant formation of just such deposits, malfunctions in mixture formation, etc. Simply put, at the time of a cold start, the mixture is enriched. It turns out that the malfunction, for example, lies in the ignition system, and black carbon deposits and flooded candles do not indicate problems with the power system (injector or carburetor).
As already mentioned, in order to obtain reliable data, before unscrewing the candles by car, you need to drive about 30, or even better, two or even three hundred kilometers, and along the highway. If the condition of the engine is of concern and you need to diagnose by candles and their color, then the following actions will be most correct:
- select new candles that correspond to the recommended physical dimensions and glow number for a particular internal combustion engine;
- refuel high-quality fuel at a proven gas station;
- after installing the candles, go on a trip along the highway, which will allow you to cover a distance of at least 30 to 300 km;
Only after these actions can the candles be unscrewed, after which one can judge the operation of the internal combustion engine by their color, soot and condition. It should also be taken into account that in the CIS the quality of fuel is significantly inferior to fuel in European countries. It turns out that the declared service life of any spark plugs, regardless of type, brand, design features (iridium, multi-electrode, platinum, etc.), as well as other differences, it is desirable to reduce by 20-30%.
It is important to understand that although many manufacturers guarantee the normal operation of candles for about 30 thousand km, taking into account the quality of domestic fuel, this figure in practice may not exceed 15-20 thousand km. For this reason, it is recommended to unscrew the candles in parallel with each scheduled maintenance (10 thousand km) to check them, as they may need to be cleaned of carbon deposits, adjust the gaps, or even replace them prematurely.
Finally, we add that the color of the spark on the spark plug can also partially indicate the presence of problems with the candle itself or the ignition system. Ideally, the discharge should be stable and also have a rich, bright blue color. It should be noted that the color of the spark on the spark plug can also change from reddish to white or yellow.
In this case, a more important indicator is not what color the spark should be on the candle, but the discharge power and the breakdown depth. In parallel, it is recommended in conditions of increased pressure in the combustion chamber. There are special stands for such a check, since there are quite common cases when there is a spark during a normal check, but after screwing it into the engine, certain failures occur.
Read also
What does the color of soot on the spark plug indicate, why soot of one color or another is formed. How to clean spark plugs from soot with your own hands, tips.
