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#articles@alians_auto ABOUT SPARK PLUGS.
Despite the simplicity of the structure of spark plugs, they need to be worked and handled correctly. They need to be cleaned correctly, selected and replaced correctly. However, even new options can sometimes cause problems - the car may run unevenly, sometimes there are jerks (shocks) when accelerating, as well as slight detonation. Many people immediately begin to look for the cause in the ignition system - of course, the spark plugs are new! However, the culprit may be a gap between the electrodes; just correct it and the engine will simply “sing”...
• Gap on spark plugs • How ignition works in a cylinder • The influence of the correct gap on the operation of the engine • Normal gap, what you need to focus on • How to check and how to set it • Modern technologies • First, a little definition.
The spark plug gap is the distance between the upper and lower electrodes, necessary for optimal operation and ignition of the fuel mixture. If this distance differs from the recommended standards, the engine will not run smoothly, and either twitching or detonation similar to “triple” of your unit is possible. In simple words, if the gap is different from the norm, set this way from the factory or by the seller, then you can shovel at least half of the motor, but you won’t find the reason. This is especially noticeable on carburetor systems. But first, I suggest starting with the device and operating principle.
If we talk about spark plugs, then this is like the last link in the ignition system, which is in direct contact with the air-fuel mixture. It is this element that sets it on fire, and does it either effectively and as laid down in the technical regulations, or ineffectively for a number of reasons (by the way, wear is often to blame).
After the fuel mixture (gasoline and air) has been supplied to the cylinders, the piston begins to go up and compress it, thereby increasing pressure. At the peak or, as is commonly called, the “top point,” the ECU gives an order and this composition ignites. Moreover, it is ignited by the spark plug - a spark runs between the electrodes, which is the catalyst. However, ignition may not occur, I am not currently considering options with a malfunction of the ignition system, the gap is simply set - the wrong one. Thus, “missing” may occur (that is, the fuel mixture does not ignite), which will cause your engine to operate with low efficiency, and sometimes it will not start at all (for example, in the morning in winter). But why does this happen?
• The influence of the correct clearance on the operation of the motor:
The gap is a really important parameter. It can either be big or too small.
If small values are set between the electrodes, then misfires will occur in the ignition system. The thing is that the spark that forms between the electrodes, which are as close to each other as possible, is not enough to ignite the fuel mixture. The spark, although strong, is not sufficient. This is why many cars will really jerk when driving and not develop enough speed. The carburetors may have flooded spark plugs, which will only cause problems – it will generally cause problems. The gap needs to be increased!
How much is a small gap? If we talk about size, it is approximately from 0.1 to 0.4 mm. We definitely check the candles after purchase, I’ll give practical recommendations below, but for now let’s talk about long distances.
You know, many manufacturers set the normal distance between the electrodes in advance. But over time, it can increase on its own. It's all about spark plug wear, which manifests itself with high mileage - this is natural. After all, the electrodes are made of metal, which, under the influence of temperature and constant electrical discharges, begins to slowly burn out. Both the upper one, which resembles the letter “G”, and the lower one suffer. The top one becomes thin, instead of a rectangular shape, it begins to be rounded, because the sides burn out.
The bottom one just sags down. Due to this distance, the spark that passes between the contacts weakens. And significantly! It may also not be enough to ignite the fuel. Often, because of this, the insulator of the lower contact is pierced; the whole point is that the spark tries to find the shortest path between the electrodes.
In winter, there is a high probability that the car simply will not start.
Another important aspect is that deposits in the form of soot may more often appear on distant electrodes; the spark “suffers” from the long distance, and so does deposits! It may not pass at all. Therefore, it is important after a certain mileage, with our fuel it can be already 15,000 km, to unscrew the spark plugs if necessary, change them, or clean them.
Large distance - from 1.3 mm and above. Normal gap, what you need to focus on.
We have very specific limits. Bottom from 0.4 mm (and everything below), top from 1.3 mm (and everything above). So what is considered the normal size for your car? You know, there are differences here too, they are connected primarily with the car’s ignition system, which can be roughly divided into three types:
1) For carburetor type, with distributor - normal clearance is from 0.5 to 0.6 mm
2) For carburetor type, with electronic ignition – 0.7 – 0.8 mm
3) Injector – 1 – 1.3 mm
Why such difference? The answer is simple - it's a matter of the ignition system and electrical circuit. The carburetor has the lowest voltage, so the spark will be weaker, and therefore the gap should be smaller. But the injector has the strongest energy system, so here the gap is increased, normal is considered to be 1 mm, and on many foreign cars it is 1.1 mm.
- How to check and how to set it.
The process is not as complicated as it seems at first glance. To begin with, we simply unscrew the spark plugs, then look for damage; if there is none, then you can first clean it, then check the gap. Of course, the gap can be measured with conventional measuring instruments, just a ruler. However, it is very difficult to determine 0.5 or 0.7 mm by sight! Therefore, now in stores you can buy so-called sets of “feelers” or special keys for checking the gap.
The probes look like metal curved letters “G”, with different sizes; we simply place them between the electrodes and determine the gap with an accuracy of 97%. If it is larger, for example on an injector than 1.1 mm, then the contacts are brought closer to each other, you can simply tap with the handle of a screwdriver. Published in contact /alians_auto. If it’s too close, then we move them apart from each other, again checking with a probe.
What I want to say in conclusion, many will think “come on,” why should I bother with some distance between the electrodes! Guys, very wrong thoughts.
Firstly, you can save on fuel, studies show up to 5 – 7%
Secondly, smooth engine operation is the key to driving safety.
Third, the correct gap between the spark plugs increases their service life; there is no chance that the insulator will break through (with an increased distance).
I would like to note that some companies, on the contrary, increase the number of contacts (electrodes), strengthen the coils and the ignition system, all so that the mixture is ignited better.
There are also more modern technologies now, which I think will soon replace them - such as plasma candles.
They have no electrodes at all, and the fuel is ignited by a beam of plasma that is generated by electricity. As they write, the production is now undergoing tests and they say that the combustion efficiency of the fuel mixture is increasing, and this means a little more power, a little more economy and environmental friendliness of the engine.
Notes and additions
— For spark plugs for carburetor engines with a contact ignition system for VAZ 2101, 2102, 2103, 2104, 2105, 2106, 2107 cars, the recommended gap between the electrodes of the spark plugs is 0.5-0.7 mm, for VAZ 2108, 2109, 21099, 2105, 2107 with a contactless ignition system 0.7-0.9 mm.
For injection engines of VAZ 2107, 2108, 2109, 21099 cars 1.0-1.1 mm.
An incorrectly set gap between the electrodes of the spark plugs leads to problems with starting the engine, unstable engine idle speed, jerking when starting and driving, “dips,” loss of power and throttle response, and an increase in the engine’s fuel appetite. Normal engine operation can only be ensured by a spark plug with a gap specific for a given engine type.
Regularly check the reliability of the connections of the high-voltage wires with the spark plugs, coil and ignition distributor.
With a smaller gap, the spark will be short and weak, combustion of the fuel mixture worsens, with a large gap, the voltage required to break through the air gap between the electrodes of the spark plug increases. In this case, there may be no spark at all.
There is no need to set the gap on multi-electrode spark plugs.
What are the differences between spark plugs?
Spark plugs provide the current discharge necessary to ignite the fuel-air mixture in the combustion chamber of the cylinders. The better the quality of the spark coming from them, the more powerful the operation of the “engine” and the lower the risk of incomplete combustion of the mixture, and therefore engine wear. The types of spark plugs depend on the design features of the engine: requirements for thermal data, the pitch of the connecting thread, and the number of electrodes. When choosing this part, you need to be aware of what spark plugs are available in order to choose the best option for your car.
How does clearance affect engine performance?
It is clear that the complete absence of a spark means problems with the starting coil, then the gap has nothing to do with it. In fact, the size of the gap has a direct impact on the full operation of the motor. To understand this, we need to consider the processes that occur in the combustion chamber of the engine at the moment when the air-fuel mixture is ignited by a spark:
- It compresses the mixture in the cylinder under the influence of the piston
- The fuel-air mixture is compacted to the limit
- For a spark to be successful, a good potential difference is needed, because the mixture becomes very dense when compressed
- Modern gasoline engines are equipped with an ignition system that functions properly only if all its elements and mechanisms are in full working order.
- Since the slightest disturbance in this well-functioning system, such as carbon deposits on the spark plugs, prevents the engine from operating at full power
- If the gap between the spark plug electrodes increases due to natural reasons, then there may not be enough electrical power to break through the dense mixture of fuel and air with a spark
- Naturally, the increased energy consumption to break through the mixture reduces the spark fuse. Accordingly, it may not be enough to ignite the working mixture in a timely manner
- In the vast majority of cases, there is a loss of engine power
- Having studied the process of car spark plugs, you may encounter a number of unknown factors.
- This is why the question “what kind of spark plugs should be used on a car?” there is a clear answer - original, prescribed by the manufacturer
- In addition, periodic checking is very important; during this check, the gap in the spark plugs is measured on a VAZ 21093 and the required value is set
- Each motor manufacturer, as a rule, indicates the required clearance that must be adhered to
Spark plug characteristics
Any variety of spark plugs has a number of general introductory information that must be taken into account when choosing a part. Here are the characteristics you should pay special attention to:
- Heat number is a designation that indicates at what pressure the gases will begin to ignite from contact with the hot area of the candle, and not from the discharge. If this indicator is lower than recommended for a particular engine, the part cannot be installed.
- Insulation data - the temperature of the insulator is determined by the operation of the “engine”. If the insulator cone heats up to 10,000 C, glow ignition usually occurs, which should not be allowed.
- Operating temperature (optimal parameter – 500-9000 C).
- Self-cleaning from burning resulting from burning of the mixture.
- The width of the gap between the central electrode and the side electrode (you can adjust it yourself).
- The location of the side electrodes, as well as their number (it is possible to have from one to four electrodes, with an increase in the number of which sparking is more stable).
Specific parameters are determined by the design features of the engine: carburetor or injector, power, thread length and diameter.
Checking the gap between the spark plug electrodes
When installing new spark plugs on an engine or checking old ones, it is necessary to measure the gap between their electrodes. Old spark plugs should be cleaned of carbon deposits. The check is carried out with a round probe of the required diameter.
When checking and replacing spark plugs, be careful - if the engine is hot, you can get burned.
Measuring with a flat probe will be inaccurate, since there is almost always a small indentation on the side electrode of the spark plug due to metal transfer to the central electrode. This is especially true for candles that have already worked for some time.
How they work
The general structure and operating principle are the same:
- In the upper (under the hood) part there is a contact terminal to which the ignition wiring is connected.
- The wiring carries a voltage of 20-35 thousand volts and is supplied to the central electrode, which is the cathode.
- The housing (made of metal) is screwed into a thread located on the cylinder head. It performs a conductor function from the “ground” of the car to the side electrode.
- Voltage leakage is prevented by a ceramic insulator that can withstand up to 10,000 C. Also, “protection” is provided by seals that prevent gases from escaping from the combustion chamber.
- There is a gap between the central and side electrodes, the size of which determines the discharge power: the wider the gap, the higher the discharge, and accordingly, the higher the probability of ignition.
Depending on the material of the electrodes. Since high electrical conductivity must be present, the following metals are used:
- the most common alloys are nickel and chromium (alloy with iron is possible) or chromium, titanium and iron;
- Nickel plated copper;
- platinum alloy (makes the spark plugs wear-resistant, so the electrode diameter is reduced to 1.1 mm);
- iridium spark plugs (the difference from conventional ones is that they provide enormous wear resistance, allowing the cathode diameter to be reduced to 0.7 or even 0.4 mm);
- an alloy of palladium and gold (installed on fireballs).
Silver, gold, and platinum coatings that enhance electrical conductivity are allowed, but these materials are used less frequently due to their high cost.
Depending on the heat number. Taking into account thermal parameters, there are “hot” and “cold” spark plugs:
- “Hot” can be set if the temperature in the combustion chamber is low due to the low compression ratio. Heat pure – 11-14. A good option for owners of carburetor cars driving low-octane fuel.
- “Cold” ones have an increased degree of heat transfer from the cathode and insulator: they are recommended for engines with a high compression threshold when driving on high-octane fuel. Heating number – from 20.
In both cases, spark plugs are used, but in the case of an injector, variations are possible. One of the important parameters for classification is the number of valves in the power unit. What is the difference between 8-cl and 16-cl spark plugs? First of all, the electrode material: for 16-cell, platinum or iridium is used. 8-cl. has a larger thread diameter. There is also a difference in the heat rating: for 16-cl it is higher, so they are more suitable for an injector.
How to choose candles
When determining the required types, you should be guided by the following characteristics, which depend on the characteristics of the motor:
- ignition features (electronic, contact, contactless, battery);
- features of the power system (injector or carburetor);
- amount of compression and compression.
It is important to pay attention to the quality of the fuel used. Is it worth taking iridium spark plugs, which supposedly can withstand a mileage of 60 thousand km? There is no definite answer, because it is unknown how they will behave in a particular motor. Therefore, in the absence of proper experience, it is better to carry out diagnostics from specialists.
The differences in spark plugs are associated with the rapid evolution of the automotive industry: new, more powerful models are created with new requirements for parts.
The car market is filled with a lot of manufacturer brands. The biggest difficulty is not only to choose the right ones according to the characteristics, but also to choose a manufacturer of high-quality spark plugs.
Candles
There is also some difference between the spark plugs of a carburetor and injection engine. Candles differ in gap and heat rating. For engines with a carburetor system, the gap should be smaller, for injection power units, correspondingly, larger. Heat number is a value characterizing the uncontrolled process of ignition of the emulsion from the hot parts of the candle. According to their thermal characteristics, candles are divided into:
- for cold ones (number 20 or more), intended for highly accelerated units;
- to medium (17-19);
- for hot ones (11-14), used for low-power internal combustion engines;
- to unified (11-20).
The heat rating increases with increasing power and volume of the power plant. Depends on the compression ratio: the higher it is, the higher the heat rating should be. It is necessary to select spark plugs based on the requirements of the manufacturer of a particular engine.
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What is the difference between injector spark plugs and carburetor spark plugs?
Post by Palmman » Jan 30, 2006 2:44 pm
It was necessary to buy candles (injector) for Matiz in the store. I was told it was out of stock. - Are there any shackles? - So they are the same ones that fit. — So the Matiz has an injector.
The question is what is the difference, if any. Yes, and which ones can be placed where. Those. Is it possible to install injection ones in the carb and vice versa?
Post by escapeman » Jan 30, 2006 2:47 pm
Post by Crocodile Mask » 30 Jan 2006 14:48
Post by Mr. PZ » 30 Jan 2006 14:50
Post by Palmman » Jan 30, 2006 2:51 pm
Post by Mr. PZ » 30 Jan 2006 14:52
Post by escapeman » Jan 30, 2006 2:54 pm
Post by Crocodile Mask » 30 Jan 2006 14:57
Post by Mr. PZ » 30 Jan 2006 16:15
Post by Crash » Jan 30, 2006 4:29 pm
differ in the gap on most cars, on the engineer the gap is larger
“winter” candles have a lower heat rating
Post by Crocodile Mask » 30 Jan 2006 16:56
Post by dasvidos
