The internal combustion engine is a complex mechanism where each element plays a critical role, but it is the ignition system that most often causes unstable operation of the engine. When the car begins to twitch during acceleration or increases fuel consumption, experienced drivers first look at the state of spark-forming elements. Ignition plugs They are an indicator of engine health, and their timely diagnosis avoids expensive repairs of the cylinder-piston group.
In this article, we will take a detailed look at all the existing methods of inspection, from visual inspection to the use of professional equipment. You will learn how to determine the color of the soda to determine the problems with mixture formation and why potassium You must strictly comply with the manufacturerβs recommendations.
Ignoring the first signs of malfunction can lead to a coil breaking or failure of the catalytic converter. Therefore, regular check of the status of contacts and the gap between the electrodes is a mandatory procedure for each owner of a gasoline engine.
There are several diagnostic methods that can be performed both in a garage and on a specialized stand. The choice of the particular method depends on the tools and symptoms your vehicle is displaying at the moment.
Visual examination and analysis of charcoal
The first and most affordable way of diagnosis is a careful study of the appearance of the twisted elements. The color and structure of the deposits on the insulator and electrodes can tell us more about the processes taking place inside the combustion chamber than just the fact that there is a spark. Normal is the condition when the insulator has a light brown or grayish hue, and the electrodes do not have severe damage.
If you find a black velvety plaque, this indicates the engine's operation on the enriched-mix. This often happens when nozzles malfunction, problems with the oxygen sensor or when installing candles with too high a potassium number for this operation mode. In this case, the fuel does not burn completely, clogging the pores of the insulator with a conductive layer.
β οΈ Warning: If oily deposits of black color are visible on the insulator, this is a direct sign of oil entering the combustion chamber through worn oil caps or piston rings.
A light or light gray coating with melted areas indicates overheating. This can be caused by early ignition, the use of low-octane fuels, or the installation of too-hot candles. Ignoring this feature leads to burnout of the valves and the destruction of the piston.
For an accurate interpretation of the condition, use the following table of matching the color of the coarse and possible malfunction:
| Color/Nagara type | Probable cause | Recommended action |
|---|---|---|
| Brick-red | Fuel additives (ferrocenes) | Replace gas stations, clean contacts |
| Black dry (soot) | Excess fuel, weak spark discharge | Check the nozzles, air filter. |
| Oily black | Oil hitting the cylinder | Defection of the engine, replacement of rings / caps |
| White with melting | Overheating, poor mix | Check the angle of advance, replace with "colder" |
Pay special attention to the gap between the side and central electrodes. Over time, the electrodes burn out and the gap increases, which requires a higher voltage to break down. Checking the gap is best done by probe, selecting a plate of the desired thickness, which should enter with light effort.
Check spark "by mass" and multimeter
The classic method of checking "for a spark" is known to every motorist, but it requires compliance with safety precautions. The essence of the method is to twist the candle, put on it a high-voltage wire (or coil) and apply the threaded part to the metal part of the engine ("mass"). When scrolling the starter should skip a powerful blue spark.
However, this method is not always correct for modern ignition systems with individual coils, since in the air a spark can slip even with a faulty element, but under pressure in the cylinder there will be no breakdown. There is also a risk of damage. switchboard Or the coil itself, leaving the chain open for a long time.
Why is there a spark in the air and the engine is not working?
The fact is that it is easier for an electric discharge to break through an air gap of 1-2 cm at atmospheric pressure than a mixture under a pressure of 10-15 atmospheres inside the cylinder. Therefore, the presence of a spark "on the table" does not guarantee 100% serviceability of the element in working conditions.
A more accurate tool of the home master is the multimeter. With it, you can check the resistance of the candle itself (for resistor models) and the integrity of high-voltage wires. The resistance must be within the limits specified by the manufacturer, usually between 2 and 8 kΞ©.
When checking the wires, pay attention to the absence of cracks and breaks. At night, you can see "spirit dances" - a spark jumping through the damaged insulation of the wire. This phenomenon not only disrupts the engine, but also creates interference for on-board electronics.
- π¦ To check wires in the dark, you can use a sprayer with water: sprinkle the wires when the engine is running - the breakdown places will immediately be illuminated by sparks.
- π Check the gap of the candle only with a round probe, since the flat one can give an error due to the wear of the electrodes.
- π When checking with a multimeter, always turn off the battery to avoid short circuit.
If the multimeter shows infinite resistance or, conversely, zero, the element definitely needs to be replaced. It is also important to check the reliability of the contact inside the high-voltage wire tip, since oxidation there is common.
Diagnostics without removal from the engine
There are situations when to twist all the candles at once there is no possibility or desire. In such cases, the method of sequential shutdown of the cylinders is used. When the engine is running at idle speeds, the connector from the ignition coil is alternately removed or the nozzle is disconnected.
If after disconnecting a particular cylinder, the engine operation changes (revs fall, tripping appears), then this cylinder worked. If the nature of the engine has not changed, then this cylinder has not functioned, and the problem lies either in the candleeither in the nozzle or in the compression.
This method allows you to quickly localize the problem cylinder without the use of complex diagnostics. However, it requires caution: on some modern cars, turning off the nozzles on the go can cause an error in the ECU or damage the catalytic converter due to the ingress of unburned fuel into the exhaust.
Another way of indirect verification is tactile. After a short engine operation (literally 1-2 minutes), gently touch (preferably with the back of the palm or through the glove) the exhaust manifold in the area of each cylinder. The pipe of the non-working cylinder will be colder, since it does not burn the mixture.
β οΈ Be very careful when touching engine parts. The exhaust manifold heats up to hundreds of degrees in minutes and can cause a burn.
Also about problems with candles can tell the behavior of the car. Ugs during unloading (when you remove your foot from the gas), dips when you sharply press the accelerator pedal and unstable idling are all signs that the ignition system is working incorrectly.
Checking on the spark discharger (stand)
The most professional and reliable way is to check on a special stand or using a portable spark discharger. This device allows you to create a pressure that simulates the conditions inside the cylinder, and test the ability of the candle to give a spark under load.
The device is a sealed flask with a pressure gauge and electrodes. The candle is screwed into the stand, compressed air is supplied, and a pressure of 10-15 atmospheres is created. If at such pressure the spark steadily skips between the electrodes, the candle is considered to be in good working order.
The advantage of this method is that it excludes false positive results. A weak coil or a candle that begins to βdieβ can give a spark in the air, but it will not be able to break through the spark gap in a compressed medium. This is critical for diagnosing turbocharged engines where cylinder pressure is significantly higher.
In addition to checking spark formation, the stand allows you to assess the tightness of the sealing ring and the absence of gas breakthroughs through the insulator. Cracks in the ceramics, invisible to the eye, under pressure can become a channel for leaking gases, which will lead to a missed ignition.
- βοΈ Stand check is mandatory when selecting candles for tuning engines.
- π The drop in the tension of the spark under pressure is the main sign of wear.
- π Visually, the color of the spark is clearly visible on the stand: blue means high energy, red or orange - weak.
At home, it is difficult to replace a full stand, but there are simplified testers that are screwed instead of a candle and have a transparent window. They allow you to assess the quality of the spark, without twisting the candle itself completely, although they do not create artificial pressure.
Typical errors in diagnosis
Often, car owners make mistakes that not only do not help to identify the problem, but also aggravate it. One of the most common is the installation of new candles without checking high-voltage wires or coils. If the cause of ignition misses lies in a broken wire, replacing candles will only give a temporary effect.
Another mistake is using candles with inappropriate potassium. Many people believe that the colder the candle, the better, and put sports models in the civilian engine. This leads to rapid overgrown with soda, as the self-cleaning temperature is not reached, and the engine begins to triple.
βοΈ Checking before buying new candles
An incorrect puff is also a frequent cause of problems. An unwounded candle can cause a kalyl ignition due to a violation of the heat sink, and a twisted one can lead to damage to the thread in the cylinder head or destruction of the insulator.
Ignoring the state of the throttle and air filter when replacing candles is another point. Dirty air and improper throttle operation can quickly spoil even new expensive ignition elements.
When installing new candles, always use a dynamometer key. The moment of puffing depends on the diameter of the thread and the material of the block head (aluminum or cast iron) and is usually 20-30 Nm.
Also, do not try to βrestoreβ old candles by calcining or cleaning with sandpaper. Modern candles with precious metals (iridium, platinum) have the finest electrodes, damage to which will make them completely useless.
Replacement and selection of materials
The service life of candles depends on the material of the electrodes. Ordinary nickel candles serve an average of 20-30 thousand kilometers. Platinum and iridium analogues are able to walk 60-100 thousand kilometers, maintaining a stable spark gap due to the high resistance of the metal to erosion.
However, the regulatory figures are relevant only when using high-quality fuel and a serviceable engine. The real resource may be much less. Therefore, it is recommended to check the condition every 15 thousand kilometers, especially before the winter season, when the requirements for starting the engine increase.
When choosing new elements, focus not only on the price, but also on the recommendations of the car manufacturer. The use of candles with an inappropriate carving size or insulator flight can lead to a collision of the piston with the electrode and overhaul of the engine.
Timely replacement of spark plugs is the cheapest way to prevent failure of the catalytic converter and ignition coils.
Modern engines with direct fuel injection have increased requirements for the ignition system. The pressure in the cylinder is higher, and the combustion conditions are tougher, so it is absolutely impossible to save on candles in such engines.
Summing up, we can say that regular diagnosis and proper selection of spark plugs is the key to the stable operation of your engine. Do not wait until the car stops starting, check the condition of the ignition system routinely, and it will respond to you with a confident start in any frost.
Can I check the candle with a lighter?
No, it's a myth. The lighter flame will not give any useful information about the condition of the insulator or the ability of the candle to work under pressure. Whatβs more, heating with an open fire can damage rubber seals or lead to cracking of ceramics due to uneven expansion.
Why do new candles turn black so quickly?
If new candles are quickly covered with black soda, the reason is not because of them. Most likely, the engine "eats" oil (wear CNG) or works on too rich mixture (problems with nozzles, DMRC, lambda probe). Replacing candles here won't solve the problem.
Does the octane number of gasoline affect the color of the candle?
Indirectly, yes. Using gasoline with an octane number below the recommended one causes detonation and overheating, which can lead to white plaque and melting of the electrodes. Also, some additives in low-quality fuel give a characteristic red coating.
Do I need to lubricate the candle carving before installation?
Most modern manufacturers cover the thread with a special anti-corrosion composition at the plant. Additional lubrication with graphite lubricant is permissible, but it is strictly forbidden to use copper lubricants or solidol, since they can change the moment of tightening and lead to boiling.