Spark plugs are an integral part of the engine of any gasoline car. It is this part that provides the necessary spark, which then ignites the mixture of air and fuel in the combustion chamber. Like all other engine parts, they can fail, and if at least the slightest signs of malfunction of the spark plugs appear, they must be eliminated.
If the part fails, the load on the ignition coil also increases , which, as a result, can also break. The cost of a candle is not comparable with the price of a coil. If you continue to drive with faulty candles, the driver will observe unstable operation of the power unit at idle. Often, when everything is in good condition, the engine runs at 1000 rpm. smooth and soft. In the event of a candle malfunction, the tachometer needle will skip, and the motor will vibrate and emit unpleasant hard sounds.
Today, the ECU will help to detect signs of malfunction of the spark plugs. Several decades ago, this has not happened, and those who independently serviced their cars had to diagnose these elements. In order to make a correct diagnosis, you need to know the typical problems with candles and be able to identify them visually.
What are the signs of malfunctioning spark plugs?
So, when the candles fail, the motor is broken. The engine refuses to fulfill the functions assigned to it. Here is a list of signs in which urgent intervention by a specialist is necessary.
If the engine starts with serious and visible difficulties, this is a signal to the owner about the need to diagnose and replace the spark plug. Also, the nature of the engine will tell about the failed candles: if the unit troits, twitches, but there is no traction and power, then this is another sign. At the same time, often with malfunctioning spark plugs
, fuel consumption increases several times
, and CO prevails in the exhaust gas composition. If there is low power or the motor does not want to gain speed when you press the accelerator pedal, then this also indicates the need for diagnosis.
If you pay attention to these basic signs of malfunction of the spark plugs in time, then the situation can be resolved. If you do not pay attention to these signals, the result will be disastrous.
The consequences of faulty candles
Detonation occurs in the cylinders, the result of which will be a powerful shock wave. It can provoke a detonation of the charge that still remains in the cylinder. After that, the motor will completely lose its power. During this exposure, the crankshaft, pistons and connecting rods suffer from severe overheating. Small parts also burn out and the oil film on the cylinder collapses.
When to change candles
Each auto-driver recommends scheduled maintenance during maintenance. But experienced drivers do not agree with these claims. Most motorists replace candles by mileage - every 20-30 thousand km.
Candle manufacturers recommend changing classic candles to 15 thousand km. Parts made of platinum can be changed less frequently - their term reaches 100 thousand km. Do not wait until the first signs of malfunction of the spark plugs appear. If poor-quality fuel is regularly poured into the tank, then candles will begin to accumulate soot, and failure will be earlier than the deadlines set by the manufacturers.
Diagnostics: looking for a candle with a defect
Problems can be identified visually even with the naked eye. However, the breakdown is obvious when the car is running unevenly and stalls. It is worth remembering that malfunctions of this kind make it impossible to ignite a fuel-air candle in a cylinder.
As a result of the fact that the fuel does not burn, it can get into the catalyst. In this case, a strong smell of gasoline will be felt. Another clear sign of a candle malfunction is a significant increase in fuel consumption. This happens because the mixture does not burn out completely due to misfire.
For efficient combustion in gasoline engines, it is necessary that the temperature in the cylinders reaches 400-500 degrees or more. This is possible by compressing the fuel mixture, which further increases the temperature. Only in this way is the mixture easy, and most importantly, completely, ignited and burned.
However, high temperatures do not have the best effect on the life of candles. Most often, layering is found on old parts. Also on the electrodes can be seen deposits that affect the quality of the spark. It should be remembered that on a working candle the electrode has a uniform color and a uniform shape, and any deposits are absent.
Spark plug testing
A normal part has virtually no burnout on the electrode. With such a candle, the motor will work like a clock.
It is important to know what kind of malfunctions spark plugs may be. This will help novice motorists.
Carbon black plaque
If plaque is visible on the grounding element, as well as on the electrode and the body of the candle, such a candle does not work properly. The reason for this is the improper preparation of the mixture. For example, the composition may be too much air or, conversely, not enough. Also, these deposits can appear as a result of contaminated air filters, malfunctions in the injection system, failure of temperature sensors or a lambda probe.
Candle oil
In this case, the grounding element, the housing and the electrode are coated with a uniform oil coating. These signs of spark plug malfunction occur due to excess oil in the engine cylinders. This phenomenon occurs due to oil overflow into the motor. In addition, this feature may indicate worn piston rings, the pistons themselves or valve guides. On cars with a turbo-compressor, candles in oil can talk about problems in the operation of the compressor.
Varnish deposits
If there are deposits of brown-yellow or green tint on the candle, then the most popular reason is the presence of additives in gasoline or in oil. These are symptoms of engine running on too lean fuel mixture or on gas.
Slag deposits
They can be observed on the grounding element, as well as not the electrodes. These are large deposits of fuel and oil. The reason for this may be the presence of additives in the oil, which are becoming increasingly popular among manufacturers of lubricants. It can also be the cause of the malfunction of both the engine itself and the ignition system. Often you can observe such signs of malfunction of the VAZ-2110 spark plugs.
The central electrode is molten
You can see the molten central electrode and the molten edge on the grounding element.
The reason for this may be overheating of the spark plug as a result of incorrect operation of the ignition system. These are signs of a malfunction of the VAZ-2114 spark plugs. On such cars, you can often observe problems with the ignition module.
The electrode of a candle very quickly worn out
On the electrodes and grounding elements, increased wear can be observed, as a result of which the material of the critical elements of the candle is damaged. The reason for this is low-quality gasoline with a lot of additives. Oil with additives can also lead to this. Quick wear of the candle can be observed with detonation or overheating.
Candle melted
This is evidenced by strong deposits on the grounding element and on the electrode. This happens due to the presence in the chamber of the combustion products of various deposits, which can spontaneously ignite. It may also be a sign of valve malfunction. Well, the most popular reason is bad fuel.
Worn connector
Often, candle wear occurs at the place where the spark is created. However, damage can also be on the other hand - where the high-voltage wire is connected.
The cause of this malfunction is the old connector on the wire or overheating.
Spark plug test
In turn, the candles are unscrewed with a special key and listen to the motor. If the engine has not broken the rhythm and continues to work stably with a normal sound, then an inoperative candle is pulled out. You can also disconnect the wire from the spark plug and touch it to the cylinder block. If there is no spark, then the candle needs to be changed.
Faults can also be reported by the electronic control unit. Take, for example, the French car Peugeot Partner Tipi. Spark plugs, the symptoms of which can be recognized not only by visual inspection, the owner can check using the computer. As you can see, this is not so difficult. In fact, knowing this is very important. Defective candles - improper motor operation, damage to critical components and expensive motor repairs. And if you know how the spark plugs work, and their signs of malfunction, big problems with the motor can be avoided.