The role of spark plugs
Spark plugs are an essential part of a gasoline engine, but many people may have heard of the name, but may not be familiar with it.
So, let's talk about spark plugs first.
What is a spark plug?
A spark plug is a component that generates a spark from the tip by passing high voltage through its body.
In automobiles, the ignition system includes spark plugs that generate sparks, ignition coils that generate high voltage, and plug cords.
role
Even if you send gasoline to the engine, the engine will not move by itself.
So, the spark plug ignites the gasoline and causes it to explode, powering the engine and allowing the car to run freely.
How do you light a plug?
A spark plug is a device that ignites the air-fuel mixture with the power of electric discharge.
Using static electricity to apply a large voltage to the center electrode of the spark plug body, electricity that has no place to go jumps out to the electrode attached to the outside of the spark plug.
The spark plug body can be said to be a part that is very prone to failure because it causes an explosion in the engine.
flying spark
When the high voltage generated by the ignition device is applied between the center electrode of the spark plug and the installation electrode, the insulation between the electrodes is broken and a discharge phenomenon occurs in which current flows.
This spark energy causes an ignition explosion in the compression mixer.
A strong spark can be generated between the electrodes accurately and reliably at the specified time to trigger the combustion of the air-fuel mixture.
ignition
Ignition by an electric spark produces a chemical reaction in which fuel particles between electrodes are activated by a spark discharge.
Since reaction heat is generated and a flame kernel is formed, this heat activates the surrounding air-fuel mixture and eventually spreads the combustion to the surroundings by itself.
However, if the quenching action of the electrode is greater than the heat generation of the flame kernel, the remote will be extinguished.
If the plug cap is wide, the flame kernel will be large, and the quenching effect will be small, so you can expect reliable ignition.
Change in discharge voltage
The ignition device usually generates a secondary voltage of 10-30kV.
When the primary current is interrupted, the secondary voltage rises and reaches the discharge voltage of the spark plug, generating a spark.
Called capacitive voltage, the discharge is caused by the electrical energy initially stored in the secondary circuit, the current is large but the duration is short.
Coil electromagnetic energy, called an induced spark, has a low current but a long duration.
Structure of the plug
The insulator insulates the terminal from the center electrode to the housing and prevents high voltage from escaping outside the electrode.Since the lower part of the insulator protrudes into the combustion chamber, high-purity alumina, which has excellent heat resistance, mechanical strength, dielectric strength at high temperatures, and thermal conductivity, is used.
Also, it is a terminal to connect a high tension cord that flows a high voltage current from the ignition device.
A terminal nut is installed to accommodate most plug cords in the world.
In addition, this part can be removed for models that do not require a terminal nut.
Spark plug operating environment
Inside the engine, a mixture of gasoline and air is compressed, and the compressed mixture is ignited by a spark plug to generate energy.
Generally, the temperature inside the engine reaches 2,000-3,000℃ and the pressure inside the engine reaches 3,000-5,000Kpa during the explosion.
The number of sparks that the spark plugs emit is 2,000 to 3,000 sparks per minute while driving on expressways.
Spark plugs must continue to produce sparks accurately in this harsh environment.
Spark plugs are required not only to produce sparks, but also to have ultra-high performance, such as durability that can withstand this environment.
What is an ignition coil?
An ignition coil is a transformer that generates the high voltage required for ignition.
Two coils with different numbers of turns are prepared, and high voltage is generated using self-induction and mutual induction.
Older cars used one ignition coil to power all spark plugs in the engine, but modern cars have one ignition coil for each spark plug.
This enables a stable power supply and detailed control by computer, and dramatically improves fuel efficiency and engine power.
Replacement Frequency of Plugs and Estimated Timing: Maintenance
how often do you replace it?
The recommended replacement period varies depending on the spark plug material.
For general spark plugs, the manufacturer recommends replacement at 20,000 km .
Platinum and iridium type spark plugs are recommended to be replaced every 100,000 km .
However, even for vehicles that use iridium plugs, there are cases where 20,000 km is recommended depending on the part where iridium is used, so be careful.
For details, it is better to check the manufacturer's HP or the plug manufacturer's HP.
WHY REPLACEMENT?
Spark plugs shoot sparks between separate electrodes.
And the sparks that fly nearly 3,000 times per minute have great power and cause electrode wear.
Electrode wear causes two things:
- Rounded electrode corners
- The gap between electrodes becomes wider
Rounded electrode corners
If the corners of the electrode are rounded, it will not produce a stable and strong spark .
Just as lightning strikes a sharp object, the spark of a spark plug also jumps to the sharp corners of the electrode.
A sharp corner means that spark plugs are more likely to spark.
However, with continued use of spark plugs, the corners of the electrodes wear out and become rounded.
Then, the electricity loses sight of where it is easy to fly, and it becomes impossible to generate a stable and strong spark.
The gap between electrodes becomes wider
The wider the gap between the electrodes, the less sparks will fly.
The gap between the spark plug electrodes is determined by a predetermined gap value, and if the gap is too wide or too small, it will not be possible to produce a stable and strong spark.
If the gap between the electrodes becomes too wide due to continued use and wear, it will not be possible to discharge, and in the worst case, sparks will not fly.
Advised to replace spark plugs
Many people may have been told that it is time to replace the spark plugs during an inspection at a dealer.
Unlike engine oil, spark plugs are not something that needs to be replaced frequently and are not cheap parts, so I think many people are hesitant.
However, spark plugs are considered consumables.
Automobile mechanics judge the need for replacement by comparing the wear and mileage of the spark plugs.
While listening to professional advice, it is better to make a decision to replace.
What will happen to your car if you don't change the spark plugs?
There are several malfunctions caused by spark plugs, and the typical ones are the following three.
- Poor engine start
- Unpleasant vibrations coming from the engine
- do not accelerate
The presence of spark plugs is essential for the engine to run.In
other words, the engine will not run properly if the spark plugs do not function.
The number of spark plugs is the same as the number of cylinders in the engine.
Usually 3 to 4 for mini vehicles and 4 to 8 for regular cars.
Some Mercedes-Benz cars are equipped with 24 in one car.
There is a low probability that all of the parts that exist in one unit will fail at the same time, and in many cases, part of them will fail.
Also, even if one spark plug fails, the engine will often start if the other spark plugs are functioning.
However, if a part is out of order, the engine will not start well, or the output will drop, resulting in poor acceleration or vibration.
It's old, but if the mileage is low, is it okay not to replace it?
As mentioned above, spark plugs are generally replaced based on the mileage.
However, I've also heard of people recommending replacement even though the mileage is low, and of failures caused by spark plugs.
In this way, even though the mileage is low, the usage of the car that is common to those who say is Choinori.
Choinori refers to how to ride in a short distance, such as shopping at a nearby supermarket or picking up and dropping off.
Choinori can actually do more damage to your car than overrunning, and it's no exaggeration to say that spark plugs are the most affected.
Also, be careful of vehicles that have a lot of idling while stopped.
plug cover
It is a plug cover that is often found in Choinori cars.
This means that the tip of the spark plug is wet with gasoline.
The reason why the plug gets wet due to Choinori is that there is an operating temperature in the engine, and it is designed to produce energy most efficiently between about 80°C and about 110°C.
However, since the engine stops before it reaches the operating temperature, the fuel does not burn properly, and the gasoline sticks to the spark plug and gets wet.
Then, the spark of the spark plug does not fly well, and carbon accumulates in the terminal of the spark plug.
And you can't ignite it properly, and you're going to invite a malfunction.
This condition is obvious if a professional mechanic sees it, so it is recommended to replace it regularly even if the mileage is low.
Spark plug replacement work
Most spark plugs are mounted directly above the engine.
As a result, many people do their own spark plug replacement.
Depending on the car, it may be necessary to remove the engine air duct or manifold, but if you buy the tools, relatively anyone can do the work.
A special tool called a plug wrench is required to replace the spark plugs.
The size of the plug wrench required varies depending on the car model, so purchase the plug wrench that fits your car.
However, extreme caution is required during installation.
If you break the screw hole of the spark plug, or if you overtighten the spark plug and damage it, you may not be able to fix it unless you replace the engine itself.
If you are doing this for the first time, it is a good idea to have an experienced spark plug changer or a professional mechanic help you out.
where you can change spark plugs
Spark plugs can be replaced at the following locations.
- - Dealer
- - Car parts point
- - Repair shop
- - Exchange by yourself
When you replace it at the dealer, you will use a genuine product, so the repair cost will be expensive.
You can get it replaced at a car supply store or repair shop, and the price is lower than the dealer.
Also, you can replace it yourself, but if you do it poorly, you may damage the screw hole where the plug is attached.
Breaking the screw holes will result in additional repair costs.
Therefore, if you cannot replace it yourself or are not confident in the replacement work, consult a professional.