bad spark plug symptoms

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bad spark plug symptoms
bad spark plug symptoms

Keeping spark plugs intact, checking on them regularly, and replacing when necessary is an essential part of car maintenance. Spark plugs perform one of the most important functions igniting the air/ fuel mix with an electric spark. You just can’t overlook the significance of well-functioning spark plugs. However, many people can ignore failing spark plugs for ages driving the vehicle that clearly shows all the symptoms. Or are they not aware of the telltale signs of bad spark plugs?

In this article, we are going to go through the list of the most frequent symptoms.

Signs of bad spark plugs

Letting the issue of failing spark plugs go unaddressed can end up in costly damages. Many car owners blame the malfunctioning of the vehicle on something else especially if the issues start to come up alongside with the check engine light, the situation that requires a bit of deciphering. However, there are very clear signs, and this is how you go about it:

Pay attention to the sounds your car makes
When your vehicle is idle, the engine normally gives out about 1.000rpm which results in a smooth continuous sound. You should pay closer attention to the spark plugs, if the sound is rough and jumpy making the entire vehicle vibrate.

Notice the way the car starts
The first thing that comes to mind when a car refuses to start is that it’s out of fuel. The reason you might dismiss though is faulty spark plugs that fail to generate a spark and drive the pistons. Over time, bad spark plugs can also drain the battery, so it’s only smart if you check both the plugs and the battery and replace them if needed.

Take action if your car makes stops
Bad spark plugs prevent one or more cylinders from firing as intended. This is likely to be the reason if you notice that your vehicle doesn’t start smoothly anymore stopping for a second and then proceeding instead. Another reason is an excessive amount of air being sucked in during the combustion process which is also caused by spark plugs out of order. Uncontrollable halts and slowdowns can be dangerous, especially in traffic. That’s why you need to tackle this issue as soon as possible.

Keep track of fuel consumption
Bad plugs mean bad gas mileage. If you notice that you have to refuel more often than usual, you might want to check the spark plugs since once they are out of order, it leads to incomplete combustion and a significant decrease in fuel economy.

Do something if you have troubles accelerating
Another tell-tale sign that the car needs servicing is unresponsiveness. If it feels like nothing is happening when you put the gas pedal down, or the vehicle just won’t react the way it did before, bad spark plugs may be at fault.

How long do spark plugs last?
While performing their mission, spark plugs get exposed to heat, oil, and gasoline. Everytime a spark is induced, a small amount of metal is removed off its surface. Over time, it results in decreased effectiveness that manifests itself in the signs described above.

Manufacturers claim that the average life expectancy of a standard copper plug is from 10,000 to 20,000 miles. Iridium and platinum plugs, however, only start to wear out after 60,000 miles. High performance spark plugs need to be replaced more often than regular ones.

Spark plugs need to be regularly checked. Even if the ones you use are extended-life, you still have to make sure that everything is alright every 30,000 miles.

How to check spark plugs
Checking spark plugs can be broken down into two steps:

Locating the spark plugs
Normally spark plugs are easily accessible from under the hood or bonnet of your car. To further locate them, you might need to look through the owner’s manual you received after buying the car.

Usually, when you look under the hood, you see from four to eight wires with spark plugs located at their ends. Depending on the type of the engine, spark plugs might be placed at the top or on the sides of the engine.

Before doing anything, you need to take precautions, read the owner’s manual, read a couple of articles on how to tell that a spark plug is bad, and make sure the engine is cooled down. The rule of the thumb is to check each and every plug for 

possible damage. One overlooked plug may result in costly damages in perspective.

Assessing the state
The difficulty is that it’s not like a spark plug can be either good or bad. There are different problems that might affect the spark plugs of your vehicle. Assessing the state of the plugs will help you figure out what to do next.

  • Normal. Well-functioning spark plugs are most likely going to look the way they did when they first were screwed in.
  • Red coating is usually a normal phenomenon caused by the use of lower-quality unleaded fuel.
  • Fouled plugs. A frequent condition that is to be addressed depending on the type of contamination. If the plugs are fouled with fuel, which you can figure out by a shiny coating on the tip, you might want to adjust your heat range as recommended by the car manufacturer. In case the tip and the side electrode are blackened, the plug is carbon-fouled which is usually caused by an excessive amount of fuel, leakage in the injectors, or malfunctioning wiring. Oil ash fouled plugs usually guarantee a visit to a car service. They are the result of worn piston rings or valve guides/seals.
  • Mechanical damage is easily noticeable as the plug looks beaten down lower than its natural position.


How to test a spark plug

There are several ways to find out if the spark plugs of your car function well.

  • If the performance of your car doesn’t change after disconnecting a spark plug, it means it doesn’t contribute and needs to be replaced;
  • To test if the voltage is transferred properly from the wire to the spark plug, disconnect the wire and press its end against a metal surface. You want to hear the crackling to make sure that the spark plug is alright;
  • Contaminated plugs and wires can distort the results of the tests. However, if nothing changes for the better after you cleaned the spark plugs, consider replacement.