What Do Spark Plugs Do? Functionality, Replacement Needs, And More

what do spark plugs do

What Do Spark Plugs Do?

Spark plugs are the piece that provides the spark to ignite the air/fuel mixture that keeps your engine running. They allow your car to move from point A to Point B. They’re a small component that packs a large punch. Without this little piece, you’re not going anywhere! Spark plugs are a common maintenance item, they need to be replaced overtime.

Why Do Spark Plugs Need to Be Replaced?

Due to a Worn-Out Electrode

Overtime, the metal on the electrode (the piece that helps make the spark) will wear away. When this happens, it will either generates a weaker spark, or cause a misfire. If a misfire occurs, raw fuel can get into the catalytic converter, a part of your exhaust system, and cause damage to that (expensive) component.

To Prevent Extensive Damage

To prevent damage, it’s wise to change your spark plugs when the specific vehicle’s operators’ manual suggests.  There will usually be a mileage or year-interval listed, and it’s safe to assume that they should be replaced at whichever comes first.
Even if the mileage is still low, oxidation can cause spark plugs to be seized in the cylinder head, which becomes a very expensive (but easily avoidable) repair. This usually happens to people that have multiple vehicles, and only use one of them once in a while.  While the spark plug itself may be in good working condition, if it becomes locked in place, a cylinder head replacement could cost thousands of dollars.

So, How Often Should My Spark Plugs Be Replaced?

The answer to the question can be found in your operators’ manual. Some spark plugs need to be changed every 3 years or 30,000 miles, and some made from better metals last up to 10 years or 100,000 miles.
The time frame given in the owner’s manual assumes normal operating conditions. You have to be honest with yourself, because only you know how you really drive your car. If you abuse your car with constant heavy acceleration and are constantly at 100% throttle or very high RPMs, your spark plugs will wear away faster then the manufacturer specs state.

Indications that Plugs May Need to be Replaced Prior to Manufacturer Recs.

  •  A misfire
  • Check engine light is on
  • Engine surging or running rough at idle,
  • Difficulty starting your vehicle
  • Decrease in gas mileage
  • Car feels sluggish, meaning the acceleration is not as good as it used to be

Important Factors for Replacement

Always try to replace your spark plugs with the same exact ones that came from the factory. Not only are spark plugs made of different metals, they come in different heat ranges. Your engine can be damaged if the wrong plugs are installed.
If the vehicle is equipped with spark plug wires, those should also be inspected, and replaced if needed. If you’re not sure if the spark plugs currently in your car are the correct ones, a certified technician should be able to pull one of the plugs to check.

Final Thoughts

If you have any doubt about the function of your spark plugs, don’t wait to get to the age or mileage suggested by your manufacturer. Now that you’ve found the answer to your question – “what do spark plugs do,” you’ll understand that if they’re ignored they can cause costly damage.
Go to your local certified mechanic and have your spark plugs inspected if you ever feel there is an issue. By doing so, you’ll alleviate the possibility of costly repairs and frustrating drivability issues in the future.

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