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Why Changing Spark Plugs Matters

An oily spark plug.

Changing spark plugs is known to be a key part of routine maintenance, but why?

Without properly functioning spark plugs, you can run into a wide range of problems, from poor driving performance to your car simply refusing to start. Here’s why changing spark plugs is important and how to know when it’s time to have your spark plugs replaced.

What Do Spark Plugs Do?Old spark plugs

A spark plug does exactly what its name suggests: It’s responsible for creating the spark that an internal combustion engine needs to start and run. When electrical voltage is sent to a spark plug, that electricity arcs the small gap between the two electrodes at the firing end, igniting the compressed fuel-air mixture inside the cylinder. Without a spark plug, there’s no ignition. Without ignition, your engine won’t start or run.

What Happens When a Spark Plug Goes Bad?

Over time, soot deposits can form on the spark plugs. These deposits alter the timing of the spark, causing inefficient or unreliable performance. Another potential issue with spark plugs as they age is that the gap at the firing end can widen. Just as the accumulation of deposits alters the timing of the spark, so does a change in the size of the gap. If either of these issues becomes too great, your engine will suffer.

The Benefits of Changing Spark Plugs

Most manufacturers recommend changing spark plugs every 30,000 miles, but you may feel the need to do the job more frequently — or less — depending on your make and model and your vehicle’s performance.

When you change them, you might see the following benefits:

  1. Reduced Emissions and Better Fuel Economy: Spark plugs that have outlived their useful life don’t properly fire and can cause you to use more gas than necessary. Replacing them can improve your fuel economy and reduce your overall emissions.
  2. Smoother Starts: Worn spark plugs often cause slow or rough starts. Getting them replaced should eliminate this problem.
  3. Improved Performance: Malfunctioning spark plugs throw off the way your engine is designed to perform. When you replace your spark plugs, you may notice that your car feels more responsive.

Changing spark plugs is a key part of keeping your engine in good working order. Be sure to get yours replaced (or replace them yourself) at the manufacturer’s recommended intervals to ensure peak engine performance.

Check out all the spark plugs, glow plugs and plug wires available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information about spark plugs, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy Flickr.

Nicole Wakelin View All

Nicole Wakelin covers the automotive industry as a freelance journalist for a variety of outlets. Her work includes news pieces, podcasts, radio, written reviews, and video reviews. She can be found in The Boston Globe, CarGurus, BestRide, US News and World Report, and AAA along with lifestyle blogs like Be Car Chic, The Other PTA, and She Buys Cars. She is active on social media with a large following on both Twitter and Instagram and currently serves as Vice President of the New England Motor Press Association.

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