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Guide: What spark plugs should I use with my MK7?

Jovian

There are lots of spark plug options available for this platform and some have been more popular than others. Things like one-stop or two-stop colder and the gap on them are things you should try and understand. Depending on what modifications you have made to the car depends on what plug and how close you are going to gap the plug.

In short:

  • If you are stock, stick with the stock plugs gaped to .028
  • If you are running a third party tune (chipped/flashed/piggyback) then you should consult your tuner what they suggest. Each tuner has plugs they tune with or work well with their tuning and your modifications.

What does one stop two-stop colder mean?

  • Spark plugs are rated and organized by heat range. Im going to use NGK’s heat range scale when talking about this as most of the plugs I will be mentioning are NGK plugs. The stock OEM plug for the GTI/R is a heat range 7 plug and happens to be made by NGK for VW. Typically with more added horsepower you will need colder in the heat range plugs. For example the spark plugs in the Audi RS7 are common for cars with just a tune as they are one heat range colder at a NGK rating of 8. When you start getting into turbo’s bigger than the IS20/IS38 you likely will be looking at two heat range colder plugs which would be 9. As the performance of the car goes up the heat range as the plugs goes colder. The reason you want a colder plug is faster heat transfer. This reduces the amount of heat in the chamber. You can read more about this here: https://www.ngk.com/what-is-a-spark-plugs-heat-range-2

What is the purpose of gaping spark plugs?

  • First and most important, no matter what plugs you get you need to check the gap. Even if “pre-gapped” during shipping and handling spark plugs can get out of line and the gap needs to be measured and adjusted. There are many types of spark plug gaping tools out there such as the old coin ones which are not very accurate to using feeler gauges which I prefer much more. Using these tools you place them between the prong (ground electrode) and tip (center electrode) and reduce the gap to specification. The gap you should be using depends on your setup. Stock plugs should be .028 and you should consult your tuner if you are not stock. If the gap on a spark plug to far away will cause longer time to achieve spark or no spark at all. Gaping them closer means a quicker spark but if too close wont be enough spark. Not gaping correctly for your setup can cause untimely combustion or no combustion when its not desired which can be catastrophic. So make sure to follow your tuners advice and gap it correctly.

I keep seeing different types of plugs mentioned like copper, silver, iridium, platinum, and ruthenium. What are the differences?

  • This is really not something you have to worry about too much. You should be using the OEM plugs for stock setups and what ever your tuner suggests if you are tuned. But there are differences between each type that have benefits and downsides and is good to know if your tuner gives you options for plugs. NGK explains it well here the differences between each type of plug metal. As you will read some last longer or have better spark properties and the prices vary wildly between them.

Notes:

  • Plug life varies drastically between the type of metal in the plug, the tune, fuel and how hard/easy you drive your car. It suggested to check plugs with your oil changes.
  • I have a guide on how to change your spark plugs here you should check out.
  • Coilpacks for the MK7’s are pretty good (unlike previous generations) and there is little to no reason to change them for others unless they are broken.