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EQT Talks about Spark Plugs

Posted by Dave Veal on

Hey Everyone,

It's become more and more apparent that spark plugs are a touchy subject when it comes to the EA888.3 powered platforms. What works, what doesnt, what fails, what doesnt, etc.

We're put together this technical article to try and help explain, and guide you in the right direction.

NOTE: These are simply our recommendations and not the end all, be all, law of the land.

First lets start off with the Factory spark plug for your EA888.3 Powered vehicle per the VW Parts Catalog.


ETKA shows us that the 2017 VW GTI equipped with any of the following engines CHHA, CHHB, CJXB, CJXC, CJXE, CJXG, CNTA, and CYFB calls for Spark Plug Part 06K 905 601 B. This part was later replaced by 06K 905 601 D (The NGK Equivalent to this factory spark plug is the PLFER7A8EG, NGK Stock number 94833.)

Research on the Revision D plugs reveals that it was the OE Standard spark plug on 9+ other VW / Audi Vehicles both previous generations and the current. Here's what we know about it.


  • Construction: Laser welded, dual platinum plug (center electrode & ground electrode) with copper core
  • NGK heat range: 7
  • Gap from NGK: 0.031"
  • Gap From VW: 0.032"

That's right, the factory heat range spark plug is indeed a 7 when using the NGK heat rating.

A commonly suggested replacement part for a 1 step colder spark plug has been the RS7 plug, or also referred to as the NGK SILFER8C7ES and sometimes by its stock number 91006.

Early on there were issues with various versions of the RS7 plugs failing, commonly these were from the BERU Manufacturer and it was less common with the NGK Plug but still fairly prevalent.

The most common failure is the ground strap would break off and disappear off into the engine leading to catastrophic engine damage. The ground strap had to go somewhere, and most times it either ended up in the intake manifold getting shared among cylinders, or it would embed itself into one of the pistons. Either way, the results are usually a heavily damaged engine.


The interesting part about all of this is that the failures seem to be isolated to what is called a "Projected Center Electrode" Spark plug as almost no failures have been seen on the NGK Racing plugs that have a Non-Projected Center Electrode as seen below.


For more information Projected Vs. Non-Projected Electrode spark plugs we suggest you read "The Great Spark Plug Debate: Separating Fact From Opinion" by Jeff Smith.

We're going to take a quick excerpt from the article by Mr. Smith to help further explain why we're no longer suggesting Projected Electrode spark plugs

"The way an engine is used has a big effect on choosing the proper heat range. An example might be a dual purpose street/drag car, especially if it uses a power-adder like nitrous or supercharging. For subdued street driving, a standard heat range, extended-nose spark plug would be a great choice, but only if the engine is not called upon to make maximum power. That’s walking a very fine line.

Reeves makes an excellent point. “I wouldn’t want someone to run a projected tip, standard automotive plug in a 1,200 horsepower, 32 psi LS engine because it’s street-driven.”

For high-load, max-cylinder-temperature track excursions, a colder, standard nose or even surface gap plug is the wisest choice."


So you find yourself asking, "But Dave, what does this all mean?"

What it means is, due to the increased rate of failures seen with Projected Electrode Spark Plugs, we are no longer suggesting ANY of them be used in a performance application and we ONLY suggest the use of Non-Projected Electrode Spark plugs.

Maybe your next question is, "What are some good Non-Projected Electrode Spark Plugs?"

Any of the below are acceptable to use for their intended purpose.
For IS20/IS38 at any stage of tune = 1 step colder spark plugs. (Gapped to 0.024")
For Big turbo (EQT Vortex or larger) = 2 step colder spark plugs (Gapped to 0.024")

The information above was lifted directly from our EQT FAQ which suggest all of our customers read. 

"Wow!! Those are $30 each! Is there a cheaper alternative?"

The Short answer is No.

The long answer is, if you MUST run a budget oriented Spark Plug then the Brisk ER12S for a 1 Stage colder plug may be used, and Brisk ER10S for a 2 stage colder plug may be used. 

"What do I do if I've suffered a spark plug failure?"

If you have experienced a spark plug failure similar to the one pictured above, stop driving the vehicle immediately! It's possible that your engine will survive the event, but you're going to want to make sure you find the missing ground strap and remove it from the engine as soon as you can.
Often times the ground strap will become embedded into one of your pistons, this should be fairly noticeable with an inspection camera commonly called a "bore scope." You can try to remove it through the spark plug hole using a mechanical pick up tool

If that doesn't work, further work may be required such as removing the cylinder head. If this is not a job you feel confident performing, make sure to consult with your nearest trained professional. You can also attempt to introduce compressed air into the cylinder with the engine spun over to the intake stroke on that cylinder to try and dislodge it and force it into the intake manifold, upon which manifold removal is required to extract the debris.

If you don't see the ground strap on any of the pistons, it may be in your intake manifold. In which case, removal of the manifold and a proper cleaning is suggested to prevent the debris from entering the engine again.

In the event that you can't locate the ground strap, there is a possibility that it exited out the exhaust valves and may be somewhere in the turbocharger or if you're extremely lucky, its completely blown out the exhaust. But this takes some serious luck!

We suggest that in the event of a spark plug failure where the debris can or cannot be located, that you perform a Cylinder leakage test as well as a compression test to see if your engine suffered any major damage.
Seek a trained professional to conduct these tests.

"Didn't EQT Previously Suggest the RS7 Plug / NGK 91006? Why the change?"

We previously listed the NGK Variant of the RS7 plug as an allowable option for a 1 step colder spark plug. This was prior to the increasing rate of failure seen throughout the community. It is almost impossible to determine if these spark plug failures are caused by;

  • 1) a defective product
  • 2) improper installation
  • 3) incorrect gapping techniques or
  • 4) other factors.

While many customers utilize the Stock spark plug with a reduced gap, or the NGK 91006 (RS7 plug) without issues, it is our recommendation to to use one of the suggested plugs above due to the increasing numbers of reported issues.

Every car is unique, and as such this recommendation should not be construed as requirement for all to follow


Suggested Plugs are also available in the EQT FAQ linked to HERE.

"What is the proper tool to gap my spark plugs?"

We suggest the use of a thread style spark plug gapper that applies even pressure to the entire ground and to verify the measurement with feeler gauges.

If you don't have the exact feeler gauge size you need, you can get creative by adding some smaller sizes together. If you don't have an 0.024" but you have an 0.011" and a 0.013", simple remove them from your feeler gauge set and put them together to make a 0.024"

This isn't your daddy's hot rod and the days of banging plugs against the work bench or floor are over. As are those keychain gappers you pick up from your local hardware or auto parts store.If you're unsure how to use the threaded style of spark plug gapper, we've embedded a video below to show you.


If you have any questions, feel free to reach out to our Support and Sales staff directly.
Sales@EQTuning.com
Support@EQTuning.com

Answers to a lot of your questions may also be found at our EQT FAQ Page, or on our EQT Facebook Group.

 Thanks for reading!
- Dave At EQT
EQT Small


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