[Q] Coil and plug-

[LJS]

I just replaced all of my coils with BERU replacements due to a very slight stumble noted when driving WOT and was wondering if my choice of spark plug was a contributor to the coil's failure....Specifically the resistance afforded by a spark plug and its' affect on over-stressing a coil.
I've been running NGK BKR7E (.028 gap), since early 2003, with various stage II tunes.
I know our ignition system was engineered around a spark plug with 1k ohm resistance and a coil boot with a 2k ohm resistance.
The BKR7E has 5k ohm resistance resulting in 7k Ohm on the secondary side of the coil. Since the system was originally designed for 3k ohm could this increase to 7k, coupled with an increase in boost, over-stress the coil and lead to an early failure.
I was considering changing to a PFR7Q plug which has 1k ohm resistance with the necessary heat range. Other than being 3-1/2 times more costly is this a worthwhile change or am I over thinking this....NO laughing now.....
PS- I'm changing plugs yearly---about 3,800 miles of use.
The coils failed after only some 68,000 miles of use. I don't know if it was one or several coil failures as I changed them all at the same time.
A GOOGLE search on this question didn't yield much....I did, however, learn some stuff about EMI but not much else....

[CELison]

That gap is a little big for stock coils. Try .026 then .024, if that doesn't do it. For what it's worth I ran BR7E's forever and never had a coil fail in 160k miles. I found the BKR7EIX's last much longer though and since moved to those on my R8 coils. I would lower your gap and see what that does. Even do .024 right off the bat. You'll probably get more miles out of them. OEM spec is as low as .015x IIRC. My IX's lasted almost twice as long as the normal 7Es. I was going through BKR7Es every 1k miles @28psi on E with a .024 gap. Finally said fuck that and put R8 coils in. The IX's don't break the bank either. About $55 for a set of 6. But call ahead, most autozones/advanced autos don't have many in stock, if any. I rode my scooter to 3 different stores last weekend, each one only had 2 in stock.

[LJS]

So I've been gaping my plugs wrong since '03- Am I a PUTZ or what.
My first Stage-II tune was a chip and the tuner advised I use the 7E's at that gap-DAMN !
(Those guys are LONG gone--AutoTHORITY out in Fairfax Virginia)
That's most likely the cause of an over-stressed coil-My bad...SHIT
Thanks for the tip on the EIX's--I was aware of them.

[mp3driver]

I run BKR7E's in my S4 at .028 on R8 coils with Meth. To date haven't had a plug fail yet. Now when I ran my stock ignition I had issues all the time. Miss here and there and so on. Good luck with your testing. Hope the lower gap helps.

[JustManson]

Hey Lou! I run at a .024 with an NGK plug. Stock coils Stage 3....

You will more than likely notice a difference right away.


Sent from my iPhone using Audizine

[LJS]

I reset the plugs to .024 while watching the Yankee game-
Hey- we won one....
Damn I work slow---sucks getting old
Hopefully that will keep my coils happy...THANKS for the input guys!

[armageddon-]

I run BKR7E at 0.028 gap without any problems, this with stock ignition system, k04 on 98oct at 1,5bar.

I usualy replace them every 15k km just for peace of mind.

[CELison]

Different cars like different gaps. Hardware, condition of the hardware, tuning, etc all play a role. Plug gap isn’t a cookie cutter value. Just have to find what works for each setup.