My car had it's plugs change at 54k mi. At 60.3k mi it was flashed with a GIAC K-16 91 octane 1 bar flash with overboost to 1.1 bar in cool weather by a local sponsor. At 60.8k mi it developed a mis and flashing check engine light ~ 4k RPM. The sponsor determined it was the plugs, changed the plugs but not the coils since they inspected ok. The car was fine till now at 67k mi. It's doing the same thing. mis and flashing CEL at ~ 4k RPM.

Is this normal? Were maybe the wrong plugs intalled? Could a coil have gone bad?

I ordered a set a coils recently knowing I'd have to do them eventually, I just wasn't expecting to do them so soon. :lol: So what's the verdict on the best plug for flashed car?

Thanks in advance

 

Usually NGK's or Bosch seem to work, but with a flash you may need to gap them differently

 

I am going thru sort of the same thing right now. When the engine is under full load with full boost 1.1 to 1.2 bar, the car is misfiring really bad. This happens at the top of 3rd and 4th, 5th & 6th. My car has stock plugs installed currently. All of the research I have done points to the plugs being gapped too large. I've heard that the increased boost pressure actually blows out the spark causing a misfire. The stock plugs are gapped at 0.06"±0.008" from the factory. Under direction from friends and tuner, I am changing my plugs to a Denso 3245 (PK20PR-P8) Gapped at 0.028". I just picked up the plugs today. Everyone also advises me to change all the coil packs to 997's while i'm in there. I am going to try the plugs first just to see if this fixes the problem. If not, I'll be changing the coils. This gives me an excuse to hang out in the garage.

I am a noobie when it comes to p-cars. This is just my current situation. If any of this info is wrong, please correct me.

 

Your info is good, the gap I would recommend is .026-.028

 

60K miles is a good time to think about changing the coils I think.

 

Well I did plugs today. I removed Bosch FR6's with stock 996 coils. The plugs didn't look too bad, some had carbon build-up while other still showed a little clean metal. But worst of all, all but one coil had small cracks.

So I installed NGK BKR6E plugs with new 997 coils from ebay. The car idles much smoother but I didn't get a chance to drive it. I'll report back once I have more miles on the car.

 

Curious who recommended the use of NGK BKR6E plugs? You're running a flash with higher boost so a colder plug should be utilized. Those are the same heat range as the stock FR6s. The main difference is copper vs platinum.

JH

 

I did mine at ~20k, getting occasional misfires. Noob at the time, so used stock plugs ... Coils were fine so I didn't replace.

Roll forward two years- Getting a misfire code at 5500rpm at WOT, so planning to change plugs. Will use bosch, FR6LDC. Also will replace coils with new 997 coils.

The nice thing about wrenching on a porsche?

Its a porsche.



A

 

Lots of competing opinions on plug heat range... seems 3/4 advocate stock, 1/4 advocate one step colder. Personally woudl only only go colder on a track car that sees a lot sustained of heat or maybe on a very extreme tune with huge turbos..

 

Isn't the FR6 the stock plug?

JH

 

Well after driving the car for a bit, the 4k rpm mis is gone!! Looks like the coils were the issue.

Like Ari said, lots of opinions on plugs. For one I don't mind a copper plug, second, I forgot to order the plugs and I wanted the car running this weekend so I needed a plug locally. And after reading this thread, post #3 and 9, I went with NGK
https://www.6speedonline.com/forums/996-turbo-gt2/99716-spark-plugs.html


Yes it is.

 

Did my coils and plugs at 70k -- different car now.

I had mis-fire and CEL on 2 cyl at WOT - 3500 rpm--nothing since change.

Stock plugs--997 coils. 3 hours. DIY from here. Love this board!

 

Well I didn't like the NGKs after all. I don't know if the gap was too big but the car didn't feel smooth at 1.1 bar. It felt good at 1.0 but not 1.1. So the NGK plugs with a .028" gap are out and fresh stock FR6 plugs are in. Now the car runs like it should.

Also with the help of my assistant/tool girl, I did plugs in 2.5 hrs. :lol: