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Discussion Starter #1
Not on the bike. On my Audi TTS Roadster. I got an EPC and CEL last night. Plus experienced massive loss of power.

I pulled the codes below, then planned to replace the plugs and coils as a simple first step, as I have spares from upgrading. Then I found the broken plug.

I'll need to find a scope to see if the broken piece is in the cylinder, and if the piston appears damaged. Outside of that, I'm open to ideas.

33 OBD-II

Trouble codes:
P0300 - Random/Multiple Cylinder Misfire Detected
Active
P0303 - Cyl.3 Misfire Detected
Active
P0304 - Cyl.4 Misfire Detected
Active
P0300 - Random/Multiple Cylinder Misfire Detected
Passive
P0303 - Cyl.3 Misfire Detected
Passive
P0304 - Cyl.4 Misfire Detected
Passive
P0301 - Cyl.1 Misfire Detected
Passive
P0300 - Random/Multiple Cylinder Misfire Detected
Active
P0304 - Cyl.4 Misfire Detected
Active
P0303 - Cyl.3 Misfire Detected
Active
 

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I know you don't want to hear this but, after inspecting with scope I'd try to retrieve broken pieces with a magnet , assuming the pieces are ferrous metal. If I couldn't account for all the pieces I'd pull the head and go from there.

Duane
 

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are all the plugs arced as badly, would think like that paraffin to lube the cylinder and maybe draw out and lifted in to suspension fragments
 

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If you see debris in a scope, try sticking a tube attached to vacuum into the cylinder and watch with the scope to suck them out. If you're lucky, they might even blow out by cranking with the plugs out. It looks like the plug was damaged by arcing, so the missing metal might have just vaporized.
 

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I'm betting that any fragments of a broken plug would be ceramic and wouldn't fall inward because the metal plug portion is still occupying the entry way to the cylinder.
Unless you are telling me that the internals of the plug broke which I have never seen before.
Please confirm.
 

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Obviously the engine was running when this happened and you ran it for some time after, so I'd bet the farm that the piece already got ejected thru the exhaust valve.
 

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ugh. Good luck and best wishes for a positive and mostly painless outcome.
 

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Obviously the engine was running when this happened and you ran it for some time after, so I'd bet the farm that the piece already got ejected thru the exhaust valve.
Yes agreed. Looks like the engine is heavily modified. Are you sure you run plugs with the right heat range?
Inspection with a bore scope is always good. You probably will find some marks on the piston top and the valves.
 

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Discussion Starter #9
I hadn't considered that it may have arced itself into oblivion. I was assuming the piece broke. I'll take a closer look at the stump.

I videoscoped the cylinder and found no stray bits. I'm doing office work now, and plan to videoscope once more before putting back the pieces. I won't be doing any teardown. I'll have a shop do it if needed. I don't have the time or patience. It would take me weeks.

The engine had been missing a beat lately, and I had planned to investigate. So maybe that plug was already failing. The car was running at speed on the freeway at the time of power loss. I already ran it for miles afterward. Damage could already be done. Little I can add if I idle the engine as a test at this point.

The plugs are NGK Iridium BKR7EIX which is one temp range colder than stock. It's the plug of choice with the tune, and the same as I'm going to go put back in right now. Wish me luck.
 

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Discussion Starter #11
They look clean and gray. Maybe a bit lean.

Even at idle, you can still hear the serious missing. Cleared the codes and they're back instantly. I'm afraid my inability to leave well enough alone is going to cost me big time.

Say Ta-Ta For Now.
 

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Maybe you'll luck out and the broken piece is lodged and keeping a valve open.
 

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I'm afraid my inability to leave well enough alone is going to cost me big time.
That is such a common situation.

I have done it and regretted it.

My son has this urge to modify even more the 1989 Mustang GT convertible I bought new and is now his. I keep telling him to leave it alone. I hope he listens to me.
 

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Maybe you'll luck out and the broken piece is lodged and keeping a valve open.
Since it's still missing, that seems likely, or the valve was damaged. You could do a leak down test on that cylinder and see if it sounds like compression is escaping through the exhaust (most likely), the intake (pretty unlikely, but maybe possible), or the sump (although if it's in the rings it seems like it would score the cylinder wall and you see it with the scope). I'm just speculating, assuming the cylinder is misfiring due to compression loss from the debris from the spark plug. If it was running way lean for a long time, I guess it's even possible that it burned a hole in the piston.

I guess the car was taken to a shop, since the photo of it on the flat bed truck. Let us know what they find.
 

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YIKES! :wow: I had one with a very similar look. It was in my SuperDuke when the lands on the piston collapsed and there was a 'dent' in the cylinder head. The mechanic said he thought it was from pre-ignition. Hopefully, you are only experiencing pre-ignition and not something worse.

Superduke has two plugs per cylinder. The main one on the right was missing the tang.


It still ran, although really, really bad even after this happened.


A dimple in the head from something?


I hope your results are different. Mine was taken care of by KTM warranty.
 

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I thought it a very rare event, especially with a quality plug like NGK, always assuming they aren't fakes, but now we have jfink with additional evidence. Fake I/D here ..... https://www.driven2automotive.com/blog/warning-beware-of-updated-fake-ngk-iridium-ix-spark-plugs-how-to-spot-them-august-2017/

Looks like a compression test will help clarify suspicions. I would have expected the piston/rings to be OK as they need to be pretty tough in a turbo car engine, but maybe there is damage to the valves/seats.

Could it just be the coil pack though - here is a UK TT Forum discussion that I thought might help. This looks at the fuel pump/MAF/coil packs when a guy was seeking to answer a similar issue..........
......... https://www.ttforum.co.uk/forum/viewtopic.php?f=2&t=983585
 

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Discussion Starter #17
Fake spark plugs? Who woulda thought? I did source mine from O'Reilly's so I assume they're the real deal.

The UK TT Forum is the best TT forum out there, IMO. There are several, but that one is well populated with active enthusiasts. This little car is way more popular in the UK than in the States. I'm on that forum under a different user name. Thanks for the link.

The performance shop has the car now. They'll know how to deal with the mods if needed. I got a good feel from one owner as we discussed the possibilities. I would love to keep diagnosing this personally. But time and time...and time. It would take way too long.
 

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Discussion Starter #18
Now my wife wants to sell it and get a new Audi S5 Roadster or Cabriolet or whatever they call it. That one is a two-door but a lot bigger than a TT. It's not a sports car at all. She still wants a convertible. It's on OK car, but it looks like a Mom car to me. I would rather get a new Jeep Wrangler. It's a convertible, right honey?

BTW, I won't be modding a car again. It was fun, but I'm over it. Unless we keep this one for now because I'm already down that path.
 

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BTW, I won't be modding a car again. It was fun, but I'm over it. Unless we keep this one for now because I'm already down that path.
If it makes you feel any better, same thing happened to my bone stock 535i (a 2011, but I'm holding onto it desperately, because it's a true manual, 5 Series manuals are unicorns, and I love mine). They covered it under warranty, and it was obviously (Bosch's) fault in my case, but it took them 10 days testing everything else under the sun before they found the bad plug.

Yes, if (and only if) the mod is what caused the failure, and it's provable, there's no warranty coverage, but in terms of what went wrong with your TT, it can happen to a bone stock car. In other words, if you don't mod the car so it'll be covered under warranty, that's a good reason not to, but if you do it to avoid your problem happening on an un-modded car, it might anyway.
 

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I agree.

Quite possibly when you got the code indication the failed (small) piece went down the exhaust stream.
Swap out all four spark plugs and don't forget the anti-seize on the plug threads.
Do a reset on the computer and go for a drive.
Pleas let us know how it has worked out

RR GAry
 
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