Built engine issue

802gt500

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I have a 12 gt500 with a built engine manley rods pistons extreme duty valves timing components upgrade vmp gen 2 67 tb.

Anyhow about 18000 miles after rebuild driving the other day did a wot and then had a skip. cel flashing but no codes read. Drove it home still no code. Started it up again and #4 miss fire. Pulled the plug and it was damaged and closed gap. Took a bore scope and what looks like little marks all over the piston. The plug is intact with no missing parts. Edges of the piston are all there and bore looks good. Something went threw the engine and I cant figure out from where. Did a compression test and its with in 5 lbs of other cylinders.

What do you guys think? Drive it and see what happens? I have put another 30 miles on it and a few wots and all seems to be fine with great power.

Nervous to drive but would like others thoughts.

Thanks

Alan
 

Catmonkey

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Was the porcelain intact? What plugs were you running? Detonation can close the gap if the porcelain didn't break apart and get bounced around in the cylinder. The compression test indicates there's no damage done.
 

MastaAce03

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What Catmonkey said, detonation caused what happened. Get your car retuned for the fuel available.


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69b302

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His 2012 has knock sensors, so unless they are disabled in the tune? Might have gotten lucky and only lost the plug to whatever occurred.
 

Catmonkey

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The knock tables in the factory tune is only set for 1 degree of reduction. Unless his tuner is increasing the value on those tables, a batch of bad gas is not going to save his motor. If you log spark retard and consistently see -1, you may be more in the danger zone than you realize. Here's a table right out of the 2012 strategy.

Knock Table.png
 

DSG2003Mach1

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I would check the other plugs as well and see if they show any signs of detonation. Id be curious to know bad fuel, maybe an injector issue etc...
 

802gt500

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NGK Qty 8 Iridium IX TR7IX 3690 Spark Plug
THese are the plugs that I am running. Only about 100 miles or so. They do seem to be pretty white around the porcelain but they are new plugs. NOthing is missing in or around the plug. The tune was done by bj at vmp. Its a dyno tune with multiple adjustments.
The damaged plug had dings in the steel part of it. Not sure a piece of piston would do that.
Should I go with the brisk plugs?

Thanks for the input guys.
 

Catmonkey

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Can you post a pick of the dings in the spark plug. That sounds like something hard was bouncing around in the cylinder head.
 

802gt500

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exactly my thoughts. Something from the supercharger? Its just 3 impact areas on the plug. I should have take a pic of the plug when it was out.
 

802gt500

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WHat are the real world guys using NGK iridium or the brisk racing gr14ys or brisk gr12s
Always on 93 tune Boost is at 19 on the hit then goes to 16 on top. I am told the cams do this on top end.
 

Catmonkey

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I'm running the NGK iridium. I have run the Brisk plugs in my supercharged F-150 because there were no other colder plugs.
 

einehund

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I'm using the TR7IX'S at 20 psi on a gen2r. Was using them on the m122 at 16 psi for 40k miles. Never had an issue on a 3 season daily driver.
 

MastaAce03

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That’s detonation that closed the plug, there’s nothing else it could be. Which is crazy because those Iridium plugs are tough as hell. For something to close the gap on that plug, it was some serious detonation going on in that cylinder. Did the porcelain on the plug look peppered as well?


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merkyworks

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The knock tables in the factory tune is only set for 1 degree of reduction. Unless his tuner is increasing the value on those tables, a batch of bad gas is not going to save his motor. If you log spark retard and consistently see -1, you may be more in the danger zone than you realize. Here's a table right out of the 2012 strategy.

View attachment 1573760

Interesting, learned something new today!

So if a car is tune does do you consult the tuner to find out what KR strategy was used or can you just download SCT Derive Advantage and view all the parameters of the tune?
 

sleek98

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Interesting, learned something new today!

So if a car is tune does do you consult the tuner to find out what KR strategy was used or can you just download SCT Derive Advantage and view all the parameters of the tune?
If you paid for the tune it’s 99.99% locked and you can’t see anything without logging.

Easier to ask, something like that they likely will tell you.
 

Catmonkey

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Some tuners will write a tune in a format that is readable upon request, some don't. You will not be able to read the latter. But yeah, it's a question I would ask my tuner. I think most don't modify that table and use it while tuning to make sure it's a safe tune. With only 1 degree of retard, good quality fuel is pretty critical.
 

fullboogie

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If you've got marks all over the piston, something banged around in there. It's either parts of the plug, the piston, or a valve. I'd take a look at the ring lands again with the borescope.
 

tvspower

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My engine is also rebuilt 08
Everything outside the engine needed to be cleaned
Example. Blower needed cleaning, new rotors nfront bearing.....this after 60k miles with cams etc...
All the lines were changed , gas tank emptied n fresh fuel.......
Hope you find your mouse......
 

StrayBullitt

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Wow Sounds like you got lucky OP.. do you have Cats on your car at all ? Might be able to pull them down and see if they caught whatever went through. Might pull and look at the blower and see if scores on the rotors to see if something went through it first. Could be a piece of casting material maybe.

Detonation closing the gap ? and physically damaging the plug? that's a new one on me..
 

802gt500

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No cats on the car. I have about 100 miles on it now with no issues. Beat it like I used to a bunch and runs great.

As for detonation closing the gap not likely imo. When I melted 2 ring lands on 2 pistons before the engine build at the track, I drove it 80 miles home and could see the rings from the top through a bore scope. Spark plugs were fine and not closed. no marks on the plugs.
I don't believe aluminum from the piston could nick the plug and leave little dings. Something steel when through.
 

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