OMG look at my spark plugs

[Chatchie]

Leaving a gathering 45 minutes away from the house I decided to hit a car was on the way home because salt. I'm with the family and leaving the car wash it's a bit icy so I romp it because racecar. Car falls on its face and get a blinking CEL. I think something got wet because carwash so I hop on the highway and attempt to let it sing but all I get is super rough acceleration followed by more blinking CEL and now an EPC light.

I always have an obd2 dongle in so I launch the Torque app on my phone and get codes for misfires everywhere. Clear them and get back misfire cylinder #1. Figured bad coilpack so I'll swap it when I get home.

I get home and take the redtop off and put an OEM one in, same problem. Pull the plug which was so loose I could have taken it out with by hand with just the extension and omg, the pics speak for themselves. I replaced all 4 as I had new ones in a box for when the K04 went in. All were hand tight.

I'm hoping a price of this didn't break off in my motor but I'm thinking by how dirty the porcelain is it was loose and has had a bad arc for a while. The past 2 weeks I also noticed a slightly rough idle. I should have checked it sooner.

Cyl1 on the left then 2,3,4

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[Stazi]

Dude that porcelain broke of in Cyl 1. Not good.

You need to bore scope that cylinder and do a compression check.


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[Chatchie]

I initially thought this too. It was pitch black out when I pulled the plug and could see the Piston head with a bright light and it looked fine. I do have a small inspection camera that I can get in there but I don't think it's gonna be bad, we'll see tho.

Look how black the plug is all the way up even past the hex section. I think it was loose and that arc was getting bigger and bigger. There's no clean break.

I could be totally wrong but I'll see. I took it out after changing all 4 plugs and it ran strong as ever. Hopefully if anything did break it shot right out at the turbine.

[LionKing]

The size of that would 9 times out of 10, bounce around in the cylinder then shoot out the exhaust valves. I would replace the plugs and recheck for misfire. No misfire, no noises, no problem.

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[mortimersnerd]

What LionKing said. Good chance you're fine.

[Smac770]

If it did already vacate the cylinder, what would such a thing do to the turbo wheel. And would it still be sitting in front of the cat substrate bouncing around? Or is it a pretty soft material that either pulverized or vaporized?

[ELaw]

It may have nicked the wheel a bit, or not, depending on luck. It is probably sitting in the cat, but the parts are probably small enough they're not going to do much damage.

Bottom line if it were me I'd just run it. If problems happen later so be it, but it probably won't cost any more later than it would now, and if you replace stuff now you may be doing so unnecessarily.

[Chatchie]

I'm just waiting on a date from my shop tondo the APR K04 so I'll definitely be curious to see what they find.

My wife had to do like 250 miles today so I told her to take the Audi. She's reported back that it's running super smooth.

[evilpulse8]

Leaving a gathering 45 minutes away from the house I decided to hit a car was on the way home because salt. I'm with the family and leaving the car wash it's a bit icy so I romp it because racecar. Car falls on its face and get a blinking CEL. I think something got wet because carwash so I hop on the highway and attempt to let it sing but all I get is super rough acceleration followed by more blinking CEL and now an EPC light.

I always have an obd2 dongle in so I launch the Torque app on my phone and get codes for misfires everywhere. Clear them and get back misfire cylinder #1. Figured bad coilpack so I'll swap it when I get home.

I get home and take the redtop off and put an OEM one in, same problem. Pull the plug which was so loose I could have taken it out with by hand with just the extension and omg, the pics speak for themselves. I replaced all 4 as I had new ones in a box for when the K04 went in. All were hand tight.

I'm hoping a price of this didn't break off in my motor but I'm thinking by how dirty the porcelain is it was loose and has had a bad arc for a while. The past 2 weeks I also noticed a slightly rough idle. I should have checked it sooner.

Cyl1 on the left then 2,3,4

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My situation is the same as you. Cylinder 1 positive electrode broke off. Spark plug damage identical. It managed to crack my piston. 54k miles on engine.

[Chatchie]

Wow awesome pics. I think I got lucky as I could clearly see the top of the Piston and it looked perfect. How did the car perform with the cracked Piston?

[evilpulse8]

Wow awesome pics. I think I got lucky as I could clearly see the top of the Piston and it looked perfect. How did the car perform with the cracked Piston?

The car idles fine but vacuum is like at 10 inHg with a/c on momentarily turned on with spark plug replaced since I dont want to completely destroy short block. Already ordered a 2016 34k mile engine. I would probably pour a bit of oil in there and vacuum it out to clear off any contaminants bouncing around in the cylinder.

[evilpulse8]

Mine looked fine too until I put the borescope inside lol

[Chatchie]

Dude no you have me freaked out
My wife drove through over 1/2 a tank of fuel today and said it ran fine. Guess I gotta out clothes on and put a camera down it so I'm not freaking out all night.

[Chatchie]

I couldn't even spell properly^. Piston looks fine. There is a bit of oil in there tho. Plenty of vaccum as well. It's actually the cleanest one of all 4 due to all the blow by through the loose plug.

I'm actually luckier I didn't strip the threads in the head.

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[evilpulse8]

I couldn't even spell properly^. Piston looks fine. There is a bit of oil in there tho. Plenty of vaccum as well. It's actually the cleanest one of all 4 due to all the blow by through the loose plug.

I'm actually luckier I didn't strip the threads in the head.

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You got lucky then, I guess I had my bad share of luck. I thought not having a b5 s4 anymore I would steer myself away from having to do engine pulls. I guess not lol

[Smac770]

What scope tool are you using there?

[Chatchie]

What scope tool are you using there?

I've had mine for years and it appears they don't make it anymore. This one looks like an updated model.

https://www.amazon.com/Industrial-En.../dp/B07SX6MCJ3

[Chatchie]

You got lucky then, I guess I had my bad share of luck. I thought not having a b5 s4 anymore I would steer myself away from having to do engine pulls. I guess not lol

Yeah getting lucky with my modded cars isn't something I'm used too. I'm still curious as to what happen. PSA to everyone, check your plugs. Again last night I couldn't believe how loose they were, they were torqued to 25ftlbs when I put them in a few days ago and again they were uncomfortably loose. I went by feel this time and tried to get them a lil tighter.

What's your plans with the car? What mileage and mods?

Mines got over 105k and has been tuned forever.

[Smac770]

Torque spec for the plugs is 30Nm (~22-23 ftlbs). I don't think overdoing that will help much. I don't know what to conclude if the plugs are constantly loosening.

Do you like the scope? Or would you look for something different if you did it again? Looking to get one, but there's hundreds of them to pick from.

[mortimersnerd]

You may want to have your torque wrench calibrated. They can go off over time, especially if they're stored with the internal springs compressed.

[Theiceman]

..as to the route cause .. i do think you are on the right track ... may not be arcing as much as unmetered air getting into the cylinder causing a VERY high temp burn which is burning the spark plug.

A theory i have heard before is the torque is designed to crush the washer in the plug.and seal it against the head ( that is that stomach churning feeling you get as you are torquing it down and feel something give) . if they are ever removed that washer is squished already and may change the clamping force dynamics.

[Chatchie]

..as to the route cause .. i do think you are on the right track ... may not be arcing as much as unmetered air getting into the cylinder causing a VERY high temp burn which is burning the spark plug.

A theory i have heard before is the torque is designed to crush the washer in the plug.and seal it against the head ( that is that stomach churning feeling you get as you are torquing it down and feel something give) . if they are ever removed that washer is squished already and may change the clamping force dynamics.

Ok this is interesting. My electrician buddy who is a freakishly good mechanic and can literally fix anything offered that same diagnosis of an overheated cylinder/melted plug a few seconds after I sent him a pic of the plug. He thinks it melted and didn't break. How clean that piston face is compared to how much carbon was on the others also supports this theory. I'll attach some pics of the other piston faces. Where could this unmetered air come from? Injector seal? Intake manifold leak?

Yeah the plugs definitely squish the first time and lock when re-installing.

The "scope" is just an inspection camera with 15' or so lead. I'm a plumber so I use it to find stuff in walls or peek in heat exchangers.

[Theiceman]

..sucking by the threads of your loose plug..

[Chatchie]

Other cylinders/pistons....


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[ELaw]

Or you could have a bad fuel injector. Not delivering the correct amount of fuel, or a bad spray pattern (or both).

[Theiceman]

Or you could have a bad fuel injector. Not delivering the correct amount of fuel, or a bad spray pattern (or both).

for sure ... something to keep a very close eye on ..

[evilpulse8]

Yeah getting lucky with my modded cars isn't something I'm used too. I'm still curious as to what happen. PSA to everyone, check your plugs. Again last night I couldn't believe how loose they were, they were torqued to 25ftlbs when I put them in a few days ago and again they were uncomfortably loose. I went by feel this time and tried to get them a lil tighter.

What's your plans with the car? What mileage and mods?

Mines got over 105k and has been tuned forever.

I'm planning on keeping the car since it's a low mile prestige sline avant. I'm only stage 1 IE with APR carbonio and h&r springs. I was intending to go stave 3 but not the engine swap drained those funds.

[evilpulse8]

Other cylinders/pistons....


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My other cylinders look like this due to oil consumption.

[Chatchie]

My other cylinders look like this due to oil consumption.

Daaaaaanng that looks like sheet.

This is the reason I went for the B8.5 hoping no oil or tensioner problems. Unfortunately I'm gonna have to do the timing at the same time as the K04/Intercooler as the stretch is past what I'm comfortable with. It's gonna be a nice size bill.