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Help, spark plug tip broke inside cylinder.

mk72k15

New member
Location
Socal
Car(s)
2015 GTI
Hey @kraakmo, where did you find the broken electrode? And was your ticking noise only there once you would push the car a little? Also, would the ticking noise increase in frequency as you revved the engine? (Higher rpm?) Where did you feel the ticking noise was coming from? Like closer to cylinder 1 near the intake manifold?
I had the exact same thing happen to me, where plug on cylinder 4 was loose (don't know why) and it came out with a missing electrode, car starts fine and idles fine. Once warmed up it will misfire under load (if I press the throttle more than 40%)
Also did you check your fuel injectors at all?
 

kraakmo

New member
Location
Wisconsin
Car(s)
'17 Golf R
Hey @mk72k15 - I found the broken electrode in the intake manifold (during a time when the ticking noise was not happening). Literally took the manifold off, and as I was rotating it, I heard something loose inside of it. I shook it, and could hear something bouncing around. I opened the faps with my finger, and shook it onto the work bench. Since that point - the sound has not returned (and that was over 5k miles ago).

The ticking noise would come and go. Some times I would start up the car, and it would NOT be there. I'd go for a drive, and it would not make a sound as long as I was not in boost. As soon as I went into boost, it came back and stayed. It was completely in line with the RPMS. The ticking noise indeed did sound closer to Cylinder 1, at the intake manifold. Note - based on the borescope image (and seeing dents on the piston), I firmly believe that the electrode bounced in between cylinders. Since the electrode was found in the intake manifold, then its completely possible that it went from one cylinder, into the manifold, and then into another (insane - I know). The bouncing electrode (sound) actually caused the knock sensors to detect misfires - since I got multiple cylinder misfire, and they all had the exact time stamp down to the second (despite being different cylinders).

Fuel injectors - I did NOT check them (since I found the broken electrode in the manifold). That was my next "step" in this process (I had them in hand, but returned them after I found the electrode in the manifold).
 

Hambone

Go Kart Newbie
Location
Florida
Car(s)
2020 TR GTI SE
Hey @mk72k15 - I found the broken electrode in the intake manifold (during a time when the ticking noise was not happening). Literally took the manifold off, and as I was rotating it, I heard something loose inside of it. I shook it, and could hear something bouncing around. I opened the faps with my finger, and shook it onto the work bench. Since that point - the sound has not returned (and that was over 5k miles ago).

The ticking noise would come and go. Some times I would start up the car, and it would NOT be there. I'd go for a drive, and it would not make a sound as long as I was not in boost. As soon as I went into boost, it came back and stayed. It was completely in line with the RPMS. The ticking noise indeed did sound closer to Cylinder 1, at the intake manifold. Note - based on the borescope image (and seeing dents on the piston), I firmly believe that the electrode bounced in between cylinders. Since the electrode was found in the intake manifold, then its completely possible that it went from one cylinder, into the manifold, and then into another (insane - I know). The bouncing electrode (sound) actually caused the knock sensors to detect misfires - since I got multiple cylinder misfire, and they all had the exact time stamp down to the second (despite being different cylinders).

Fuel injectors - I did NOT check them (since I found the broken electrode in the manifold). That was my next "step" in this process (I had them in hand, but returned them after I found the electrode in the manifold).
How many miles have you logged since you found the electrode? Did you have any visible damage to cylinders/cylinder walls? What about compression test?
 

kraakmo

New member
Location
Wisconsin
Car(s)
'17 Golf R
How many miles have you logged since you found the electrode? Did you have any visible damage to cylinders/cylinder walls? What about compression test?
Over 5,000 miles since I found the electrode. Changed the oil immediately afterwards - no metal shavings found. Changed the oil 4,500 miles later - no increase in oil consumption.

Checking with amazon borescope - No visible damage to cylinder walls. Appeared to be visible damage to pistons 2,3,4 (appeared to be dents).

Compression test results:
1: 190 PSI
2: 190 PSI
3: 185 PSI (spark plug with broken electrode)
4: 190 PSI

All within factory spec. Was the 5psi drop due to the broken electrode or normal production variation? No idea.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Over 5,000 miles since I found the electrode. Changed the oil immediately afterwards - no metal shavings found. Changed the oil 4,500 miles later - no increase in oil consumption.

Checking with amazon borescope - No visible damage to cylinder walls. Appeared to be visible damage to pistons 2,3,4 (appeared to be dents).

Compression test results:
1: 190 PSI
2: 190 PSI
3: 185 PSI (spark plug with broken electrode)
4: 190 PSI

All within factory spec. Was the 5psi drop due to the broken electrode or normal production variation? No idea.
Normal variation. Congratulations 👍
 

Hambone

Go Kart Newbie
Location
Florida
Car(s)
2020 TR GTI SE
Over 5,000 miles since I found the electrode. Changed the oil immediately afterwards - no metal shavings found. Changed the oil 4,500 miles later - no increase in oil consumption.

Checking with amazon borescope - No visible damage to cylinder walls. Appeared to be visible damage to pistons 2,3,4 (appeared to be dents).

Compression test results:
1: 190 PSI
2: 190 PSI
3: 185 PSI (spark plug with broken electrode)
4: 190 PSI

All within factory spec. Was the 5psi drop due to the broken electrode or normal production variation? No idea.
Go buy lottery tickets right now.
 

BrianB1993

Passed Driver's Ed
Location
Massachusetts
Car(s)
2018 GTI S 6MT
I just went to put brisk silvers in at 10k miles and my Plug boot grommets were like slightly melted to the sides of the walls in the plug cylinder lol i had to use a pick and clean it all up. there was not alot melted to the walls but still enough for my socket to get stuck on it and make me take a look
 

Diggs24

Autocross Champion
Location
de plains! de plains!
Car(s)
2015 GTI
I just went to put brisk silvers in at 10k miles and my Plug boot grommets were like slightly melted to the sides of the walls in the plug cylinder lol i had to use a pick and clean it all up. there was not alot melted to the walls but still enough for my socket to get stuck on it and make me take a look
That's sealant.
 

BrianB1993

Passed Driver's Ed
Location
Massachusetts
Car(s)
2018 GTI S 6MT
That's sealant.
AHHH thank you!!! i literally thought of that cuz i inspected the plugs like crazy and the wires and did not see anything missing.. but there was a black ring in the cylinder! You got it perfect.. i kjnow they were the original wires that came with the car so it must have been that. Thank you very much
 

fattypros

New member
Location
San Diego, CA
Car(s)
2017 GTI
Hi all,

Signed up to share what I experienced with a similar situation so far. I know this thread is long in the tooth, perhaps I will create a new post, but this thread helped me so far so I wanted to contribute.

My 2017 GTI Sport with Performance Package is about to hit 70K miles, a lot of highway, it is stock with the exception of the clutch that failed which was replaced with a stage 1 (forget the brand, although it lacks springs and is noisy as all get out) and the brakes and rotors because it was cheaper than OEM.

I had a steady CEL with the 'cylinder 2 misfire' code happen almost 5 months back, but the engine didn't feel like it was struggling or seem out of whack, so I cleared the code with a 20 dollar Amazon code reader and waited for it to return.

It didn't seem to, so I thought things were all good.

Fast forward to a few weeks ago, my car starts shuddering when I put the accelerator down more than slightly in the RPM range of 1500-3000. The work around was either feather the pedal slightly, or upshift to get to the higher RPMs.

I couldn't get another CEL so I wasn't sure where to go, until 2 nights ago. I was traveling for work and finally got a flashing CEL briefly when giving the accelerator a heavier push on the highway. It disappeared but I was looking forward to getting back home to use my cheap scanner to figure it out.

On the way back home from my work trip, I had to upshift and give it the beans on the highway, and the car was not happy, a steady EPC light (does it ever flash?) and CEL flashing, but not stopping, I went back to cruising and feathering the accelerator, and the CEL became a steady light.

Before continuing on, I stopped at Autozone and used their code reader, and what greets me? the 'Cylinder 2 Misfire' code returns! (I forgot the number, sorry).

So I carefully continue, eventually making it home and parking for the night.

The next day, I get to work removing the coils and plugs, starting with cylinder 2 and am greeted with this:
tempImageqat14x.jpg


So I ended up at this thread.

I removed the remaining plugs and the layout looked like this (cylinders 1-4):
tempImage3Ot5J9.jpg


Now on to the cylinders, I am awaiting a 24mm socket to come in with some other items as I was preparing for doing a walnut blasting thinking that may be the issue, as such, I am unable to cycle the cylinders outside of running them for the compression test, more to follow on that. Excuse the pics quality.

Cylinder 1 piston face:
cyl 1 screen cap.png

Cylinder 1 wall:
cyl 1 face and wall screen cap.png


Now for the fun part.....cylinder 2, or known as far side of the moon:
cyl 2 screen cap.png

Cylinder 2 wall:
cyl 2 wall screen cap.png

Cylinder 2 Fuel Injector:
fi cyl 2.JPG


Then we have cylinder 3, another interesting entry:
cyl 3 screen cap.png


Cylinder 3 wall: Sorry, don't have the shot, but it looked similar to all the others.

Cylinder 4 face (I think the lights on the boro were covered in sealant):
cyl 4 screen cap.png

Cylinder 4 wall:
cyl 4 wall screen cap.png


I ran a compression test and the results were as follows:

1: 175 psi
2-4: 180 psi

So cylinders 1 and 4 look pretty good, 2 and 3 look like the bottom of the oven when food falls on it, but the cylinder walls look similar, once I get that socket, I will cycle each piston again and take look at the entire wall.

I replaced all 4 plugs with OEM, put the coils back in swapping 1 and 2, started it up, and everything seems fine. I took it out to the highway, recreating the conditions of more than slight acceleration in that low RPM range, no bucking, no CEL, everything seemed good.

I am still very concerned about where the electrode went, but it's not in the cylinders. I do still plan to remove the intake manifold and move forward with the walnut blasting. I will be sure to check it fully and document that process too.

My luck with cars is never that good, hence why I have decided not to purposely modify beyond stock, no tuning for me. I modified a wrangler with 20k worth of stuff that never got me anything back, so I am content with what I have here on the GTI. But I feel like the broken electrode was product of another issue and not the cause.

When I pull the manifold for blasting, I am thinking about pulling the injectors to scrub the face, but cylinder 2 looked the worst (I can only attach 10 pics, so the injectors are the odd pics out)

The things I don't understand include the following:

-IF the missing electrode was the culprit, why did the engine seem fine in so many other instances besides the slight acceleration? I would think the CEL would be flashing all the time and I'd have more codes like 'hide cylinder'
-WHAT the HECK is going on with the differences in piston face appearance between cylinders 1,4 and cylinders 2,3? I would probably need to remove the head to get in and clear that stuff out, if it's even worth it.

If you took the time to look at all this, I hope something helped you. If you provided feedback, thanks in advance! If you have questions, please let me know and I'll try to answer them to the best of my limited knowledge.
 

fattypros

New member
Location
San Diego, CA
Car(s)
2017 GTI
Those plugs look horrific. As do the pistons on 2&3.
Thanks for the confirmation Diggs.

The fact that both 2 and 3 look like that make me concerned there’s more to this story than the damaged plug in 2.

I really would like to get a better look at those pistons but as this is my daily, engine/head removal aren’t in the cards right now.

I still would love to try and determine how this happened, besides the CEL and clutch as previously mentioned, it’s been smooth sailing for the last 5+ years, I want to try to get another 5 out of this thing.
 
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