[Koz614]

Hi everyone,

First time posting here and wanted to share some borescope images from a cylinder 3 misfire I've been having. Plugs and coils have been ruled out. I'll be checking on compression and replacing the fuel injector but I'm concerned about what I saw when I looked into the cylinder... See images below.. the first two are of cylinder 3, one from the top and the other a close up of the deposits. The rest of my cylinders look like the third picture. All have only 20k miles on them. The timing is odd as well as the misfire started on the first drive after installing the pure 650 before even getting on to the highway.

Mods:
Stage 2 custom Paul Johnson tune
Catless downpipe
Pure 650 turbo
Paradigm engineering intake filter

[Das_Stiggy]

Google image search

I'm not an expert but that sure does look like detonation damage. If the cylinder was running lean from a bad injector this could be the results. The lack of carbon compared to the other piston can also be indicative of this. Detonation tends to blast off carbon.

[Koz614]

Originally Posted by Das_Stiggy

Google image search

I'm not an expert but that sure does look like detonation damage. If the cylinder was running lean from a bad injector this could be the results. The lack of carbon compared to the other piston can also be indicative of this. Detonation tends to blast off carbon.

Really hope not 😮*💨

[RCKYMTN M34OI]

I'd have to agree that looks like piston damage from knock or pre-ignition. Doesn't look normal IMO

[snaimpally]

I had issues with my 2011 335i that ended up being caused by the low pressure fuel pump failing

[Koz614]

Unfortunately the replacement of the fuel injector didn't help the situation.. towing it in for a deep dive. Thanks everyone for the input and I'll continue to post updates.

[Red_sir]

Damn that sucks. Good luck.

[Koz614]

Originally Posted by Das_Stiggy

Google image search

I'm not an expert but that sure does look like detonation damage. If the cylinder was running lean from a bad injector this could be the results. The lack of carbon compared to the other piston can also be indicative of this. Detonation tends to blast off carbon.

Think you were right, I've had a couple professionals bring up detonation without me mentioning it. Had it towed to a reputable shop for some sleeves, forged positions, upgraded crankshaft bearings, and new injectors 🤙🏽

[Das_Stiggy]

Glad to see you're getting it fixed!

[Koz614]

Yep, they said it was detonation for sure. Case closed.