WTF happened to my plug

bananas · 11-09-2010

Pulled plugs last night to do a compression test and found this. Compression was 160 160 115 160 and 175 175 135 175 with a cap of oil, so I am thinking some of the plug went out the exhaust valve.

Detonation? Meltdown? The other 3 plugs look normal. When this happened, I was running a measly 22 psi on 92 octane + meth.

Any thoughts?

A//// Guy · 11-09-2010

Looks like it got a bit toasty in there.

**Halon** · 11-09-2010

By the looks of those pictures, how did you even fit one of those massive things under the hood?

Other than that, some more info might help. Is this out of an A4 like it says under your name? What kind of plugs are these?

bananas · 11-09-2010

Yes, Bosch F6DTC tri prong copper electrode, A4 1.8T
I am pretty sure it must have happened at BIR while on the road course. I have been running 30psi on the street, but turned it down to 22psi for BIR. My injectors are Siemens 60lb and were purchased as "flow matched", but I never verified them myself... maybe I should get them tested.

DoughtCom · 11-09-2010

Do you have a professional tune? EGT Gauge and or wideband? That's pretty crazy.

bananas · 11-09-2010

No EGT probe. Self tuned, but it's a Motronic always-closed-loop wideband tune, so it should have been pretty safe

Gravy · 11-11-2010

I would have to say your tune isn't "That" safe. For whatever reason that plug looks to have melted from getting too warm.

blackawdtsi · 11-11-2010

Ah, the lost art of spark plug reading.

http://www.ngksparkplugs.com/tech_su...qs/faqread.asp