Interesting. Thanks. I use Wurth CU 800 - aluminum and steel never a good thing. People commonly have a valve cover leak, from reading forums, but I have oil and carbon residue on all the plugs, and there is no oil pooling or anything. Just slightly wet threads all the way up the plug, also coating the washer faces, and the smallest amount of wetness and carbon buildup at the head plug seat. No leaky gaskets. I'm super suspicious about the double wall aluminum crush washer - its function is two-fold - to provide a seal and to help keep the plug from loosening in that environment. I'm convincing myself that the aluminum crush washer is use once. I don't ever recall this kind of issue on my NA cars ... but ...
Filippo
They probably are technically single use, but then again, so are copper/aluminum washers on oil drain plugs and banjo fittings. I've reused crush washers several times on many connections on many cars without issue, including plugs. I used to read plugs at least once a night at the track and went several times a month for several months on the same plugs. The same plugs/crush washers were in and out probably 10-15 times with no problems. Not saying it's ideal, but reusing plugs isn't anything I'd remotely consider automatically problematic.
Thread chaser is "right way" to go, but if I ever have any that seem a bit sticky going in, I'll dab a drop of simple 3-in-1 oil on the lower threads.
If you have fuel pooling around your plug base, then it is either a leaky plug seal or leaky injector seeping fuel there.
That would be my guess. And it would explain any oscillations. Leaky plug seals leaking out air and wasting fuel...would definitely cause oscillations...especially high throttle.
My update: changed HPFP, HPFS, LPFS, changed the BOV vacuume hose to larger diameter than Tial hose. Drove to work this morning...car feels more responsive. But have not pushed her yet. Will do so and then change to stock bmw 3 prong plugs and do the same, then change to NGK gapped to .022 and do the same, then change to NGK stock gap of .031 and do the same and report on response/power delivery.
VT
Just for the record, the only plugs I've been able to get away with the default gap on are the S55 plugs. 95770s had to be smaller (.024 IIRC) and 97506s the smallest at .020 IIRC, to avoid misfires on the same tune...and that's on straight 93. I've always been of the mindset to run the biggest gap you can no matter what, though most people will just gap to .018-.022 and be done with it. Not really a problem, but idling may suffer and those have always seemed like ridiculously small gaps to me.
For now I decided to install the original NGK 95770 plugs @ 18 ft lbs, a bit of CU 800 anti-seize. I gapped to 0.022" and doubled checked all the plugs with a friction fit on the feeler gauge. Everything was completely cleaned with carb cleaner and acetone, including the head spark plug mating surface, male and female threads. I will see if we continue with timing correction issues, and pull the plugs in a bit to see if the oil/carbon issue presents.
I see a lot of forum discussions around timing corrections with little conclusive evidence - from "it's just normal" to #5 has significant corrections because of (several reasons given). Carbon deposits where I mentioned is not good news ... and I would not be surprised if most people never noticed it.
Filippo
Some are normal obviously, but more often than not, I think it's tune, change in fuel, temps, etc. Not sure what tune you run, but seems many people these days don't tune themselves or even pay for custom. When running OTS maps, you're stuck with what they give you. Target too much, DME will take out what it doesn't like. Many are really opposed to reducing timing target and simply dumping E85 or adding meth to keep it, but since I run pump only, makes more sense to me to drop target 0.5-1° if it keeps the DME from pulling 3° out instead (if other all adjustments didn't stop it). Either way, I personally wouldn't ever expect plugs/gaps to do much of anything to alleviate timing corrections.
... I'd like the possibility of getting a bit smarter on all of this. And I'd like my timing corrections to drop - I'm pretty sure my setup is at fault.
