A little update from working the last 2 days. I couldn’t get my hands on a “real” leakdown tester so we did a semi-diy leakdown test To see how quickly we bled pressure in the cylinder, using just a gauge and ball valve. Cylinders 1,2, and 4 bled from 90psi to 0psi over 10-14 seconds. Cylinder 3 bled from 90psi to 0 in 4 seconds. Definitely seems to show an issue with rings in cylinder 3 but I would agree I can’t imagine this causing the sputter (especially after a short stint of success today- read on).
Also repeated boost leak test to confirm again to 25psi no issue. Replaced plugs, Ignition coils, and installed AEM wideband sensor (in the bung right off the turbo) with AFR gauge (no HpTuners yet but I think I will get it now). After getting whacky numbers and random red dashes and the same sputter and lack of power we about called it a night. Out of some random will we pulled the battery cable for 15 min to see if we could potentially reset something. I then read reviews about how shitty these AEM sensors can be out of the box for that issue and found out the stock O2 sensor is Wideband and can be connected to the gauge.
Fast forward to today - I hook in the old O2 sensor to the Afr gauge, do my little random look around to double check there’s no loose fuses, connections, intake clamps, etc. Take the car out expecting to get a video of the issue to load here, and low and behold we get 2 good 10 minute runs of zero issue, hard pulls through all the gears. AFR ranges (observed on gauge) 12-13 under WOT .
I was Still a little skeptical at this point so I went out with the Harley gang for a 2 hr ride after this sure as ever the sputter came back halfway through. I got one good video of this, not sure anyone can recognize by noise, but for reference this is what is happening at WOT. Hard to see on the camera but I watched the AFR at 13-14.5 now which to my knowledge is lean for a hard pull but I’m not sure if it’s high enough to cause issue.
As always, appreciate all the help from people a lot more knowledgeable than I here!! Would’ve liked to head down for the Midwest meetup but won’t make it this year. Will have to watch out for it in the coming years.