I recently installed a WBO2 to help diagnose some ignition issues with my 2g. I found it wanted to sit around ~14.7:1 while I'm cruising and keeping out of the boost. This would jump up into the 15s occasionally as well. Then when I began laying into the boost, my AFR would immediately drop to 11:1 to 10:1 and hold there.

I've done 3 BLTs including one today that have all given me the same result. I'll compress the system to ~20 psi and let the system decompress, it will fall off to 10 psi in about 30 seconds and then hold at 10 psi until I remove the tester. When I do this I cap off the valve covers PCV, and I keep a spring on my dip stick because I will get some air in the bottom end which I suspect is coming through the turbo.

So, my system is pretty healthy in regards to boost leaks, but the system is sort of acting as if I still have a nasty one.

Can anybody think of something that would cause a rich condition under boost, but not show up during a BLT?

Edit: Another symptom that I've just observed, was after each upshift while holding ~10 psi consistently, the AFR would go from around 10.6:1 and jump up to 14:1 momentarily and then return to the 10s and 11s. This happened on a number of pulls I just did.

sounds like you still have some slight leaks somewhere. too me thats a bit excessive of a leak that quickly.

the other issue sounds like either a regulator or injector issue, leaning more toward injectors. maybe one is sticky when the duty cycle gets up there?

The leaning out to 14:1 during and shortly after shifts acts like its something the ECU is modulating almost, would I be better off running fuel system cleaner through them or just swapping each out with another injector?

I should add I've been getting some jerking during low load driving as well.

The thing that makes me lean away from a boost leak being the culprit, is that I've had four engines/cars prior to this one that have never held air as well as this one, and all ran much better. It runs like I have a big hole in the system right now.

that leads me to a fuel system or ignition system issue. most likely fuel with the jerking issue

id check the injectors, pump and filter to be sure, if you have extras you could swap them out, but id clean them and and replace the filter/purge your lines to be sure.

The fuel filter has probably 2k miles on it, recently did a walbro 255 with a re wire. I'll go ahead and pull the injectors today. I should probably mention I'm running some shitty bosch wires right now, napa wanted like 80 for a set of ngk wires so I just ordered a set off amazon.

Edit: I tested injector resistance at 2.7 ohm across the board, cleaned them all out at 20 psi as well without any change. I'll post a log shortly.

Link to the datalog thread: http://www.dsmtuners.com/threads/rich-in-boost-no-leaks.483857/