Hey everyone,

I've recently sold my BT 20th GTI, but I'm still tuning it for the guy who purchased it from me. Im having an issue with the car losing o2 corrections under WOT, and I cant figure out why.

When I say it is losing o2 corrections, I mean B_lr=0 within a couple hundred RPM after going WOT. fr_w=1 at this time, and for the remainder of the pull, actual lambda reads full rich (.75), and target lambda hangs around .78-.79. This is on wastegate spring pressure ~10psi

Things that have been checked-
Fuel pressure is solid up to 35psi of boost (85psi rail pressure)
There are no intake leaks
There isnt a lean condition prior to the ECU dumping fuel (STFT is at ~.90-.95)
MAF output seems to be reasonable
O2 sensor had 3k miles on it when I noticed this, new owner replaced both sensors about a month ago
No exhaust leaks
All emissions deletes are resistored and coded out properly
Injector duty cycle is nowhere near max (USRT genesis II 1000cc and the car is probably putting down 250 wheel at this boost level)
Fuel trims are within 2%
All fueling maps are set to .85 to rule that out

Noteworthy information-
Car is a 2003 AWP 6MT
Original ecu was maestro tuned, something shorted out and fried the throttle drivers (possible o2 sensor)
ECU in the car currently is from a 2002 AWP 5AT jetta (032HF? cant remember) and is flashed with 06A 906 032 HS 0007 software (manual trans)
This issue did not present itself on my maestro ECU prior to it frying itself

I have been doing some reading, (okay a lot of reading) and there doesnt seem to be much info on the topic
I managed to dig up this thread where phila_dot mentions B_lr being inactive if lambda request doesnt fall in certain parameters, but I cant quite make out how that would apply in my situation. All other mentions of B_lr seem to be in reference to tuning partial load fueling via FKKVS/KFKHFM or other fuel correction maps.
http://nefariousmotorsports.com/forum/index.php?topic=2515.0     <-- (reply#8)

Does anybody have any insight into this issue? Any ideas as to what I can recommend as a solution? I cant help but wonder if its an issue with the o2 sensor wiring or the ECU being incompatible with the car for whatever reason. I may need somebody to school me on how and when ecu part numbers can be swapped around, and what software can be flashed onto any given ecu.

edit: Im having trouble attaching logs. heres a link to the log on my google drive. hope thats okay
https://drive.google.com/open?id=1fIgH9-kkWRC_lRwST72DpBIHwwfg4S4e

What percentage is lambda control at a full throttle pull? I'd start looking at your injector calibration. You need to dialed in kinda good with big injectors off 15% can be over fueling by 150cc's what's your long term fuel trim at?  Honestly you need to provide more relevant info. The sci should be fine any 01-05 me7.5 a chassis sci are the same at a hardware level. Although the software version yours using is for a 5 speed and yours is 6. Aside from not having crude in 6th gear and a few other annoyances it's fine.

Long term fuel trims were both very well sorted as calculated. Partial was -.1% and idle was 1.78% when I had him check last.

Log is attached below. Im still working with him on logging at relevant times and good rpm intervals (Im well aware that 1000rpm is hardly a good WOT pull) but he lives in the city so i have to work with what hes sending me. I can confirm that this issue was exactly the same when I owned the car, and B_lr would turn to 0 shortly after going WOT and remain 0 until I lifted. Logs essentially looked the same but had longer intervals where this was occurring due to me being WOT for longer

I still don't see any logs? Also have you tried another ecu and or another software version? I know from first ha d experience There is a broken version of the HS version that has o2/ fueling issues. Try another software version and just post over the basics maf, injectors, etc and see if younger the same result.

pardon me, isn't WB me 7.5 supposed to work in closed loop even at WOT?

So when doing a wot log, watching block 001 shows no percentage correction?

Tune better is the correct answer. If you do, you will find that your correction will reactivate.
There is a limit to o2 reading and within what correction is active.

This is not preventing you from actually tuning in any way. If you are mega rich on boost with 1.00 fr_w, more than likely you have a boost leak or incorrect scaling.

Except there isnt a boost leak, and its rich because the ECU is requesting it. I dont have a request of .85 and actual of .75 or anything. I actually dont even know where the .75 request is coming from, only that it activates as soon as the throttle is wide open and B_lr switches to 0  




Im not claiming to be incapable of error, but can somebody explain this to me a little better. I like to get scientific about stuff like this and narrow things down methodically. Im clearly a little lost, hence the questions. Heres been my thought process while trying to deal with this:

-In stock trim, a wideband (not sure about narrowband) car should not see B_lr=0 on a WOT pull
-The intake has been leak tested up to 50psi (its a simple intake system. Brake booster, FPR, boost gauge, and BOV are the only accessories running from the manifold)
-The MAF seems to be working accurately.

SO, on an otherwise stock tune, with KRKTE and TVUB properly scaled for 1000cc injectors (KRKTE~.034), LTFT of less than +/-5%, boost set well under the MAP limit, and STFT active under normal driving, you might expect WOT fueling to at least be close enough to show high corrections in one direction or another, right?
Well that isnt the case. So I then scaled MLFHM down in incriments of 5% (yes I offset before and after scaling) down to a max of -30%. Still no STFT on WOT. Obviously I'm seeing large LTFT at this point so I reset the MAF curve and scaled down KRKTE instead, ending at .025ish and still didnt see any improvement.

I just fail to understand how this would be an issue of dumping too much fuel and causing lambda regulation to deacativate, or even conversely, not enough fuel causing lambda regulation to deactivate. Prior to this, calculating KRKTE and TVUB has always been very close and at least allowed me to see correction. And for anyone thats wondering, the plugs didnt have any indications of a rich mixture  





As for digging through LRSEB, I'll do my best to attempt that, the german isnt too much of an issue, but I cant make heads or tails of any of the symbols in the function framework. Is there anywhere I can look to make tracing a variable through all these functions actually make sense? At this point I cant tell how any functions actually effect the value of B_lr or any other variable for that matter. Only what functions they belong to and where they seem to be passed on to afterward.

EDIT: Okay, I found the symbol defs at the beginning of the FR. Ill get this sorted hopefully...