going dead lean over 4500, 2 bar OS

[Grr]

I am having serious issues tuning this lean spot out. I cannot find the problem and would like some help. I have 3 different logs and the tune i am using, as you can see, the O2 mV drop off completely over 4500, regardless of pressure. here is my combo
87 Buick GN
02 silverado 6.0L, LQ4
stock engine
224 lunati cam
Pro Prod, typhoon aluminum intake
65# mototrons
home made headers
single Borg Warner S475 turbo
running on E-85
And yes i am just using narrowbands at the moment, as i havent gotten a new wideband yet. So, please give me some pointers on what to change or see if theres any nice tweaks i can do to make the tune better as a whole. I am currently going non intercooled, hence the very low timing for now. Other than that, it runs and drives fabulous, and responds very well under boost, below 4000rpms anyway. thanks
Gary

[Bill@HPTuners]

you really need to consider logging commanded afr in the scanner. Those scans only allow us to speculate & nothing more meaning you'll get little out of a thread like this other then the typical "get a wideband" answer. Which even I will say it...get yourself a wideband.

[WS6FirebirdTA00]

you do realize that the STFT are pulling 20% fuel at WOT in low RPM right?

like Bill said, get a WB. I dont see how people go WOT without a wb and any big mods to get air in the motor.

[Russ K]

Looks like the Maf is unplugged instead of being disabled, the IAT is -39*C. And why is the stoich at 13.88? This should be 14.68.

Russ Kemp

[Bill@HPTuners]

he probably set stoich lower because of the E-85 gas & things he's read in adjusting for it...I was going to mention it till I saw he even mentioned E-85. He should understand that changing stoich changes every other fueling table basically.

[Russ K]

This is a pic of the Stoich table 2006 Corvette. Looks like Stoich for 85% alcohol is slightly leaner than 9.69.

Russ Kemp

[Grr]

ok, yes i did change the stoich setting lower, for the fact that i have been trying differnt things on this. This last time i grabbed up a 2 bar file from another tune that was for a rear mount on a vette, so i used that table and richened it up using the stoich value till it was close, which, i assume would be the right thing to do since alky has a lower stoich point anyway.
This still isnt fixing any of the problems. And yes i know its pulling 20% fuel. BTW, buy a wideband, no shit, but im bulding this car while in college and on a budget, theres a reason its taken 2 years to do this.
Anyway, I had purposely fattened everything up to try and get a decent O2 reading out of it, but it not working. I even pulled the charge pipe off and its doing it N/A as well, just popping and misfireing around 4500rpm.
So, Ignition? Just put in new plugs friday, a NGK TR6 equivalent, in an autolite brand. I logged commanded AFR as per your reccomendation, thank you, and it was commanding 11.55 on the logs i posted. I am damn sure its not out of fuel pump, for one i made more power than this with the v6, and if you look, its at 11.5 200rpm before it goes lean. SO, looks like ill pull a few plugs and see what they look like. I am kinda curious that it could just be bad plug wires honestly, but wouldnt that show up as a rich condition wouldnt it? I never had these kind of problems doing the 1 bar SD on my GTO last year.
Russ K, thanks for that table BTW, i was curious about that

Gary

[Grr]

ok, did some more logging, hopefully this will help some. I think im out of fuel pump, but it still seems like the 02's are just shutting down about 4400. heres another log so you can see whats going on. BTW i switched to regular gas to get a little more out of the fuel pump, not ignition related, all plugs were cherry, gapped to .030". help?
Gary