Strange short fuel trims, dont seem to match the o2 voltages

[Maxspeed96ct]

This is a swapped vehicle using a 04 GTO engine and ECM, mild cam, aftermarket pump C5 return style filter style, oem gto rail and FIC 380cc injectors.
New delfi primary o2 sensors, long tubes no cats.
We verified 58 psi fuel press at idle.

LTFT are turned off, im trying to tune part throttle and idle using STFT like I normally do and im chasing my tail. STFT in my histograms show very lean, but I can tell its rich by the smell. And when I add fuel the STFT do not change but the car is pig rich to the point your eyes burn and the exhaust is black. .

for example my STFT vs MAF histo show very lean 15+ 20+ , so I make the changes to maf freq % x 1/2 and theres no change in STFT on the next ride. But the car runs worse due to being extra rich from what I can tell.

Even the o2 voltages don't match my scanner math, for example my 02 voltages are in the .8 to .9 range yet the STFT is showing +20 which seems opposite doesn't it?

Same issue with MAF or SD. But I only ran in Closed loop, wasn't able to try open loop and ran out of time.


MAf only Tune and log attached, and a pic of the o2 variation im talking about.
In this log I eliminated most other channels just to make sure it wasn't just my computer being slow.

Even in the chart the STFT bank sae doesn't match the STFT bank 1 sae in My channel list. is that normal ?
Im using the new 4.0 now ( not beta )
pic attached of what im talking about

[TCSS07]

any dtc's, misfires, check for vac leaks? are you sure your injector data is correct?
i found that to be true the mismatch in data - ive have pids in my gauge section not match 100% to my channels lists but i use the histo data to make my changes so its whatever to me so put back the pids you removed
how is the exhaust set up - are the o2 sensors in closed or are you running open headers because that can screw with o2 sensor readings being to close to a fresh air source
making the changes to maf - how much air did you add to the idle section?

[Maxspeed96ct]

No dtc codes or misfire.

The injector data I'm starting to question.

My friend purchased FIC injectors even though I advised otherwise.


They are rated at 36lb at 3 bar 43psi

We have a rail pressure of 58 with the car running using the c5 return filter/regulator so they are actually 42 lb I'm calculating


I intially used the scaled IFR data off the fic website. But the car ran better with 42 across like a true return setup.

Is this the correct method for this style return setup?