LQ4, LS3 MAF, AFR Error WIDELY off... need help

[Brandopatt22]

I have swapped an LQ4 into my 91 S15 Jimmy and are learning how to do the tuning. The LQ4 is stock other than MAF, manifolds and custom intake tubing. I have installed a LS3 style card MAF and have been scaling the MAF Table accordingly to get the idle and general drive ability back. My next step is to work on the VE table but my readings on my table are soo far off i don't trust the readings. Obviously, I'm new to the process so I've made a mistake somewhere. looking for some help please.... My table readings are in the thousands off for my Air Fuel Error, but my AEM wideband is reading in the low 14s.

Thank you for your time and input
- Brando

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[bk2life]

I have swapped

Fail the MAF, tune VE 1st.
then tune MAF
no need for wideband under 4k rpms-the stockers will get you tuned for driving and donw low
WOT or over 4k you use the widebands.

also, if its stock, like stock injctors youd be good, but you always got to verify injector part number, and fuel pressure both idel and driving.

[Brandopatt22]

Its been direct swapped from a 2003 Express. I have failed the MAF while trying to VE tune but the readings I'm getting on the AFR Error table are hundreds off that it just doesn't seem to line up with anything I've seen others have for readings. I was hesitant to multiply by half on the VE table when others only have a 4-8% difference and I'm in the 600+% difference on a unmodified engine.

[bk2life]

dont look at the wideband for the time being

turn on your fuel trims---your 02s are moving, so thats good,
log what the stfts are doing

post up that log

also you have your PE falt across the bored, and to not come on until after 5500rpms

is this computer stock, never tuned?

[Brandopatt22]

Comp is stock not tuned other than my adjustments to get to where i am currently operational. Ok, I'll activate the STFT and log again, PE is already set at 5,500RPM

[twenglish1]

Something has to be off with your math function for the wideband to calculate the error, post the formula you are using, but as stated you are better off using the fuel trims for part throttle/<4000RPM operation.

[twenglish1]

Not sure what is going on here but this is likely your issue:

Screenshot 2025-06-08 170717.png

[Fast4.7]

I tune fuel tables in open loop via wideband. Much quicker and more accurate. Once that is done, re-enable closed loop and adjust the closed loop and 02 target voltages to properly run stoich.

[Brandopatt22]

I got an opportunity to drive the truck today, I turned on the STFT and this is the log of the drive. Having issues with gauge cluster, temp gauge spiking out, seems to be a new issue since actually driving. Wasn't an issue during driveway idles and short around the block runs, but that's expected. temps stayed 92-97 Degrees Celsius (197-206 F) on VCM Scanner, Gauge was 195C. Was playing with the fan activation temps, 2nd stage of 2 fans selection in HP seems to make my relays slap back and fourth like signals are going off on my relay set.

[Brandopatt22]

Screenshot 2025-06-10 213930.png

This is the AFR Err Math I am using from HP

[Alvin]

Someone already pointed this out but it is still wrong. The transform you are using for your wideband is obviously wrong.

In AFR this number will be between say 9 - 20:1 . Yours is in the hundreds. Impossible.

EQ or lamnda will be 0.8-1.2ish

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