2005 GMC Yukon XL stock - flex fuel - Just getting nervous - VE tune

[TinyDancer]

VE Tune 1 Log.hplGMCEdit2 VE tune.hpt


L59 Flex Fuel, Returnless. Truck is stock other than a 14 bolt AXN rear end.

I have followed several guides - elected to go STFT only for VE tuning. Wideband is planned for next month (family and a business, truck fun comes last) but I got impatient to start messing with things. I'd just like another set of eyes to let me know if

1 - I am doing this right

2 - I am not missing any obvious sensor issues.


- I know I don't have enough data points. I have a two hour drive scheduled for tomorrow that I expect will get me all the info I need.

Thanks! Yall are awesome. I've built cars all my life and I have learned more about combustion in the last two weeks than I ever knew.

[bk2life]

i like using stft+ltft for the tables, but your st works just the same.
Dont go too high int he rpms, you dont have a wideband and you cant tune that high.
Also if you are logging spark reduction you have some timing being pulled.
Get your VE +-3 and youll be good to go on the numbers. You can try fighting it to get it closer, but, a street driver has all sorts of things like cold air, hot air, rain, elevation all sorts of stuff that will keep moving the VE around. Once youre close, which you already are, set it for CL and dial in the maf. Post up that log also.

[TinyDancer]

Thanks! Yeah I noticed right off that it's pretty close. Really just doing this as an exercise to get my feet wet. The truck runs great for 280k miles. The timing thing came as a surprise. I did quite a few unmodified tune logs and never saw spark retard before today. It was really muggy today though. I'm getting *slightly* different trims across banks here and there. Probably nothing to worry about but I'll be doing all the injector O rings this weekend

[bk2life]

I'm getting *slightly* different trims across banks here and there.

and you always will on a street vehicle
you can never get it 100% perfect
Thats why we have closed loop and O2 sensors to keep it all in line