trying to do a little fine tuning with no wideband

[loganlewis]

Ok its been a while since i been on here...I had a 99 4.8 in a silverado. Had it all dialed in with a wideband and had little no positive fuel trims. I took basically the same tune and flashed it into my 2000 gmc with a 4.8. It runs good and all but i have fuel trims that are +8 to +10. I used to use calc.vet to make my VE tables and MAF tables. Now that this truck doesnt have a wideband yet, is there anyway to touch these tables up? I am pretty sure some people can tune lower rpms off of the o2 sensors. Im primarily looking to do this 2000 rpms and under just where i daily drive to try to get rid of the extra fuel being injected. Is this possible? Will calc.vet work without an o2 sensor hooked up or do i have to make other maps? Thanks

[joecar]

Calc.VET uses NBO2 for tuning in closed loop and WBO2 for everywhere else...

if you have only NB then Calc.VET will do only CL (i.e. nothing outside of CL);

if you have only WB then Calc.VET can do everywhere else;

you will have to modify the calc_pid.txt to steer which BEN bid will be used... look at the equation containing the IFF() which is explained in the scantool user manual...

[ in the IFF() you will have to replace the reference to CALC.CL with 1 for LTFTBEN only or with 0 for WO2BEN only ]

[joecar]

It's not really injecting extra fuel...

it is trimming to the correct fuel amount by adding positive trims which are themselves due to fuel being insufficient.

[loganlewis]

Thanks for the explanation. Last time you helped me set up the calc.pid for me. I cant look at it right now and won't be until later until I could. Hopefully I know what I'm looking at!

On a side note, it seems as if HP tuners can just log the stft after disabling ltft and then multiply the tables with percents from their stft table. I see efi already has a stft map set up that's why I wondered if I have to use calc.vet or if another process can be used. Thanks!

[joecar]

It's been a while, post your calc_pids.txt, there have been some improvements.

The LTFT are an accumulation of the STFT, I normally use one or the other but not both.

You can use any process you like...

Calc.VET uses LTFT for CL and wideband for everywhere else, and can be tailored to use wideband only (it becomes AutoMAF);

Calc.MAFT is the reverse of Calc.VET and it too can be tailored to use wideband only (it becomes AutoVE).

See post #29 here: Summary-Notes

[loganlewis]

I gotcha. So I fail the maf, and disable ltft can I use the stft average to adjust my VE table?

Iv even read of some people leaving ltft turned off AFTER the ve and maf is dialed in. Any advantage to that?

[joecar]

Yes, you can use STFT to correct portions of the VE.

LTFT's are long lived, they are learned (i.e. stored in a 4x4 matrix) and referenced as needed.

STFT's are short lived, when their excursions exceed some range they are zeroed and the LTFT's get updated.

[loganlewis]

So why do some people say that they leave long term trims turned off. What's the advantage of it ?

[joecar]

STFT are instantaneous with no memory/history.

LTFT have memory/history, and it takes some time to forget the past and learn the current.

Whether one is better than the other is open for debat

[loganlewis]

Guess I'll leave them off and see how it runs?

Also joecar while I have your attention.
I tried to activate lean cruise in my truck. I put the .caz filr for my os in the calibrations folder, opened the tune and had to option to enable/disable. I enabled, used the same data a member on another site used. And mine isn't activating. The commanded afr is not changing. Don't know where I went wrong.