Dan Stewart

Ok, my background in tuning has been with Series II 3800's using PowrTuner. So, tuning Gen III V8's is a little different from what I'm used too. I'm using HPT for this.

Here is my problem and some info:

Attempting to tune VE via STFT (never done this, always used LTFT in past)
Set MAF fail to 0hz, maf still connected
Copied HO table to LO
Turned off LTFT learn
Turned off DFCO
TM turned off
PE disabled
EGR timing turned off, but egr left enabled, egr not connected
232/234 .595/.598 112 cam
LS1 intake
LT headers
ORY
Magnaflow muffler
Lid

Step 1: Went and logged stft's after resetting fuel trims (log attached)
Step 2: Copied stft's from log (avg), pasted special - add to both primary and secondary ve table
Step 3: Flash pcm
Step 4: Logged stft's again

My problem is that the avg stft when I started was extremely neg and after doing a paste special - add, the log shows the stft's extremely positive.

Should I have pasted special - % or % half, instead of - add?

Please have a look at pre-change tune, new tune, pre-change log, and new log.

Comments? Critiques?

1987firechicken

Few things here.

You don't have very many cell counts on some of those values you need to set your scanner histogram to make it so it has at least 50 hits to log a value. You can see this when that mid RPM high map section gradually levels off to less extreme values.

You are also seeing alot of knock retard I would get rid of that first before continuing.

I'd try re-enabling the LTFT and use those to add to your table. I did that first until it was not fueling in big jumps. I then went back when I got a wideband and am currently dialing them in with the wideband with no LTFT enabled.

I'd be wary to even change anything with values that far from 0. Try the LTFT setup first and go from there IMO.

OH and get yourself a wideband to tell what is really going on with your fueling, makes it soo much easier to tune with one.

1987firechicken

Try to to be so sharp with your throttle changes too they can throw off the reading. It should be a smoot throttle transitions not spikey like I see in your logs.

Also make sure your not entering PE mode you can tell by adding the hi-res commanded AF ratio on your table display to see what the computer is demanding as far as AF ratio.

Dan Stewart

Thanks!

Alright, back to ltft tuning for me.....until I get a PLX.

Added a hi-res commanded afr to the charts.

Going to flash VE tables back to stock and try ltft way (honestly, i'm only really comfortable doing this way).

Going to shave a little timing off until the trims settle down.

1987firechicken

Yeah you normally get the VE pretty close before you go to the STFT tuning to narrow it down a little more. With a wideband you'll be almost dead nuts on and you can disable the STFT as well and do it by the % of error in your AF ratio. Just follow the help guide in HP Tuners to tuning it via widebande.

I went with an LC-1 only issue people have is getting lazy with the wiring. Other then that it's spot on and problem free for me. Put it in the shifter boot and grounded everything to a tranny bolt.

edcmat-l1

iTrader: (10)

Here's your problem. Instead of paste special/add, go paste special/multiply by 1/2. Then you won't get the big swing in trims the other way.
Looks and sounds like you're doing everything else right.
I would try and get more cell hits as well.
Start over with your original tune.

edcmat-l1

iTrader: (10)

Nah, long terms take too long. Do it the way I explained using your short terms. You'll be fine.

Dan Stewart

Alright, I'll try it again with the multiply - 1/2.

The whole idea of tuning using STFT's makes sense, just get that "that there ain't how we's is used to doing thangs 'round here" feeling about it.

WB still in the future (got a stall to install, bodywork to finish, exhaust to rework, interior......well, should keep me busy the next few weeks at the least).

edcmat-l1

iTrader: (10)

I use both methods. WB and STFT. The wideband method relies on the accuracy of the WB calibration. Using STFTs, that's what the computer uses to make its calculations and changes. So, why not use it to dial in the VE? You're only dialing in the CL part throttle portions anyways.