68SS98Z28

I would like to hear other's thoughts on this, did i miss something?

I installed SLP performance pack for the intake (lid, bellows, and bottom breather). I dissabled MAF and copied high octane table to lo octane, reset LTFTs and logged LTFTs with HP Tuners everyday for a week. All STFTs were plus/minus 5 after one week (it was raining on and off all week) and the LTFTs were slightly negative on the low load, low RPM side (none more than -5) and in the mid RPM/Load range most values ranged from 7-12 positive.

So on Friday i took the data from the LTFTs and STFTs and summed them both, and added them to the VE table. I hand smoothed a few numbers up and/or down (mostly up to smooth for cells i never hit on the high RPM side) for spots on the table that i might have missed with logging. Result was the low load/RPM corner of the table was largely untouched, mid range was increased 7-10 and i smoothed up from there. At the higher load area i left the existing trend of the stock table where VE falls off at the highest loads. No other change to stock program.

I flashed it Friday night and reset the LTFTs (i think reflashing does this but did it anyway since i'm new at this) and went for a short spin. Right off the bat most of the STFTs were plus 15-25 with one or two cells as high as 30. The car ran a little rough (though really not that bad) and started learning the FTs within minutes the LTFTs were popping up in the teens and twenties. Since the car isn't running too bad i decided to leave the program and see what the LTFTs end up at. I checked retard and was getting a few degrees at high RPM (this was the same for stock). The car feels pretty normal except under changing driving conditions i occasionally hit a not-oft-used cell and it surges a little or bogs a little. I haven't tried WOT but at about 75% TPS the car accellerates smoothly but seems a little slow until i get to 4000 RPMs or so and it seems to take off. I didn't mod much past 4000 RPMs so it seems this is were it's returning to a closer to stock program and then getting some power back.

What did i do wrong? This is my first try but i did a lot of research and this approach seems consitent with what most are recommending starting off. It seems like i went in the wrong direction, like i should have subtracted the trims from the VE table?

Your comments are appreciated.

Paul

LoWeLL216

iTrader: (1)

Sounds like you did things correctly, but you might want to check your math again just to make sure. I'd also recommend using a spreadsheet if you didn't in the first place. Just remember the formula:

Correction = LTFT's + STFT's (if they're +-5)

Your trims weren't all that off to begin with so you might want to only use like a 50% correction so you don't overshoot or end up just chasing minor corrections around. I also wouldn't correct any cells that are already -5 to 0.

joecar

Paul,

Hi there.

Did you straight add the LTFT+STFT to the VE table cells...?

If so, then this is the problem.

You should be adding the percentage of what's in the VE cell to the VE cell.

For example...
say your LTFT is +15%, then you multiply that VE cell by 1.15;
say your LTFT is -15%, then you multiply that VE cell by 0.85.

68SS98Z28

Joecar, thanks for the info--That was one thing that wasn't clear to me from all of the reading i did was if i was supposed to do a % correction or add them since as i understand the table is a percent and the LTFTs are percent. I read several that indicated you should straight add, going so far as to recommend copying the values and right clicking and paste special-adding.

I did use a spread sheet. It'll be easy for me to change to percentage. Here's a question back at ya--in the case of straight adding them rather than doing the percentage, i should be adding more (absolute numeric) to the table, so shouldn't i be getting negative trims to correct this??? Why the big positive trims when i didn't see them with the stock program?
Thanks!
Paul

LoWeLL216

iTrader: (1)

I disagree with this. You can do a direct copy and paste from table to table. It is a straight add and not a multiplication.

Example: VE Cell is 50 (%)
LTFT = +5 (%)
STFT = -1 (%)
LTFT + STFT = Correction
(5) + (-1) = 4 (%)
New VE Value: (50) + (4) = 54 (%)

Not (50) X (1.04) = 52
This works, but applies 50% of the correction instead of the sum of the trims. Its a good way to keep from overcorrecting. Nothing wrong with it, but per the formula it isn't correct.

RedHardSupra

iTrader: (1)

try this:
http://redhardsupra.blogspot.com/200...dsheet_03.html

ringram

Lowell, its 5% of 50% not 5% of 100%, so Joecar is right.
5% of 50% is of course 2.5%.

Anyway as he says if he added fuel his trims should have gone -ve, so I think something else is wrong.

joecar

Paul,
You're right, as you add more to VE table, the trims should go down.
As ringram said, something else is wrong.
Doing the SD tune should have set you up rich, so when you alter the VE table you get leaner, converging on zero trims.
A sanity check is required, reflash your tune without the LTFT+STFT correction; do you get the original results:

68SS98Z28

JoeCar and others who are helping (thanks!):
I went back to the stock flash and it was even worse (some trims over 30). So i looked at everything again and realized when i used the stock program with only the VE table edited, i didn't set MAF failure to 0 or copy the high octane table to the low octane table.

I went back to the stock program with the VE table edited, changed MAF failure to 0, copied high octane table to low octane table, reset the LTFTs (do i have to do this? It seems like they should be reset when i flash the new program, but judging by the histogram they are not...) I was only able to drive it about 5 min (had to get to work) but it looks much better, i haven't hit many cells yet so i'll let you guys know when i do.

BUT, since i have a few people's attention on this thread, i have a few other questions...

But i thought i would start a new thread. Thanks for all of your help! and i'll report back here when the LTFTs settle down.

Paul

68SS98Z28

JoeCar and others who are helping (thanks!):
I went back to the stock flash and it was even worse (some trims over 30). So i looked at everything again and realized when i used the stock program with only the VE table edited, i didn't set MAF failure to 0 or copy the high octane table to the low octane table.

I went back to the stock program with the VE table edited, changed MAF failure to 0, copied high octane table to low octane table, reset the LTFTs (do i have to do this? It seems like they should be reset when i flash the new program, but judging by the histogram they are not...) I was only able to drive it about 5 min (had to get to work) but it looks much better, i haven't hit many cells yet so i'll let you guys know when i do.

BUT, that brings up another question...when i'm done with the VE table and return to MAF function, will the trims go high again? Will it matter? What are the pros/cons of SD?

Also i have some thoughts/questions regarding the VE table but i thought i would start a new thread, hope to see you there. Thanks for all of your help! and i'll report back here when the LTFTs settle down.

Paul

joecar

Paul,

Phew, that's a relief, that's good news.

Once your VE table is dialed in, you use this to dial in your MAF table.
This is what I'm messing with [and learning] right now, in between my crazy schedules.
It involves similar principle, using LTFT's to converge MAF table.
Search the forum for this, some people have comments about this.

Regards
Joe

68SS98Z28

Well, the STFTs are nearly all between -5 and +5 and the LTFTs just seem to have one patch that is still lean, from 1200 to 2400 RPM between the 60 and 75 pressure lines. These values are all between 5 and 10 while the STFTs in this patch are all between -5 and 2.

This was achieved with the straight add by the way, not the multiply by a percentage for what it's worth.

Hopefully once more and i'm done with the VE table. BUT, what next? Some have said the MAF should be next but others have said if you have the automatic tranny don't F with the MAF. Should i look at Advance next? I have some NR at flow rates above .42 and i'm running the high octane values on the high and low octane tables. I only put high octane in the car, is this NR OK or should i be trying to eliminate it? The car is intended for street (it's my daily driver) and autocross (not as interested in drag though i might make a few passes before they close the strip here in Hawaii next month). With this use in mind i was under the impression that a lot of torque could be gained by advancing the timing in the low and mid RPM ranges since that is mostly where the car will reside.

Thoughts?

Thanks!
Paul

ringram

The odd tick of KR is hard to get rid of altogether.
It depends on what you are getting. Sawtooth KR is bad.