Ok my understanding is that HPT doesnt deal well with VE's above 100... so to compensate for that, it gives you the VE offset which lets you work with lower numbers, which when passed theu the offset can equal 100+
so if you have a max VE of say... 120... you would want that cell to read 100... and a 1.2 VE offset.... thus a reading of 70 on the map would really equal 84.. and so on.
In VE tuning (using the methods described in the sticky) does this take into account the VE offset?
I just noticed that the first few passes and reflashes make the most improvements, and then the more you tune after the fact, it seems like you are always overshooting your goal... So just thought maybe it was something to do with VE offset... like large changes dont get effected as much... but when you start fine tuning, that maybe that is more adversly effected by the offset percentage???
should we maybe divide the changes by the VE offset before applying the changes to the maps?
Or is the VE offset already factored in to the histograms?
just thinking out loud on this one...
Did you follow what the person who mentioned the errors in Shifted's original post said?
You "Multiply by %" when you past your AFR errors into the VE tables. After the first pass or two, do it by 1/2 those factors.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
[ion wrote: C2]Did you follow what the person who mentioned the errors in Shifted's original post said?
You "Multiply by %" when you past your AFR errors into the VE tables. After the first pass or two, do it by 1/2 those factors.
Yep i read that and so far have been doing it... but it still is a shot in the dark at best....
I am just trying to figure out what might be the cause of this... so we could all get a lil more accuracy in the tunes, and not just picking different methods of AFR error correction because they seem to work better.
I would like to know the why and how behind it.... not just "this seems to work so i do it"
Why is it that when you do the first big tune, everything is right on... but the smaller the changes you make, the further off it throws things. This is not at all how it should be.... and i would like to look into a solution, not just a band aid.
What does that "mult by %" even do? what is it multiplying by what percent?
I am just wondering if there was a car with no VE offset... if they would have the same issues.
perhaps the answer is as simple as figuring in your offset into the AFR error before loading it into the map. And maybe "mult by %" just kinda comes closer to this and that is why it seems not to screw things up as badly.
It's altering the VE, which enables the VCM to shoot the right amount of fuel in at whatever condition in order to obtain the commanded AFR. It's multiplying the AFR error % to the VE table to compensate for the error to make it closer to a +/- 1% error.
I don't know much about the details of tuning though, or how or why there's an "offset." Shifted is the man to speak with.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
The VE off set just moves the tables up. Allows you to go higher, but limits how low you can go. That is it and simple. This talk about not being able to fine tune the AFR is crap. Never had a problem. Are you using smoothing?
FU Tuning
You are way over thinking this Wade....
To keep this is as simple as I can and without writing a book on it, keep this in mind. The offeset simply raises the values of the VE tables (all of them when you change the offset above or below the set value). Lets say that you start out with a 20% offset. What that means is you are able to modify your tables 20% higher than maxium VE (VE=100
With FI you will achieve higher than 100% when at WOT/boost. Now lets say that you are lean and 120% is not enough. What you will do is raise your offset. Now what you have to keep in mind is that you need to subtract the difference from all your tables before going any further. Lets say you raise it to 50%. When you do that, all your tables are raise 30% higher than what they were at 20%. That means you need to subtract 30% out of all your VE tables before you proceed or else you are going have all your tables off.... Do you see where I am going with this?
Now, if your histograms are set up correct, you will have an error in %. When you mutiply your error by % into your VE tables, you are essentially "tuning" your tables...
P&P Tuning
420.5whp / 359.8wtq
When you go to change the offset save your current file as a new file.
Then open up the old file as a compare file. After you change the offset on the new file you can copy and paste the VE values out of the old file back into the new one so none of them have been changed.
If your tuning manually then you can just change the tables where you need to add fuel. (The ones you needed to increase the offset for)
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
ok, i guess i am confused then as to why we would "add" them in the first place?
now understanding what these things mean, wouldnt we want to "multiply by %" all the time?
it just seems odd to me that we are supposed to ADD the percentages at first... then "multiply by" later.... and then multiply by half later yet....
i would just think that as your tune got closer and closer, your error numbers would naturally get smaller and smaller, so sticking with the same method of correction should yield the desired results.
I am not sure where i read this method... but it was here on JBO. "add first pass, multiply by till your real close, then for fine tuning later on cut everything in half then multiiply it"
I think from now on i am just going to multiply everything. see if that works any better.
Someone should really update the sticky with the proper info.... not everyone is going to read the entire 3 pages to learn the errors.
I plan on just using Mult by % and two two trials, then mult by half % on the third. According to the few on Shifted's thread, they said the part where you "Add" will "Murder your VEs."
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Personally I am not a fan of upping that offset too much. It really pooches the low end, especially when your offset goes higher than the lowest stock values for the motor for low RPM ve and idle. I find that the car never drives the same like that and it's almost impossible to tune it out smooth again.
Sure you can make power under WOT now but fuel economy and general driveability go down the crapper fast.
The offset works but I try to work around it as much as I can before resorting to touching it.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
