How stable is a OLSD tune?

[Blue02WS6]

I have the VE tuned, and it does fluctuate some, I assume due to temp and humidity, it will be lean one day and back rich the next, so I have a good medium...on more than off...I have two questions, this is not a track car, does the WOT part of the tune need to be closer (as I am sure it will flucuate also) than the 4000 rpm and lower?, (how close do you need to be to be safe?) and wonce you are satisified do you have to keep the WB hooked up or can you remove it, as I would like to remove it if I can.
thanks in advance

[EC_Tune]

If you can keep the AFR on an NA car in the 12.8-13.2 range without ridiculous amounts of spark that cause KR you are good to go.

[Billf6531]

... and what about running STFT in OLSD after tuning the VE to the nth degree from idle to redline?

[WS6FirebirdTA00]

Most of the error comes from the IAT, mine is gone and my car is very stable in OLSD.

[alanderson1978]

Most of the error comes from the IAT, mine is gone and my car is very stable in OLSD.

I've been in OLSD for a few months now, but I haven't been able to log since it warmed up outside. Do you use bias to adjust this? I really don't understand how VE adjusts to IAT like a MAF does.

[WS6FirebirdTA00]

OK, a quick rundown on what I have see:

IAT goes up, fueling richens up, computer tries to "pull fuel" expecting this rich condition. In my car, it over corrects. When it warms up my car leans out with the IAT in place and reading ambient temp.

What the computer does is open and close the IAC motor (in my car) to increase to decrease the AFR. I have tried to go extreme to extreme on the temperature range, and that is the only variable I saw change when I logged, and with the IAC fixed, fueling didnt change on me with an IAT change.

So what is the fix? Pleanty of things. My solution was to take the IAT out and make these little plugs of resistors for various IAT's (thanks to Scott for getting me these values a while back). This way, as the temps warm up, I can put in new plugs to adjust the fueling accordingly. If I need to to go up a half a point I put in a certain plug. I havent determined the equation for it yet (havent done enough testing) but my tune is at 55ºF, if that ambient goes to 80ºF I only need a 65ºF resistor to make the fueling back in line with what it did when it was colder, which may only be a half a point at most. Once again, I have not found actual values yet.

Hope this helps, and this may not apply to every car. I would assume it would move the ETC on non cable TB cars. Although, there may be some acutal injector pulse width changes, I just was not able to see actual fueling changes on the fueling side, only air side.

[S2H]

I set the complex cylinder bias to 1.0 across the board
and go from there..
retune VE for the bias change..
double check fueling needs...adjust bias as necessary..retune VE...

it works well and makes OL SD Extremely stable at all IAT and ECT temperatures

[alanderson1978]

Do you change the filter at all? What's the difference between setting bias to 1.0 in all cells and disabling the complex model? What does the 'Simple' model do? How does bias affect VE?

[S2H]

I dont mess with the filter...just the actual bias

and I start with 1.0 in all cells...and adjust as necessary after doing a little tuning and checking...
get yor VE in line...do an AFR error vs the bias table using Dynamic Airflow in Grams/Second...

disabling the complex model results in a 100% IAT bias..same as setting all the bias to 0 and the filters to 0..

bias doent diretly effect VE...but it does effect the fueling calculation...
the result ends up being that a bias of higher than stock will cause you to have to raise the VE table values..
values lower than stock will result in Lowerin of the VE table Values..

Just remember that they are Just #'s in part of an equation..it doesnt mean that because your VE went up after adding more bias that you are using more fuel..cause you will still have the exact same fule needs as before...its just now your fueling calc will be more acurate and day to day will be more accurate as well

[alanderson1978]

I kinda understand it....I just gotta get out there and fool with it to learn the details.

Thanks again Scott

[S2H]

just think of it this way...
change your Bias to 1.0...higher than stock...probably gonna increase your VE #'s by about 7%-10%...
I'll look around and see if I have any files with a before and after bias change to show the difference...but I dont know if I have them any more..went through a PC meltdown a while back...lost a lot of stuff

[S2H]

this is as close as I can get ya...
Bias on one is set to 1.0 flat
bias on other one is disabled..which is the same as putting 0 in all the cells of the bias table

I didnt have any mod changes....
same car...same everything...consistent AFR after putting bias to 1.0

I fine tuned it slightly but it stayed right around 1.0

[alanderson1978]

I don't mean to jack this thread but I want to be sure I understand this.

I set my bias to 1 across the board, then disabled DFCO and raised my VE table by about 15%. I did a few runs and brought AFR error back in line. IAT's were around 90 today. Now, this summer when IAT's get up around 110-120, chances are my VE will be out of line again. Which way will it go and how do I adjust bias to compensate? I'm running OLSD on the stock OS. Would changing to a SD OS make this any easier?

Thanks

[WS6FirebirdTA00]

well put it this way, my car was tuned when it was 50-55 and today it was about 80 out and from the quick ride I did have, the fueling looked good still, right on spot.

[Dirty Howie]

My car tends to ping as ambient temps go up 10-15 degrees. IAT obviously goes up accordingly. But I have a Dewitts (larger) radiator and my ECT only raises fractionally compared to IAT.

Will messing with this bias help me ?????


DH

[S2H]

I don't mean to jack this thread but I want to be sure I understand this.

I set my bias to 1 across the board, then disabled DFCO and raised my VE table by about 15%. I did a few runs and brought AFR error back in line. IAT's were around 90 today. Now, this summer when IAT's get up around 110-120, chances are my VE will be out of line again. Which way will it go and how do I adjust bias to compensate? I'm running OLSD on the stock OS. Would changing to a SD OS make this any easier?

Thanks

it shouldnt change any...
with bias at 1.0 it will remain very stable...
you may need to fine tune it slightly...but its gonna be within 2% on Extreme(more than 40*) temperature swings

[alanderson1978]

Cool. I'll just leave it alone for now till this winter. Why would bias be so messed up stock? Does it have any effect when running with the MAF?

[jimmypop13]

do an AFR error vs the bias table using Dynamic Airflow in Grams/Second...

Could someone explain how to set this up for me? I know how to set up an AFR % error histo but I'm not sure how to set it up against the bias table.

This thread is a few years old, is this still the best way to run OLSD in any temperature without large errors in fueling?

Thanks!
-Chris

[one_bad_ls1]

interesting... subscribing, I had mine set to 1 already but want to see if its still the best way on my 2barSD

[slammin86]

Woah nice post. I too would like to hear more about this.