First speed density/open loop try

[anniversaryss]

Ok guys first attempt at an Open loop/speed density tune.
Just to be clear this was only idle time.
My nuetral idle is kinda high around 1500 but that needs tuning.
I did notice in nuetral around 1500 the AFR is typically consistent and not to far off stoich or command.
In drive its not bad around 1100 (tune is set for 1100 at that temp). AFR is pretty close to typical with my cam.
Its when the car gets warm and the rpms startt to drop (set for 950) i noticed the AFR will lean out quite a bit 16, 17, 18 depening on rpm and map.
I did notice plotted against my VE as the Rpm drop my VE table gets smaller.
Therefor i assume my VE just needs to get bumped up a little bit in those areas?
Also noticed as it leaned out the IATs were hotter.
Could just be the bias tables need tweaking?

Lt1 24x
234/244 110
Trickflow heads

[anniversaryss]

Added 10%ish to my idle VE. Still lean.

[matty b]

Added 10%ish to my idle VE. Still lean.

You need to read stickies and how-tos regarding VE AFR Error. You cant just haphazardly add fuel and not know why. You set up the AFR error histogram and then you multiply your VE table by the AFR error % to get it correct. If you dont do that, you are never going to get it calibrated properly.

[anniversaryss]

Its not haphazardly. I multiplied by %half of my AFR error and it was around 10-12%.
With my MAF tune things were good. Im just trying to work out VE tuning.
I will take your advice btw and do more reading.
Im just here looking for input. I get the idea of how this works , just need a second set of eyes on this tune and log see if i miss anything.

[matty b]

Its not haphazardly. I multiplied by %half of my AFR error and it was around 10-12%.
With my MAF tune things were good. Im just trying to work out VE tuning.
I will take your advice btw and do more reading.
Im just here looking for input. I get the idea of how this works , just need a second set of eyes on this tune and log see if i miss anything.

If it says you are off by 10% add 10%. If it says you are off 2%, multiply by half. You are nowhere near close enough to do the multiply by half yet.

[anniversaryss]

I kinda figured. Ill try it out

[cobaltssoverbooster]

2004 yukon all stock wanted +15% over stock. i re-sealed the whole top end to verify no air leaks. put the 15% in and it came right into a reasonable error range that i could start copy paste method.
sometimes thats just what they need.

[anniversaryss]

I understand. I pulled a lot of VE down low as per some of the manuals ive read and im way lean.
My AFR error was 25 to 38% off in those areas. So i copy pasted full error and im close to where i started being only like 10 or 15% think it was off the stock tune. Ill have to give it a whirl today or tomorrow.
At least i have a MAF tune i can fall back on if needed lol

[kingtal0n]

with 90-95% cts bias I still get some minor leaning out as IAT heat soaks a bit. I haven't tried 99% but the factory setting of 75-85% at low airflow wasn't enough for my application.

[anniversaryss]

with 90-95% cts bias I still get some minor leaning out as IAT heat soaks a bit. I haven't tried 99% but the factory setting of 75-85% at low airflow wasn't enough for my application.

Would it be wrong to 50/50 the bias by setting it to 1 across the table just as a test?
The way its set up its more bias on the IAT side iirc

[kingtal0n]

The way I read the table, the higher the number the more to CTS bias. So I think 1 will eliminate the IAT completely. I am not sure how much IAT input is eliminated. And so far it seems that is the way its been working for me. But like I said I never tried a 1 yet so maybe you are right there is still some IAT influence perhaps.
I only recently started messing with it. What happened was, I finally completely tuned my VE map and then noticed a big difference when the IAT was 110*F than when it was 80*F. I could literally see the entire "right side" of my scans were lean when the IAT rises, and it would come down when the IAT dropped and rich back up where I tuned it to.

So I started looking for some kind of [IAT effect on air density] table, to eliminate this drift. However upon searching I learned that we do not have access to this unique table (or the formula that it governs it isn't a table maybe) and apparently the real solution is to use this 'bias' feature to hold the fueling based more on CTS than IAT so the IAT can heat soak and the CTS stays down thus keeping the engine rich like you tuned it for instead of leaning out. The problem at first was that there is still some drift if the CTS decides to start getting hot (right now my cruise is 200-210*F but my city driving is 185*F) but its still better than before because now the IAT can stay down while the CTS goes up (highway drive-> high CTS, low IAT) thus the model can bias more towards IAT during high airflow rates (working as intended) and help keep fueling proper for those times as well. It just takes patience. And of course now i have to completely return the VE map also which takes time. Good luck

[anniversaryss]

The way it was explained to me is 0 is all IAT 1 is median and 2 is all ECT (CTS).

[kingtal0n]

by god that appears to be correct! Thanks for the heads up Idk why I didnt see that in the table it clearly says 0 to 2

[anniversaryss]

by god that appears to be correct! Thanks for the heads up Idk why I didnt see that in the table it clearly says 0 to 2

Also if u disable it, supposed to be 100% IAT.

[anniversaryss]

I think i got something here. I modified my VE based on my histogram and its got much better. Still getting a lean issue as the ECT/IAT temps increase. But its not in the 20s like it was. Its 16 to 18. So i think i need to moduify the Bias table but not sure how i should do so.
The car originally started leaning out around 140? when it went to 1.0 in OL it was reading 16s maybe. Now its 14s. I overhsot slightly but im happy its prgress.

[kingtal0n]

I think i got something here. I modified my VE based on my histogram and its got much better. Still getting a lean issue as the ECT/IAT temps increase. But its not in the 20s like it was. Its 16 to 18. So i think i need to moduify the Bias table but not sure how i should do so.
The car originally started leaning out around 140? when it went to 1.0 in OL it was reading 16s maybe. Now its 14s. I overhsot slightly but im happy its prgress.

What I keep doing is adding bias until it stops leaning out completely. Add bias in areas that it leans out too much.

Then go back and re-tune the VE table.

[anniversaryss]

What I keep doing is adding bias until it stops leaning out completely. Add bias in areas that it leans out too much.

Then go back and re-tune the VE table.

Its mostly just idle. My first cell at 0 is .990 or somthing like that. I could try that in my idle cells see how it goes.

[kingtal0n]

Yeah for me especially around idle. I had it at .96 thinking that 1 meant 100% and it was still leaning a bit out (UH OH!?) but then you just awared me about the 0-2 so now I am going to try 1.5 on the next outing

Also I am not sure why but it seems like mileage improved considerably since I enabled the bias feature and adjusted DFCO to come on faster. Might be my imagination though I havn't gone far enough to say for sure.

[anniversaryss]

Yeah for me especially around idle. I had it at .96 thinking that 1 meant 100% and it was still leaning a bit out (UH OH!?) but then you just awared me about the 0-2 so now I am going to try 1.5 on the next outing

Also I am not sure why but it seems like mileage improved considerably since I enabled the bias feature and adjusted DFCO to come on faster. Might be my imagination though I havn't gone far enough to say for sure.

Im gonna try one more thing. I noticed the car leaned out in a few cells that i had not had a lot of hits on. So those cells were badically "smoothed" or "blended" in so maybe i dont have enough VE in those cells.
If that doesnt work then im gonna mess with the bias.

[anniversaryss]

Alright things are coming along.

Turns out the bias is having "some" effect on my AFR but not as much as i thought.

Right now getting my VE in line is where the problem lies.

Its a slow process getting to it once or twice a week but learning is fun and the end result will be gratifying.