Tuning Multiple VE tables

[zq8bob]

Maybe some of the trailblazer guys can chime in here as I think they are in the same boat with the variable cam multiple VE tables... Getting ready to do some VE tuning on my truck, but for the life of me, I cannot figure out how to deal with the multiple VE tables and the cam advance. I can disable the seloniod, but that locks the cam into the high RPM position, making the truck run like crap on the low end, and still leaves me with no way to tune the low and middle two tables (for those who have never seen one, the I-4/I-5 has 4 VE tables.. yes, thats FOUR of them, dependant on cam position...) I'll put up my file when I get home.

[jaronow]

i feel you here zq8bob, i have wanted to touch those tables for weeks. What i think we really need to focus on to be able to tune these VE tables is making some histograms that work with the LTFT and STFT and the different VE tables so we can acutally see what is going on. i think i know how to fully make the histograms now and was going to start on that tonight, but that is how i think we need to go at it. not sure if there would be any other way

[Bill@HPTuners]

the key will mainly be figuring out when it goes into each mode basically...one of these days when its dry out bob we could do some testing with my wideband if you'd like...you just need to get a bung welded in. Maybe Chris or one of the guys can help us figure out what to look for as far as thresholds...is it in * of timing er something else? I saw the VE thresholds but im not sure what exactly they mean to be completely honest nor what to look for still.

[jaronow]

the key will mainly be figuring out when it goes into each mode basically...one of these days when its dry out bob we could do some testing with my wideband if you'd like...you just need to get a bung welded in. Maybe Chris or one of the guys can help us figure out what to look for as far as thresholds...is it in * of timing er something else? I saw the VE thresholds but im not sure what exactly they mean to be completely honest nor what to look for still.

as for your questions, yes the DOHC and their many different positions are controlled by * of timing... there are 4 differnt modes matching the tables and 4 differnt * of timing for when it switches to a different mode

so if all i need is a wideband to see which mode it is in, what would i be looking for when using the wideband, since i am on the other side of the country????

[zq8bob]

I have a wideband...Just need to get the bung welded in. Been so busy with work that I'm actually loosing out on sleep to play with my truck...LOL. As for figuring it out.. I am all about it Bill. Lemme know when, and we can play with it.

Jar..I am feeling you on the Histo's... I have spent a good amount of time trying to even get the LTFT Histos to work.. to no avail. It works, but it only works as a single cell...so theres something I am missing I guess. I really think the VE tuning will help us with our mileage in normal conditions. The way my truck runs, you can just tell they are off..

EDIT: Jar, the wideband is to just monitor in realitime what the A/F is, and not relying on what the commanded values are. That way, we can have an actual view of what the AF is, instead of just what the VCM thinks it is. And if its just timing that controls the cam..then its a simple matter of setting the timing tables to match the low and high end of each area of the cam I would think... but I really have to think that its a combination of factors.. timing, RPM, MAP or MAF freq (or maybe both), and maybe even ECT and TPS...

[Bill@HPTuners]

thats not what i meant by that...for VE tuning its usually a bit more accurate if you use a wideband. It wont magically figure out what mode its in though.

[Bill@HPTuners]

shouldve come to the north jersey meet bob...i showed gerry & Rob how to setup custom histos once you do it once its soooooooooo easy.

[NorthernYankee]

I have been wanting to dig into this too...can I tag along when you guys get together and work on this?

[redhardsupra]

send me a bin and a log, i'll try to build my own histograms, see if we got enough info, maybe just change up my existing VE spreadsheet.

[Bill@HPTuners]

sent

[jaronow]

wicked... thanks for all the help and time you guys have been putting into helping us tune these I5's. i know with just some minor tweeks and removing hte TM my truck is much faster and even the motor sounds better overall

[jaronow]

EDIT: Jar, the wideband is to just monitor in realitime what the A/F is, and not relying on what the commanded values are. That way, we can have an actual view of what the AF is, instead of just what the VCM thinks it is. And if its just timing that controls the cam..then its a simple matter of setting the timing tables to match the low and high end of each area of the cam I would think... but I really have to think that its a combination of factors.. timing, RPM, MAP or MAF freq (or maybe both), and maybe even ECT and TPS...

thanks for the clarification and as for the control of the cam postion it is controlled by cam timing and manifold pressure along with RPM from what the tuning software tells me, it is just way over my head having 4 differnt tables and cam timing's to mess with. i can;t believe how much more complex these motors are than a V-8

[zq8bob]

shouldve come to the north jersey meet bob...i showed gerry & Rob how to setup custom histos once you do it once its soooooooooo easy.

Brother, beleive me, if I could have, I woulda. I work on Sundays. I put in a V-day, but the supervisor who was supposed to run my shift for me on Sunday picked Friday to leave her husband and had to move on Sunday...

Northern Yankee... As far as I am concerned, your welcome to come along... tho I don't have a back seat in my X-cab, so the ride may suck

Supra..thanks a ton for looking at the spread sheet for us. GMT355 guys around the world will raise a glass in your name if it works.... or at least, I know I will.

[NorthernYankee]

Northern Yankee... As far as I am concerned, your welcome to come along... tho I don't have a back seat in my X-cab, so the ride may suck

Don't matter to me

[Bill@HPTuners]

brings back memories of my friends & I coming home from the track with my extended cab s-10...ever time I went wot my friend in the jumper would crack his head against the back window.

[jaronow]

ha ha... what a great story foff... i had a question on these VE tables that i was looking at yesterday. Under the Engine menu, when i click on Fuel Control and go under the Open&Closed loop option, it has two tables that say LTFT boundries and one is for RPM and the other is for MAP... i take it these are the tables that tell the computer which VE tables to reference to right??? if i am right those tables never let the computer touch another VE tables besides the low range table, the mid and high are set to 6000 RPM and 105MAP and higher... and since our trucks shift at around 6000 or, like mine is set at 6175, and the MAP pressure at WOT is only 91or92 at best accourding to my scanner, we never hit anything but the low table which would explain why we run so rich all the time. am i right or am i way off on this here??? either way i finally managed to get the LTFT and STFT histograms to work last night

[EC_Tune]

GM has had the MAP & RPM fuel trim cell boundaries all the way back to 1982. The MAP & RPM boundaries are set up to allow different fuel trim cells throughout the running range (and even some not running ranges in some years>!). They don't determine which VE table you are on. That's another part of the software

BTW: have you been logging the Fuel Trim Cell?
I bet it stays in one cell a lot of the time...

[jaronow]

i don;t know... i just got the LTFT and STFT tables working so i haven;t been looking at the fuel trim cell other than today, it think it has been hovering around 20 or so... what does that mean and waht would i be using this info for and what part of the software tells me which VE table i am on because we have 4 of them for these stupid inline motors and other than my low end the LTFT is around -7 to -20!!!

[EC_Tune]

What GM apparently has done with your Colly is to make anything not idle into one big cell that is constantly adjusting itself.

If you find areas that are constantly re-adjusting themselves (say you are at 50 Kpa MAP & 2000 RPM and the LTFT is -3 and you go to 50 Kpa at 2200 RPM and the LTFT is +6 you could set the RPM boundary to 2100 so that as you transition in RPM you will just change cells and the previously learned LTFT value will be instantly applied when the cell # changes.

I sometimes make the Fuel Trim Cells into one big cell using the settings you have in your Colly. It makes for easier tuning as you are not bouncing between learned cell values when you cross a cell boundary. But if you have a large throttle transition (say deceleration) and the area you are currently in is say +5 and the area you are going into is normally -5, you will get extra fuel that is not necessary until it "relearns" again.

HTH:

EC

[zq8bob]

Getting the Histos working right is something of a pain. Only one works, and it's been something of a pain figuring them out for me with nothing to base off of... Maybe I'll hafta see if I can entice Foff with some free beer and pizza to school me on them one afternoon/evening.

EC... if I am understanding you correctly, your saying that basically we have Zone 1 (WOT) and then everything else is one big zone with no boundaries, including Zone 2 for the dynamic airflow calcs? OR do you mean that other than Zone 1, everything else tends to stay within one zone?

If it's one big zone, then that might explain the HUGE variations these trucks get in fuel milage.... Driving like my Mom, I get about 19 from this thing... another guy on the CF.com with a near same truck is getting 23 driving like he stole it...