ya sent you an email stating load the stock tcm tune in because those shift points are likely higher than the stock ECM tune fuels up to. lol
LBZ: Defueling on Lbz
- Thread starter quinton
- Start date
x2... Brad here at Calvin's about has a heart attack if they dont defuel like stock so i have not much choice there even if i wanted to change it...but I 100% agree, I feel they shift perfect from the factory.:woott:
I agree completely with your thoughts on the pulse width. On small tunes, I can leave 80 mm3 and down pulse width alone, but on a race tune, anything above 30 mm3 has to be modified to keep the step between each fuel quantity from being too big. Tq reference on all LBZs I've ever logged maxes out at around 775 ft-lbs, so I make everything above there the same. It usually ends up being the bottom 2 rows. I usually set them at 125 mm3 to make sure they get full fuel. I still have to modify the tq based fuel table to get the defuel just like I want it.
That's the table I'm talking about. Depending on the way the rest of the tune is setup, the second picture would result in no full throttle shift defuel and a very sensitive throttle and very severe part throttle defuel. The third picture is partially what I'm talking about, but there's more to it than just that. All that will do is make sure you are able to get full fuel if the rest of the tune is setup properly. That will do nothing for shift defuel.
Are you guys that are having the problem feeling the defuel during the shifts or just seeing it in logs?
ya third pic was just showing if thats what you meant personally i do 125 in the top three rows and then smooth the rest up to it till its shifting nice depending on the rest the tune..
also if you max the entire table would that make the truck go max fuel soon as you cob it correct?
I'll tell you how I setup that table. I setup that table with it at 0 across the top and 125 across the bottom and then linearly smooth it top to bottom. Then I drive it at various throttle positions while I datalog and let it shift through the gears. I then replay the datalog while I watch the table. If you have cell tracking setup properly, you can see how the tune defuels, where it is before, during, and after the shift. You can then see what cells need to be adjusted, and you can dial in the defuel. I then setup the table so that when the fuel cell tracking moves around on that table, the amount of fuel it pulls is closer to the stock level. I don't completely remove all defuel, but I try to keep it around 5 mm3 or so depending on throttle position and how much pulse that would be. What you end up with is a sort of sloping step going up and down the table that tapers off at the top and bottom. Before I started doing this, there was always a bad defuel at some point in the tune, but now I can run my race tune and it shifts really nice at all throttle positions. Some may disagree, but like Kory said earlier, you do what works best for you.
You can feel it. You probably won't feel it if you aren't running a pretty healthy tune. Most stock safe tunes don't have enough pulse width to cause a problem.
very good josh thanks ill have to do more logging but i havent ever noticed any bad defuel on the lbz and lmm trucks i tuned lol...
now my truck is another story:rofl:
now my truck is another story:rofl:
So I have a question, what gives the quick throttle response of in an LLY, LB7 like the lbz/lmm have? I have experiemented with a few things and helped some. but mine has always been slow to light up compared to 06 and up. I found that it seems to have something to do wit the TLIQ table and but it shifted really rough, like input shaft snapping rough. and havent had time to spend alot of time on dialing it in. just thought I'd ask and see if I can save myself some time. thanks.
see im just the oppisite i can get good response from lb7/lly trucks use the maf tables B0752, B0751, b0728 for llys i usually max b0728 and slowly up the other two till i have the repsonse people want or smoke.. .some want smoke so just max those three tables to 120mm itll smoke alot but it will get full fuel soon as you hit the pedal... but i just try and up those slowly but thats me
Pretty well the same way we tune big builds IF they defuel... I built a map that shows where it is defueling to and them add the correction factor from there.... The changes (in my experience) are very minimal... Think of the ECM as a puzzle piece/directory.
TP>PPDT>TBF limiters>TBF>uS follows mm3 and wherever you have your rail set up.
So if you have 125mm3 of fuel at 436 torque, then have the torque set up for 436 at say 30% throttle... Then you get a tune that does as josh said defuel ect and not to mention the tune is WOT@ 30% TP. The cause (in my opinion) for the defuel a when torque is set up too early ect is because the Allison expects X torque for X TP and when you bring it in way too early you start hitting limiters ect in the trans that we can't see. I like a tune set up so that it brings fuel in much like that from the factory... Just stronger...
That's just my .02... Again, at the end of the day it's all in what the end user wants!
TP>PPDT>TBF limiters>TBF>uS follows mm3 and wherever you have your rail set up.
So if you have 125mm3 of fuel at 436 torque, then have the torque set up for 436 at say 30% throttle... Then you get a tune that does as josh said defuel ect and not to mention the tune is WOT@ 30% TP. The cause (in my opinion) for the defuel a when torque is set up too early ect is because the Allison expects X torque for X TP and when you bring it in way too early you start hitting limiters ect in the trans that we can't see. I like a tune set up so that it brings fuel in much like that from the factory... Just stronger...
That's just my .02... Again, at the end of the day it's all in what the end user wants!