Printable View
Does anyone have any pointers on how I can get my 2015 6.7L torque above 815 ft lbs at WOT? I've found a few things on here of stuff to change and tried them but nothing seems to make any difference. I'm pretty sure my torque PID is calculating right, because when I run my bought time, I can get 1030 ft lbs.
Here's my tune. Attachment 103629 I've changed all the torque limiters I've been able to find.
My guess is you're not getting there because you're running into lambda limits. I moved them to where they will be mostly out of the way, you will have to remove some fuel in your torque to fuel map and you also should go back closer to stock in the timing department IMO, you're definitely hurting spool time. Attachment 103630
Thanks, I'll give it a try tomorrow... I've never had the lambda explained to me in a way that sinks into my hard head... I've messed with it before by lowering the whole table down to .500. The columns have never made sense going from 0 to 2400 mg of fuel... I'm not even calling for enough mg to get into the 2nd columns on the table...
Think of lambda like making dough, if you have water and dry ingredients like flower/yeast we want to mix them so that the dough isn't too watery or too dry. It needs to be just right, well just right is 1.0 in lambda. Just replace "water" with fuel and "flower" with oxygen. Here is how to understand the oxygen to fuel relationship, If we start taking away oxygen the lambda number gets smaller and the mixture is now richer. A lambda value of .80 means there is 20% more fuel than oxygen, and 1.20 is 20% more air than fuel. So why wouldn't we always aim for a lambda of 1.0 if that's prefect? Well sometimes it has to do with our requirements, power gains can be had from having extra fuel available in the cylinder to mix with the air. Even if we spray the exact amount of fuel to mix with all the air doesn't mean it will all mix properly and perfectly. So having that extra fuel ensures we can burn all the oxygen. Other times the ECU thinks it's at a .80 lambda but in reality it's at .95 because the MAF isn't scaled properly for the bigger aftermarket intake. Diesel's can smoke above a 1.0 lambda in certain areas of engine operation because the fuel isn't mixing well. Diesel doesn't evaporate into the air like gasoline, we need the air entering the cylinder to swirl with the fine fuel mist to get a good even mixture. As for the mg axis i don't understand it either, i've just data logged enough to know where it limits and where to make my changes, other than that i can't find any relevance. I would think it'd be total mg for all 8 cylinders combined, including pilot and post injections.Quote:
Originally Posted by bstroked
That's an explanation that finally makes sense to me. I tried the tune and hit 1022 ft tq! Thanks a lot! Those lambda settings must mess with the torque readings and not just cut the top end out. My torque readings seem like they are rescaled.
Don't look at it like the the torque is actually the real torque, in stock form it will be close but the torque number has more to do with your fuel amount being sprayed than real torque. It just so happens in stock form it's fairly accurate, but By adding fuel to your torque to fuel map you throw off the scaling and the torque's accuracy. In stock form the truck had a value of say 130mg @ 1032ftlbs and 2000RPM, now you made 1032ftlbs @2000RPM 180mg of fuel, but now it is hitting a lambda limit at 135mg of fuel. So you are only making 950 ftlbs because to "make" 1032ftlbs it takes 180MG of fuel. By removing lambda limiting it will now spray the fuel amount you are commanding in your torque to fuel table and now make that 1032ftlbs of "torque". If you lower your fuel amount in that same table it'll probably peg 1033ft lbs if no other limits are in the way because the lambda value won't be holding back the commanded fuel amount. Just by rescaling your torque number on your torque to fuel map you can make more "torque" by increasing the torque number at a lesser MG fuel amount. Just look at it as a way to command a fuel amount and not as a real torque number. The ECU limits are all mostly around 1033ftlbs so making the truck make accurate torque will make you hit limits you cannot change and therefore not hit the fuel amount you're wanting to hit to make the power you want to.