Sir, something just occured to me...
Garnet (06envoy) from Sudz has a custom PCMforless tune & I know he tows a ton of stuff with his.
Get in touch with him. He's a great guy, Imma sure he can answer most of your questions by experience!!
He's got the Denali like you do...
I got your txt.
Although I'm not sure what I can do to help. I can just relay my own personal experience.
Denali n DOO said:
As many of you know I have no more warranty and im ready to start with some mods. First thing I'm thinking is the pcmforless tune. Can this tune accomplish better low end and increased mpg and still be good for towing. Is wheel size part of the tune inputs? My summer and winter tires are different sizes. 255-55-18 and 245-65-17. Not sure what effect that would have...
If your interested, this is what I've learned while playing with my own truck.
I also run summer/winter tires and rims on all of my vehicles.
Don't worry about the tire size affecting the speedo. Two reasons.
1) The difference in outside tire size is so small that it doesn't make a difference.
2) The reality is that the dash speedo's are not accurate to start with. I have run four different speed scans and gotten four different speeds from each device at the same time. (While on a cross country trip to NFLD) Speedo, ODBII scanner, GPS and road side radar gun warning all gave different numbers. For the record I think I was travelling at 110kph. Results ranged from 103 to 109 to 111 to 116. My point? The range is big enough that the difference in tire size affecting your speed is smaller than the speedo error margin, so who cares about that level of accuracy when it's almost impossible to achieve in the real world.
Here is the most important thing that you asked for...Off the line performance!
In any tune, PCM4L or otherwise the single biggest thing that affects off the line performance is Torque Management (TM).
From the factory you will have 100% TM. This means that the computer changes the timing so that your engine still revs high, but actually produces less torque than it actually can, thus managing the torque sent to the transmission.
GM does this because at 300HP from the factory we are fast aproaching the limits of what the 4L60 can handle. I've been told about 340-360HP is about all the 4l60 can handle before it starts having reliablilty problems.
If you want go fast off the line, then ask for 100%TM removal. I did.
When you do, PCM4L will give you a warning telling you not to.
I would too.
If you choose to remove 100%TM then it's in no way PCM4L's fault if you blow up your tranny.
I can live with that so I pushed for and received 100%TM removal.
WARNING: If you do 100% TM removal, then you can almost certainly expect a shorter life span from your 4L60.
However that being said, check out my unofficial 1-100kph tests I've posted somewhere here against my wife's TB 4.2.
It wasn't until after my tune, efans and K&N CAI that my truck performed off the line like I thought a 300HP truck should! Which is why I thought about making a run against Harmless!
If anyone asks me, I wouldn't hesitate to suggest 100%TM removal while making sure that they fully understand the risks.
For reference, I've also tried 75%TM as well. That just sucks.... You get great performance off the line until you hit about 4k rpm and then the performance tapers off right when your engine is hitting it's peak HP. That just plain sucks and is fustrating.
As for MPG, I noticed that you have an 06. That's the first year the 5.3 came with DoD.
When you get the PCM4L tune ask for and make sure that you keep the DoD turned on if your worried about fuel economy.
I did. I'm still debating if that was a good idea or not. Now the truck surges when changing from 8 to 4 cyls and vice versa. I figure thats related to a lack of TM. TM would have helped smooth out the transitions.
At first I could feel it surge, but within two weeks, I can't feel it. It's only when someone new gets in with me and they ask about the surging that I'm reminded about it.
I have a simple solution. Drive over 105kph so the truck won't have a reason to drop down to 4cyls.
I asked Kelly when people get the tune, do they keep DoD on or not. She answered most people take it off. IDK, I kept it on and other than the surging I enjoy better fuel economy than my wife's 4.2. My average right now is 13.8l/100km according to my DIC.
As for towing, I pull a couple of Triton trailers. An 7x10 open trailer and a 16' vnose enclosed car hauler.
Because I'm using a ELM327 Bluetooth ODBII adapter and the Android app Torque, I'm monitoring my transmission tempurature all the time.
Here is my real world experience.
I'm towing my 7x10 open Triton empty heading south to Orillia for the spring Burls creek event.
I accidently leave Parry Sound Mcdonalds driving in 'D'.
I watch the temps climb to over 125c in less than 15 minutes. I'm doing ~120kph.
I drop back down to '3' while still doing 120kph.
Honestly the trans temp dropped back down to 97c within five minutes!
I wouldn't have believed it if I didn't see it with my own eyes.
Even towing empty, I run in '3'. Just to keep the trans temps lower. Especially after having 100%TM removed.
As for mods?
You'll get some different opinions.
PCM4L 100%TM removal Tune.
IDK after that.
I have bookmarked and thought long and hard about Stainless Works LT headers and true dual exhaust with x-pipe and all.
But that supposedly adds 30HP.
I'm personally too scared to keep going on mods on my stock 4l60(150k kms) while I'm enjoying 100% TM removal. I know I'm on borrowed time with it now, and if I keep chasing the HP then I'm into a $4k RPM 'Built 4l60'. And I'm not a money tree.
There's a reason why the 400HP TBSS doesn't use our drivetrain and I don't want to be one to find out why.
I think I'm happy with my mods as they are now.
Thanks for reading this far!
Thanks and have a good night!
I'm here all week, until Friday!