2 Attachment(s)
2014 Suburban 1500 6L80 First Gear Coasting/Engine Braking Issue
Sorry for the longggg wall of text but I've been dealing with this for a couple years now, searched and searched could never find an answer and just gave up after a lot of failed tuning attempts. Now I've got a bigger trailer which has made my issues even worse so I'm revisiting the issue again to hopefully find a solution or atleast an answer if what I want is even possible. I'm usually pretty good at figuring things out but this has me beat. Other than this the trans works fine and doesn't give me any issues at all.
I've got a 2014 1500 Suburban with a 6l80 & stock 3.42 axle gears that no matter what I do I can't get first gear to work like I want it to in Tow Haul mode without the gear selector being in M1 (Range Select 1st gear). I tuned tow haul mode to hold gears 1-3 until around 3300rpm & 2500 for going into 4th, then downshift automatically 1mph under the upshift speed for better hold back and power when towing or hold back when empty also. I've tried changing the TCC apply settings and I'm happy with how that worked out overall but I still have this issue. I live in a very rural & hilly area and this thing weighs over 7500lbs without a trailer hooked to it, I spend the majority of my time in first and second when towing and have to heavily ride my brakes in town even empty unless I put it into M1 because of this issue.
This tune works great except for the 2-1 shift, it will downshift into first according to the logs but then coasts until you give it gas then the rpms will catch up for a short time then start coasting again almost instantly. It's very similar to how Rzr's with a CVT will do going down hill, but much more consistent. The only way to make it do what I want is to put the gear lever into M and select 1st gear then it acts as I want but then I'm constantly having to fidget with the gear lever. I want to get 1st to work in T/H like it does in M1 if possible, the other gears work just fine and act as I want them to. It did this on both the stock tune and every tune I've made since and I can't figure out why, not sure if its some hidden setting or just torque management stopping me but with it working in M1 I've got no idea.
Any help would be appreciated, I'm really starting to think I just need to throw a set of 4.88 or 5.13 gears at this thing so it's out of first as soon as possible and I don't have to deal with this anymore lol. A copy of my tune and a screenshot from the logs showing what I'm talking about are included below.
Attachment 120492 Attachment 120494