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Not impressed with duramax towing power

gonefishin

gonefishin

1/2 ton status
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Apr 22, 2010
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Location
Carthage tx
So last week i towed my blazer behind my 2015 lml. The trailer weight 4000 lbs and it had my blazer and 2 4wheelers on it. My blazer is on tons and ag tires. Not sure what my blazer weighs, but i am thinking total weight i was pulling was around 10k.

I live in southeast Texas and the hills are really small. I set cruise at 75 ( that is the speed limit here). There was one of the hills the truck kicked down to 5th gear and it was still losing speed. I put it on the floor and it lost speed down to about 65 by the time I got to the top. It also only got 8.3 mpg all highway. Does this sound normal?

I am kinda disappointed with my truck and the amount of power it has.
 
Doesn't sound normal to me..
My older brother had a 2002 3/4 ton HD 4x4 with a Duramax and Alison trans,that pulled a fully enclosed 20+ foot car trailer with many different vehicles and if anything,he had a hard time keeping it from creeping up to 80+ mph...hills didn't bog it down much either,and he hauled his race car in NH over many steep ones...not sure what mpg he got,but I doubt it was less than 12 mpg..
 
gonefishin said:
So last week i towed my blazer behind my 2015 lml. The trailer weight 4000 lbs and it had my blazer and 2 4wheelers on it. My blazer is on tons and ag tires. Not sure what my blazer weighs, but i am thinking total weight i was pulling was around 10k.

I live in southeast Texas and the hills are really small. I set cruise at 75 ( that is the speed limit here). There was one of the hills the truck kicked down to 5th gear and it was still losing speed. I put it on the floor and it lost speed down to about 65 by the time I got to the top. It also only got 8.3 mpg all highway. Does this sound normal?

I am kinda disappointed with my truck and the amount of power it has.
Click to expand...

You might be over 10K, you might be surprised how heavy these trucks get when you start adding tons and big tires. Nevertheless, you shouldn't have an issue pulling it. I know these days everyone expects their diesel to pull 80 mph up a hill with 20K load, but the whole point of those new diesels is that they can do it.
 
and if you don't like this don't track your fuel mileage with the trailer on .

emissions choked diesels are not what the previous versions were .

I know a few guys that have had both styles and the new is nice but the choked down motors leave a bit off the table.
 
My 2014 2500HD LML pulls Penny like a beast. She doesn't slow down for much less than a 5% grade with 15k behind her. Mileage drops to around 11 or 12mpg towing at 75mph. Empty is closer to 19 - 20.
 
My 86 k5 on 1/2 ton axles and 36" swampers weighed in at 5700lbs. I bet you are barking on 7k with your setup.

My dad's 12 3500HD pulls my K5 on a heavy 14k trailer like a boss.
 
Yeah something sounds off... My dad helped bring home my donor Yukon XL with his new 2015 d-max Sierra and he had to keep slowing down all the way home because the truck kept creeping up past 80 mph before we realized how fast we were going (speed limit when towing is 55 mph in CA). I think those Yukon XL's weigh around 6000 and it had to be loaded ass end first so I'm sure the aerodynamics weren't helping but we couldn't even tell there was anything behind us until a crosswind kicked up...
 
Sounds like you are not sure on your weight. How do you know the trailer weighs 4K?

65mph on a decent hill with 10-12K? I'd call that acceptable. If you had a carbed 454 you'd be doing 35mph and getting 4mpg.
 
Sounds off. Kinda like me towing this year with a collapsed soft fuel line. Ran out of steam on the hills when she used to just pull up it. Your truck has more stock HP than mine does tuned. Those new trucks hardly need a programer at all.
 
Weigh the trailer and remember you have a double overdrive so it kicks down twice just to get to a 1:1 trans gear. Early allisons kicked down once to get to that gear. Kicking out of double overdrive on just about any hill wouldn't cause me any alarm, it's a coaster gear with a big trailer.

And remember at freeway speeds the aerodynamics of the trailer matter a LOT. And headwinds. Take 70mph road speed and a gentle 10mph headwind makes the truck think you're doing 80 which is a lot more load.

I find that my tuned up Dmax gives me the ability to burn a crap ton of fuel when I want to go fast up hills. I can get double digits towing or 7. On a cold day with 30+ lbs of boost you can guess which is closer....
 
thanks for all the input guys. I am still not 100% sure something isn't right with it. It may just be the torque management kicking in. Also i got the trailer weight off the internet. It was a 24 ft double axle flatbed trailer. 4k may be a little low, but not sure. Also i guess my blazer could be around 7k. not sure there either, so my trailer weight could've been closer to 12k.

I may wait until the warranty runs out and just go ahead and tune/delete it. that should fix all my problems.
 
Why is everyone trying to pull heavy at 75-80mph? I realize our speed limits are lower here in CA, but when I try to go that fast my fuel milage takes a DUMP!
 
My double axles 25' goose neck came in at 6000 lbs.
 
Definitely doesn't sound right.

We have a 2011 Sierra 2500HD LML and a 2014 Silverado 3500HD LML that both hall our flatbed & backhoe around without too much trouble. Steep hills at interstate speeds will cause it to slow a bit, but it can still maintain speed with traffic fairly well without too much effort. Truck, trailer, and backhoe gross in at 36k; 25k on the trailer and 11k on the truck.

20141022_162806.jpg
 
Your truck will never hold speed with that much weight in six gear. I have a 2007 with efilive on it. I pull a 30' travel trailer that is around 9000 lbs. I pull it in 5th gear because 6 is to high of a gear for that much weight. It will lug the motor more in 6th witch cause the egt's to be higher witch means it is burning more fuel and getting worse fuel mileage. Also if you push them to hard with to much boost you will strach the head bolt over time. I know because I did it. Now I have studs and it was not cheap to fix.
 
I have a '15 LTZ Crew with 4wd, I have pulled my car trailer with two jeeps in it with no issues through Adirondack Park. The thing flies. I would have yours checked, something sounds wacked. My '14 2500 Denali with a 6.0 couldn't get over a blade of grass with the same trailer. I should say it was that bad, but on the highway the 6.0 really struggled to the point I would even attempt the same trip.

20150517_085634.jpg
 
How many miles are on it? Getting past 10-15k seems to help these trucks break in a bit too
 
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