Towing with 6.6 Gas 2022 GMC 2500 AT4

GovernmentMotorsFan · May 31, 2022

I purchased a GMC 2500 AT4 last week with this gas 6.6. First off I really do like the truck. I like the AT4 package and all the features. Overall it seems like a well built truck and I don’t have any complaints. I started to tow pretty quick with the truck after a couple hundred miles. The last items I hauled was 6,200 pounds. I think the truck performs better not in tow haul mode. In tow haul mode the truck is in a lower gear, only wants to shifts at 3k rpm’s and will down shift while slowing down and kick the rpm’s up to 3.5k. When I came back home I didn’t put the truck in tow haul mode and I feel like it did 10 times better. Wanted to see if anyone else has hauled with the 6.6 gas and had the same thoughts. Maybe you need to get in heavier items for the tow haul to be effective.

sheath · May 31, 2022

No experience with light loads, but others have, and can speak better to your points.

FWIW:

I've only towed heavy (14,300 lbs & 14,600 lbs) with a large frontal area (wide body 5th wheel travel trailer). Tow-Haul mode works better for me at that weight. Especially in the mountains. Torque converter locks up earlier to control transmission temps.

The transmission programming in L mode could be better. under heavy load it wants to drop down to L2 at over 5K rpms, even under partial throttle. So I end up just slowing down, to keep it between 3,500 rpm-4,200 rpm. It can still out pull a loaded big rig up a 6% plus grade (not meant as a brag, it just does). I pass them going up, they pass me going down. Rinse & repeat... lol

On the flat steady state cruising I can't tell any difference.

Fuel mileage in tow-haul mode has been pretty reasonable. 7.5 mpg to 8.5 mpg. That is only a couple of miles per gallon off a stock '07 Dodge Ram with the 5.9L Cummins. However, the Dodge did a much better job of maintaining freeway speeds through the mountains, both up and down.

Happy Trails! :cheers:

WondersAwait · May 31, 2022

I tow a moderate sized trailer for work via bumper pull, and it's about 6,000lbs empty and can be 10,000+ lbs loaded. I never use tow-haul mode for the trailer empty and usually only use it when I have the trailer pretty well loaded up roughly 9k+. I don't like how it shifts with light loads at all and non-towhaul works just fine. I love how it adjusts to heavier loads though and it's excellent for the increased weight.

When towing our 11,000lb fifth wheel via gooseneck conversion, always tow-haul mode and it pulls like a dream.

nocturnalmotors · May 31, 2022

If I recall, the manual states not to use tow / haul unless >75% capacity.

GovernmentMotorsFan · June 1, 2022

9 hours ago, WondersAwait said:

I tow a moderate sized trailer for work via bumper pull, and it's about 6,000lbs empty and can be 10,000+ lbs loaded. I never use tow-haul mode for the trailer empty and usually only use it when I have the trailer pretty well loaded up roughly 9k+. I don't like how it shifts with light loads at all and non-towhaul works just fine. I love how it adjusts to heavier loads though and it's excellent for the increased weight.

When towing our 11,000lb fifth wheel via gooseneck conversion, always tow-haul mode and it pulls like a dream.

12 hours ago, sheath said:

No experience with light loads, but others have, and can speak better to your points.

FWIW:

I've only towed heavy (14,300 lbs & 14,600 lbs) with a large frontal area (wide body 5th wheel travel trailer). Tow-Haul mode works better for me at that weight. Especially in the mountains. Torque converter locks up earlier to control transmission temps.

The transmission programming in L mode could be better. under heavy load it wants to drop down to L2 at over 5K rpms, even under partial throttle. So I end up just slowing down, to keep it between 3,500 rpm-4,200 rpm. It can still out pull a loaded big rig up a 6% plus grade (not meant as a brag, it just does). I pass them going up, they pass me going down. Rinse & repeat... lol

On the flat steady state cruising I can't tell any difference.

Fuel mileage in tow-haul mode has been pretty reasonable. 7.5 mpg to 8.5 mpg. That is only a couple of miles per gallon off a stock '07 Dodge Ram with the 5.9L Cummins. However, the Dodge did a much better job of maintaining freeway speeds through the mountains, both up and down.

Happy Trails!