My 2016 GMC 3500 Denali was totaled a couple weeks ago. I was forced to go out and buy a new truck. Decided to move to the Ford because of all the technology and power these tricks put out. Purchased a 2018 CCLB SRW Platinum. Love the truck, rides well, feels strong, looks good.

Yestersay I pulled my 15k Solitude 5th Wheel over the I-70 mountain range in Colorado and I was not very impressed. It seemed like the truck was hunting for gears, with no throttle left to get up these hills any faster then about 35-40 mph. I started using manual transmission control to keep it on a lower gear to get power but the truck just seemed to struggle. I know your can’t race up hills with this weight but I expected to be able to maintain 60 mph on a 4-6% grade. It also kept shifting into 4th gear while on flat road going 68 mph, again like it was struggling to keep up or find the right gear. It was somewhat windy so I’ll give that some latitude Honestly, My old GMC pulled up these hills doing 65 no problem. Is there anyway to get more throttle response out of this truck or possible change gears. Any thoughts. Other than this I reallly do enjoy the truck.

Thanks.

Mike.

 

 

Sounds like gas. Turbodiesel performs better at altitude than NA gas. What's your rear ratio? The GMC only comes with 4.10s so it will tow differently than the 6.2 w/ 3.73s. If you have 4.30s, you shouldn't be having this issue at least not to this degree, though you are right at the edge of the tow rating so I would expect it to struggle a bit. If you're on gas on 3.73s, you are over the tow rating. I am assuming these are not DRW since you didn't mention it.

 

 

 

A head wind or even a side wind can kill you. I'd take 'er out on a calm day before trading it in......

 

My 2017 6.7 pulls 6% at 70 MPH with a high profile fifth wheel and a GCW of 26k#. If your gear puts you in the 6.7's seeet-spot at 2500 - 2900 RPMs and you can't pull grades at highway speeds, something's amis. Some gear combinations are just poor for pulling mountains heavy. Is the truck broken in? What RPM are you running pulling at 65?

 

 

 

 

Agree with 2009KR. 70mph all day long.
The best throttle controller is your right foot. "Throttle controllers" don't give any more power to the truck, they just change the %throttle input fed to the computer - you do the exact same thing with your foot.
As far as gearing, 3.55 or 4.30, doesn't really matter for what you're seeing. Where 2009KR and I would pull with 430s in 6th, you'll pull with 3.55s in 5th and have similar RPMs. Don't think a gear change will solve any issues.
Don't be afraid to use your right foot. The 6.7 loves it all day and night. Get those RPM up above 2200 ( or 2500-2900), and the truck should scoot.
Wind can certainly change a driver's day, but it you do find similar results in different conditions, something is wrong. I'd scan for any DTCs first and see if anything is set. If you have a monitor, watch it when pulling a grade to see if anything seems out of place. Maybe a fuel pressure drop, boost leak, oil temp high, etc.

EDIT - saw your response after typing mine. I'd pull for DTCs and monitor parameter performance. Seems like something is amiss. That response is not what the rest of us typically see (unless wind was just that bad)

 

You don't mention where your from, except you were driving over the Rockies in Colorado on a windy day. Just to let you know if the wind stops blowing in WY we'd all fall down. I've learned to watch which way the grass is blowing if I notice a performance drop.

 

Are you towing using the tow/haul mode? No problems pulling almost the same trailer up inclines with my truck..the 4.10's even at highway speeds provide great acceleration when passing or going up inclines.

 

 

There's part of the problem. I've written about this on a few threads. 2200 RPM, the top of the 925 ft-lb. torque peak range, is 2200*925/5252=387 HP. That's 88% of what you'd have with a better gear. 3rd has gobs of power, but can't hold highway speed. 4th drops well below the best 2500-2900 power region.

That's why the f450's 4.30 and F350 DRW's 4.10 are perfect for 65-70 MPH pulls, and the 3.55 is not. I don't have my gear spreadsheets in front of me, but I thought the SRW 3.55 with the 20" tire was a fine ratio, but with the shorter tire, it was not optimal.