Quote:
Originally Posted by Cliff R
"There's something wrong with that truck, or trailer, in my opinion. No way it should struggle that bad towing 1500 pounds."
There is absolutely NOTHING wrong with the 6.0 2500 GMC truck. Unless you missed it in my comments it was just fine on flat ground and ran really well once we came out of West Virginia into North Carolina and out of the steep grades and hard pulls on I-77 South.
We ran on down into Florida pretty much w/o any issues, it stayed in 6th gear.
On the return trip once we got into Northern Georgia the downshifting deal and revving to 5000rpms thing started all over again. The problem is with how GM set up the shift program in the ECM. They will NOT allow the engine to "lug" and the "manual" mode will not override the downshift program. So if you try to lock into 4th or 5th on a hard pull it will bypass those gears and go DIRECTLY to 3rd or even 2nd gear and sit at 5000rpm's till you crest the hill and remove the load.
What a total POS set-up. I'm sure the 6.0 will lug OK in the mid-range even with bigger trailers and steeper grades than we were pulling but the factory has them set up to downshift to lower gears and the engine just about ready to fly out from between the fenders instead........Cliff
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I know exactly what you're talking about Cliff. Dad bought his 2014 6.0 brand new and it's been that way since day one. It's just the way they are setup from the factory with those 6 speed transmissions. We've towed across country with it on multiple occasions. It's fine on flat ground but once you get out West here where the mountain grades are that transmission can't decide what gear it wants and most of the time it has the engine setting on 5,000 rpm to maintain speed. When we had to climb Bradshaw mountain from the Verde Valley coming into PV, it's a 7 mile stretch from sea level to about 7,000 feet. You basically have to keep the throttle matted on the floor, and the truck will maintain about 50 mph and 5,000 rpm in what I believe to be about 2nd gear. The truck just stays there for the entire 7 mile stretch. You can't let off the gas or you loose your momentum. It's a butt puckering experience constantly watching the temp gauge and the oil pressure, LOL Meanwhile people are blowing past you at 70 mph and you're trying to look as far ahead as you can for slower moving semis so you can switch lanes without loosing momentum. It's a real pain in the rump and really puts you in a dangerous situation. That's why I'm all about diesel these days, lol.