When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Went up north this weekend and my 2018 6.7L felt like it was shifting poorly while towing. Wondering if anyone else has experienced this or if I should take it in
It was smooth the entire time pulling my 7500 lb toy hauler except the elevation change of 4-6% grades. Going uphill it would struggle to find the right gear and often stayed in lower gears. This makes sense except that it was really close to redlining and stayed there despite me trying to pedal it to find a better gear. Though downhill it kept staying in 3rd gear and I couldn't get it to change gears there either. I get all this but the engine was really overworking at the time. Trany temp was 224F. Tow/Haul on/off didn't seem to have any affect. I wasn't in manual shift mode but it wasn't a good place to pull over anyway.
My guess is something to do with the PRS (Progressive Range Selection). Any ideas?
I've had that happen a few times as well. Uphill it downshifts too late and then jumps two gears.
After going downhill it stays in a lower gear for longer than I think it should. As you said, the rpm's
are too high already to try to get it to upshift by accelerating.
Usually, for me, turning off Tow/Haul until it upshifts works.
I also manually downshift going up hill using the +/- button on the shift lever.
I think it also senses the angle at which the truck is. I've noticed mine will hold a gear even when not towing going up an incline. Even if I lighten up on the peddle it will still hold until the truck levels out. It knows more about where it is than we do sometimes.
Sounds pretty similar. You ever have the dealer look at it?
Originally Posted by klbrown
I've had that happen a few times as well. Uphill it downshifts too late and then jumps two gears.
After going downhill it stays in a lower gear for longer than I think it should. As you said, the rpm's
are too high already to try to get it to upshift by accelerating.
Usually, for me, turning off Tow/Haul until it upshifts works.
I also manually downshift going up hill using the +/- button on the shift lever.
Staying in too low a gear for too long on a downhill run while towing is not uncommon around here. I don't have any shifting issues going up hill. I point it uphill and it does it's thing very well.
You don't have to pull over to shift to manual mode.
^^^^^^^^ here ya go. Put gear selector in “M”, use the +/- button on the gear selector to choose which gear you want, just like a manual, but without the clutch.
I think it also senses the angle at which the truck is. I've noticed mine will hold a gear even when not towing going up an incline. Even if I lighten up on the peddle it will still hold until the truck levels out. It knows more about where it is than we do sometimes.
I agree! I think the inclinometer (sp?) is involved in whether the truck decides to upshift. I think it delays upshifting if it senses climbing is going on.
I'm wondering about why, not how to manual shift. It all made a little sense but concerning it would get so close to redlining but never shift, if even for the sake self-preservation. The motor sounded really strained, more so then just high RPMs, which is why I considered pulling over. With torque peaking at 1800 RPM and HP at 2800, a sustained 3800-3900 was too much
Sounds pretty similar. You ever have the dealer look at it?
No. It happens so seldom. For me it usually happens when towing and in cruise control. Cruise
control always seems to be slow to adjust to speed and terrain. Up hill it downshifts 2 gears where
if I manually downshift one gear I can pull the grade.
Down hill I set the cruise to at least 5mph slower than I want to go and it will hold the speed I actually want.
I had this issue going down hill so I shiftedinto manual and hit the plus button to bring the RPMs down. At that moment I had the engine brake on. Others have suggested using the EB in auto mode instead but I havent had a chance to test this.
Sounds like you were running up and down elevations and working it. Try slowing down and manually shifting it. You can carry a little more speed without straining it if you know what you are doing and take over sometimes; its not like a computer can see a hill or notice grade changing gradually.
If its getting hot with 7500lbs then you are really letting it search gears. Is that the actual weight or dry? Lots of headwind?