2020 2500Hd feels like it is surging when towing a hill

Another JR · October 17, 2021

From what I’ve read on this, there’s an extensive flushing procedure they are supposed to do per the service bulletin when they replace the TC to get all the contamination out. You might ask them to describe the flushing procedure they did. If they left contaminated fluid in, the second TC may shudder.

lurker_007 · October 17, 2021

I’m not sure how extensive the flushing procedure was. I do know that they flushed and filled the transmission after the work was done. Odd part is that the jerking happens at the same rpm range every time. Might be about to trade for a diesel

downsj · August 11, 2023

On 3/18/2021 at 10:53 AM, L8T said:

Same here but it does it in most all gears. Really noticeable in 2nd to 4th between 1450 and 1700 rpm.

No fix for it yet. Complain to your dealer and get it booked in otherwise gm will never look into it.

I have the same issue on my 2022 L8T. I noticed it in West Virginia with an empty truck. It feels like it’s dropping quite a bit of power and then returning it suddenly. It’s not a torque converter shudder, I’ve had that on a car before. I haven’t complained yet but I am planning to when I get the rest of my deleted options installed.(chip shortage)

GMCustomerService · August 31, 2023

On 8/11/2023 at 11:14 AM, downsj said:

I have the same issue on my 2022 L8T. I noticed it in West Virginia with an empty truck. It feels like it’s dropping quite a bit of power and then returning it suddenly. It’s not a torque converter shudder, I’ve had that on a car before. I haven’t complained yet but I am planning to when I get the rest of my deleted options installed.(chip shortage)

This is certainly not what we like to hear, downsj. Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2022 GMC Sierra. To do so, please send an email to [email protected] with ATTN: downsj/GM Trucks in the subject line.

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Another JR · September 1, 2023

I wonder what it is about the most recent post from downsj that triggers the bot to offer GM help when all the other posts were ignored.

downsj · November 30, 2023

On 10/6/2021 at 2:50 PM, lurker_007 said:

Sorry everyone. I know this is an older thread but I have been searching for weeks and came across this today which almost describes my situation perfectly. Looooong time reader (5 years or more) but I have never joined up until today.

But I was hoping for some insight from anyone on this post or familiar with this issue.

I have a 2021 2500HD 6.6 gas. I pull a fifth wheel of around 11,500 lbs. My issue is when I am accelerating while towing I start getting a jerking/misfire "fishbite" feel starting around 3000 rpm up to about 4000 rpm. This started at about 12,000 miles on the truck. It mainly happens in 3rd gear between 3200 rpm and 3800rpm but has started doing it in the end of 2nd gear and even 4th occasionally.

I brought the truck to the dealer with the trailer attached and the tech rode with me. He felt it as well. He brought along a laptop that was connected to my truck. He recorded some snap shots of all the data while it was doing it. The data was submitted to GM and they noted that the slip speed was more than tolerances allotted. They recommended replacing the torque converted and inspecting the trans pump. My pump had a few cracks so he replaced the pump rotor and torque converter. I was hoping for it to be over. However once I hooked to my trailer again, it was still there. Just as bad as before. We did another test drive and recorded the data again but he and another tech seem to be at a loss as to what is going on.

Just FYI it does it with or without tow/haul engaged, cruise on or off, air conditioning on or off, stabilitrac on or off... none of it matters. I have even pulled it without the trailer plugged into the electrical to eliminate any trailer brake malfunctions... It happens around the same RPM every single time. I have pulled 4 other trailers the heaviest of them weighing about 7000lbs all bumper pull. No issues present on any of them.

I am waiting to hear back from the dealership still but looking for answers on my own

Thanks!!

I have had this same issue since the truck was brand new. I first noticed it with an empty truck on a long mountain pull in West Virginia. It seemed engine control calibration related. After pulling some heavy trailers (also with surging) is seems a little better. I think GM spent absolutely no seat time in calibration with this power train and heavy loads. It never does it with an empty truck where I live which is 6 miles from the GM proving grounds.

Pryme · November 30, 2023

12 minutes ago, downsj said:

I have had this same issue since the truck was brand new. I first noticed it with an empty truck on a long mountain pull in West Virginia. It seemed engine control calibration related. After pulling some heavy trailers (also with surging) is seems a little better. I think GM spent absolutely no seat time in calibration with this power train and heavy loads. It never does it with an empty truck where I live which is 6 miles from the GM proving grounds.

Higher rpm’s while towing and in mountainous regions? Could this be detonation that the knock sensor is not controlling? Bad gas?