RPMs fluctuating when accelerating under light load???

[CAtaylor]

Thank for all the help all. It is nice to know others see this too and it is just the tranny doing its thing.

 

I talked to the dealer and they said with the 6 speed and the Shift/Torque management system, the tranny will lock up and release at times depending on load to be in the best possible gear for fuel economy. It is normal.

 

I also noticed in M5, keeping the truck out of 6th until higher speeds are obtained, this issue goes completely away and the tranny stops fishing around for gears.

 

Lastly, I noticed the truck seems to have calmed down. I was told it may need to learn driving habits....even when it is in 6th gear at low speeds, it does it little if any, like it learned to hold the gear, or downshift. All I know is this baby is running great and I love it so far. Hope the next 200,000miles are this good.

 

Thanks again!

Yep if it continues contact black bear, Justin can make it go away. That exact issue is the main reason I had my 13 tuned. It will get a little better over time but the torque converter strategy will never learn enough to make it completely go away. It won't cause any issues other than worrying the he'll out of you so no worries there. I tuned my 14 right off of the bat so I didn't experience it with this one.

[IdeElectric]

How many miles did you have on your truck when you noticed it fading away?

 

I'm having the same issues with my truck. 2015 3500 with less than 500 miles..

[Gabe63]

Pulling up the hill to my house in 2nd gear at 1200 rpm my engine speed fluctuates from 11-1300 rpm. Sometimes I just hit the tow button when I am going to go up my hill. The trans shifts down and it seems to lug the engine. I assume the TC is slipping.

[scott19677]

Mine did that to before a tune. I had my TCM tune based close to the tow haul mode with higher pressure and shift points. Now when I am driving very slowly thru a parking lot or something

you can "goose" the throttle a little and it acts like I have a pretty loose stall converter and revs up but stays in first gear. Runs and feels a lot better. I only notice it now when I am coasting down on an exit ramp or hill. There is also a little shudder felt when coasting down. I have not yet been able to figure out why.

[Travgross]

I have the exact same problem with my 2015 Sierra All Terrain, along with a nice rear end vibration to go with it. Bought the truck Brand new on Nov 20, 2015. It now has 700 miles and sits at the dealership as I write this waiting on a transmission specialist. You might want to look a little further into that problem. I have a 2015 Silverado loaner truck with same drivetrain that will smoke the tires. Mine couldn't get out of its own way! Kind of pissed!

[f8l vnm]

My 2014 did this a lot. 6.2 with 6 speed. I think it's 99% tune

[Travgross]

So, I was told they put on 4 new tires for the vibration in the rear end. As for the gutless,shuddering,surging. And just nut less acceleration, they say premature torque converter failure!! What do you think GMC Fans???

[Travgross]

Come on?? Nothing?? To die hard for negative remarks?? Really??

[Travgross]

My loaner truck. Traction off, sideways on hard acceleration. My truck had better do that when I leave that service department. If not, quick u turn to your favorite place!!

.

[Christopher Shawn Sisk]

Travgross.. You get your truck fixed? What was it? I just bought a brand new 2015 mine doing same thing. Took it back to dealer this am

[Travgross]

The 4 new tires took care of the vibration. The torque converter and forward pump replacement helped but not completely. I took it back a day later and took another test ride with the shop Forman. He knew I wasn't happy and a little concerned. He suggested that I just drive it, finish breaking it in and we will reevaluate at my fist service at 5000 miles. I gotta say it is running better. I use the M5 to keep it from constantly going into v4 mode around town, that helps! I still have a little shudder in my 1200 to 1500 rpm range with light acceleration and a harder than normal downshift at times. I'm at 2000 miles now. I'll keep you posted! Good luck!

[milligan]

I only notice it when towing and not using tow/haul mode. Does it going down the interstate. Doesn't bother me, but if I had an exhaust I bet it would get annoying.

[Reegs]

Have you ever found out what was causing this? I don't think this is normal my 2013 does it real bad at 30-40 I have it narrowed down to at least engine. I was thinking of a injector issue or thottle body. I have a Diablo tuner and I checked injectors and they all failed the ground test. I'm thinking when under load its jumping around. But I have no idea how to go about checking. I don't want to stArt throwing parts at it

[redwngr]

I didn't read the entire thread, but rpm on mine will fluctuate under 'light' load when it switches between V8 and V4

[Blarny4u]

My 2010 just started doing the rpm flux under light load. 170k. Till now, very smooth. Anybody find a fix? Driving around in M5 isn’t a fix to me.