Low RPM shake/ vibration?. stutter?

Boondock · September 13, 2020

Just Bought A 2020 AT4 6.2l 10 speed and at about 30mph I get a rumble sounds from what sounds like the rear of the truck?? Its just really hard to tell. A mechanic friend of mine also said he felt a shutter under really light acceleration. I have noticed a twitch in rpms while this sound is happening almost like it is caught between gears/dfm settings or the rpms are just dropping to low. The truck seems to run fine otherwise but I don't know seems like it shouldn't happen at all with less than 600 miles on the truck.

aliveguy5 · September 24, 2020

I have a funny feeling that this may be a symptom of cylinder deactivation and the torque converter adjusting to it.

dwchapmanjr · September 27, 2020

Shudder under light acceleration at 1100-1300RPM sounds like the TCC shudder issue on the 2015-2017's (I've had it for a few years before the new fluid finally fixed it).

Has anyone had the dealer run a picoscope on it to find the source?

Boondock · September 28, 2020

I think it is cylinder deactivation. If I put the truck in L9 which is my only option since ranger doesn't have anything available for 6.2 10 speed the truck seems to completely heal itself of any vibration/low rpm issues(gas mileage doesn't look as good) . I also found that most of the noise is coming from the exhaust pipe vibrating against the heat shield of the Spare tire so I wedged a block between the two. I know this only curing the symptom not the cause but the symptom is a lot less aggravating now. I dont know if L9 deactivates dfm or just overdrive but whatever it does its worth a try if you cant bare the little rumble strip feeling anymore.

JansterZ71 · January 6, 2021

On 6/9/2020 at 1:31 PM, Dersch said:

2020 LT Trail Boss 5.3L with the 10 speed crew cab 4x4

So trucks got about 1300 miles on it now. Im starting to notice a low rpm rumble/ vibration/ stutter? So i noticed it especially from a stop light. 1st and 2nd gear when im at really low rpms (think gently accelerating off the line). I can feel it in the steering wheel and in the seat. Like the only way i can describe it is it feels like im diving over tiny bumps. I wish i could describe this better but my buddy noticed it too this weekend. I also have the same exact feeling on the highway at low rpm when cruising. With this one i can almost reproduce it. If i speed up and slow down to a point where its ready to down shift but i give it slight gas i feel the vibration/ shutter/ rumble and definitely felt it in steering wheel. I know this is probably worlds worst description but best i can do. but once it happens you cant ignore it. The first time it did it i felt like the truck was stuttering to go but it wasnt.

I thought maybe this was a characteristic of the 10 speed with a big motor but not sure.

The obvious would be tires. they are new AT, balanced, and properly inflated.

Gonna take it in to get looked at next week maybe after my trip. But i wanna know if anyone else had this happen.

Any update on this? I have 17,000 miles on my 202 AT4 5.3L 10 speed and am experiencing the exact same thing. Your description was 100% spot on. I drive with a heavy foot just to not deal with it.

SSsierra · January 9, 2021

On 9/27/2020 at 8:41 AM, dwchapmanjr said:

Shudder under light acceleration at 1100-1300RPM sounds like the TCC shudder issue on the 2015-2017's (I've had it for a few years before the new fluid finally fixed it).

Has anyone had the dealer run a picoscope on it to find the source?

I have a 2020 sierra crew cab with 5.3, 10 spd trans and having low speed vibration 28-10 mph (deceleration or acceleration). I took vehicle to dealership on Monday. Two days later dealership called and stated all the test they performed (DFM, Trans mount ect..) was working as design and nothing could be found to cause issue. During this call I stated to service manager what was I suppose to do just live with this issue. I also stated that i was on GM truck forums and there where numerous identical issues, do I need to have a GM-Tech reach out to them? Service manager said let me talk to shop foreman/supervisor and see if there is anything he can do. Next day service manager was having another Pico scope test done to try and find issue. UPDATE; Shop foreman/supervisor called GM-Tech and they requested another Pico Scope be performed and to send them the results. Currently waiting on GM-Tech for guidance from Pico Scope results, should hear back from GM next week. I requested a loaner vehicle and dealership stated i could come get my truck and that it was safe to drive until they get the guidance from GM next week. Will update when GM gives guidance.

dwchapmanjr · January 9, 2021

19 minutes ago, SSsierra said:

I have a 2020 sierra crew cab with 5.3, 10 spd trans and having low speed vibration 28-10 mph

You may want to start a new thread. This one is specific to the 8 speed which has a few lawsuits against it and your issue may get mixed up in that. Frustrating to hear you're having to deal with it. I had to deal with it for 2-3 years on my 8 speed before the new fluid finally fixed it. I'm 2 years out on the new fluid and was hopeful the 10 spd was going to be better. Good thing you got a pico scope done on it. I have never been able to get that done for various vibrations.

SSsierra · January 10, 2021

22 hours ago, dwchapmanjr said:

You may want to start a new thread. This one is specific to the 8 speed which has a few lawsuits against it and your issue may get mixed up in that. Frustrating to hear you're having to deal with it. I had to deal with it for 2-3 years on my 8 speed before the new fluid finally fixed it. I'm 2 years out on the new fluid and was hopeful the 10 spd was going to be better. Good thing you got a pico scope done on it. I have never been able to get that done for various vibrations.

I am in the right thread, most on this thread are talking 2019-2020 issues with 5:3 and 6.2 with 10 spd

SilveradoTB217 · January 20, 2021

Update on my 2020 TB 5.3L w/ 10spd: As of today my truck is back at the dealer for a check engine light that came on. I still have a constant low speed shutter, but a new torque converter and transmission valve body have been installed on my truck. I'm starting to think it has something to do with the angle of the driveline or pinion shims on the Trailboss & AT4 models(because of the 2" lift on the trucks) I will keep you guys posted on what the check engine light ended up being. I've got 19k miles on my truck now and its starting to concern me that this issue can't be resolved.

On another note: If your a GY Duratrac hater like myself, this truck drives a lot better with Goodyear Ultraterrain AT's(exclusively sold at Discount Tire) I got my Goodyear to swap my duratracs out for them at 1200 miles after multiple failed attempts at high #'s on the road force with the Duratracs. If I end up keeping this truck, I will probably be going back to BFG Ko2's.

ajs800 · July 8, 2021

Anyone have anything further on this issue? My 2020 AT4 (5.3) has been doing the same for last 5k miles or so. It just turned 17k miles and my dealer did a fluid change with no change. Definitely feels like a torque converter issue or tranny slipping when lightly accelerating (light load). Truck vibrates, jumps, bucks, chugging feeling, etc. Does it in all gears,including L9, and is really noticeable at speeds 45mph - hwy speeds. Only way to avoid is it to stay heavy on pedal.

Liquid Plumber AT4 · July 8, 2021

On 6/16/2020 at 3:07 PM, Pappy58 said:

Just upgraded from my 2015 5.3/6 to a 2020 6.2/10. The 2015 had AFM and it was quite noticeable when in v4 mode and going from v4-v8, especilly when driving round at slow speeds, around town etc. I solved it by putting the shifter in M5 unless I was out on the highway doing 70+mph. So far on the 2020 I really cannot tell when DFM does it's thing. Any change is negligible. But this can also be solved by putting the shifter Ln and selecting a top gear range. In town where the top speed limit is 35mph, L7 is more than adequate. This also disables the start/stop crap.

I was just about to post about this same thing. Was it also causing a squealing/squeaking type sound when you were coming to a stop? Mine is doing this and i noticed today when i put it in manual and left it on and L setting number it never did it. I have a 2021 gmc 1500 AT4 6.2 litre. I have an appointment with the dealer and they mentioned faulty vakve springs/push rods??.....im no auto mechanic but if it doesn't make that sound in "L" manual mode then I wouldn't think its valve spring/push rods....correct.???? I wish I got one of the trucks without the DFM and AFM they are making now because of the chip shortage. I just want a true V8.....no going into V4 francis sally mode.

Other than the ranger LT module, is anyone making a true tuner or chip for these 2021 6.2 litre engines yet? Id love to disable the DFM and AFM, but still be able to put back to factory when its in for warranty service.

Thank you for any information.

ThatBossChevy21 · July 9, 2021

Ok guys I finally joined this group and let me start off by saying I just bought a 2021 Silverado trail boss with the 5.3L. Since day one I’ve had this weird skip/stutter feeling at low rpm’s. A little run down on my truck, I’ve installed a mbrp cat back exhaust, cold air inductions CAI, and the Pulsar LT module. This symptom I’ve been having does it no matter if DFM is active or inactive so I know it wasn’t that. So here’s my question tonight I just reversed leveled my truck and when I went to take off the factory nuts on the U bolts they were not tight at all. I’m talking like 30# tight. So I went on and installed the 1in block after taking out the 2in and installed the u bolts back and tighten them down to 85#’s. Just took the truck for a drive and what do you know no more problems! Now can anyone tell me how loose u bolts cause the low rpm skip/ misfire feeling!?

ThatBossChevy21 · July 9, 2021

22 hours ago, Liquid Plumber AT4 said:

I was just about to post about this same thing. Was it also causing a squealing/squeaking type sound when you were coming to a stop? Mine is doing this and i noticed today when i put it in manual and left it on and L setting number it never did it. I have a 2021 gmc 1500 AT4 6.2 litre. I have an appointment with the dealer and they mentioned faulty vakve springs/push rods??.....im no auto mechanic but if it doesn't make that sound in "L" manual mode then I wouldn't think its valve spring/push rods....correct.???? I wish I got one of the trucks without the DFM and AFM they are making now because of the chip shortage. I just want a true V8.....no going into V4 francis sally mode.

Other than the ranger LT module, is anyone making a true tuner or chip for these 2021 6.2 litre engines yet? Id love to disable the DFM and AFM, but still be able to put back to factory when its in for warranty service.

Thank you for any information.

Bad thing is yes they have a chip shortage but they are still putting all the components into the engine as if it has DFM just without the chip to control all of it. I’m running the pulsar lt and haven’t had any issues with the 2019 5.3 or the 2021 5.3(yet)

Liquid Plumber AT4 · July 10, 2021

4 hours ago, ThatBossChevy21 said:

Bad thing is yes they have a chip shortage but they are still putting all the components into the engine as if it has DFM just without the chip to control all of it. I’m running the pulsar lt and haven’t had any issues with the 2019 5.3 or the 2021 5.3(yet)

Thank you, I just ordered the pulsar lt and will get it set up and disable all the nonsense stuff and have a true V8.

ThatBossChevy21 · July 10, 2021

49 minutes ago, Liquid Plumber AT4 said:

Thank you, I just ordered the pulsar lt and will get it set up and disable all the nonsense stuff and have a true V8.

Awesome it’s the only way to go! I also just installed an oil catch can would be really surprised at all the oil I’ve collected in just 800 miles!