Vibration

[Douglas L Self]

I have a 2020 GMC Sierra 1500 5.3 with less than 11 K miles I have had it in for the problem 3 times. I am told there is nothing that can be done to correct it. Here is the problem,  at any speed (especially highway speeds) a vibration occurs frequently, it only last a few seconds but a mile or so down the road it will happen again. This happens on flat roads hilly roads and can really be felt on smooth roads. The last time I had it in the service department they said it is happening when the engine changes from 8 to 4 cylinders and back to 8 cylinders and that there is nothing that can be done to correct it. It is hard for me to believe that GM has built a vehicle with a very annoying problem and it can’t be corrected. I am thinking seriously about putting signs on the truck that says (DON'T BUY GMC TRUCKS THEY CAN'T FIX PROBLEMS WITH THEIR MOTORS). I paid way to much for this truck to have to have to go down the road with it vibrating and shaking, very annoying!! Suggestions anyone?

[Rodek]

My wife had a Honda Accord V6 with cylinder deactivation. Depending on engine load, the car would run on 6 cyl, 4 cyl or 3 cyl. There was in indicator on the dash that would light up (ECO) when the car was running on less that 6 cylinders. During that time, I could feel a slight vibration. When the car would go back to 6 cylinder mode (going uphill, passing, etc) the vibration disappeared.

 

I have a 5.3 with Dynamic Fuel Management (DFM) and the 10 speed transmission. Although the truck doesn't indicate when the engine is operating in less than 8 Cylinders, I can feel it when is is doing it just as I could in that Accord. If I roll into the throttle, the vibration disappears completely....Again, just as it did in the Accord.  

[EricTheRed]

You can disable the DFM with the Range device.

 

https://www.rangetechnology.com/products/afm-dfm_disabler/

[Boondock]

So I just bought an At4 with a 6.2l 10 speed trans. That does the same thing, I also have found that it does it all speeds but what seems to be the most relevant predictor of noise is a mpg range of about 30-40 mpg. I get this noise/vibration coming from the exhaust that sometimes gets bad enough to feel in the cab for a brief second. I have also found during the right circumstances it will do it in when the truck is in reverse while sitting still. I can take my foot and press against the exhaust and the noise will go away. I guess I'm going to take it back to the dealer with less than a 1000 miles on it seems like it definitely shouldn't do that.    

[childstoys]

18 hours ago, EricTheRed said:

You can disable the DFM with the Range device.

 

https://www.rangetechnology.com/products/afm-dfm_disabler/

It may take the $200 to prove if that is really the issue or not. Seems like the best way to debunk their claim though. Then I'm sure they would get you on the technicality that you altered the trucks computer. Tough one either way. 

[Boondock]

So today I went searching for my vibration/ noise knowing it was coming from the tail pipe I went looking for places the tailpipe might be vibrating against the truck and bingo the tail pipe was within a .25” of the spare tire heat shield I Jammed a wooden wedge between the two now 98% of my noise is gone. I’m not saying this is the fix but at least I don’t hear it anymore hoping somebody else can duplicate.