Vibration or grinding noise

JEFF LYMAN

MEMBER
2014 GMC SIERRA
6.2L
V8
4WD
AUTOMATIC
110,000 MILES

There is a vibration or grinding noise at times. It almost sounds like you are driving over rumble strips even though you are not. This is on the trucks that GM had that go into V-4 mode to improve gas mileage. This noise often comes at the top end of V-4 right before going back to V-8 mode although this is not always the case. The noise/vibration does not ever happen when accelorating aggressively. The noise/vibration only comes in relatively short bursts of a few second. At times it is quite loud and I think I can feel the truck slow a little like the brakes have been applied.

Friday, March 13th, 2020 AT 5:53 PM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Okay. Try something for me. When you get the vibration happening in all cases, push the tow/haul button and see if it goes away.

I think you are on the right path with it being in 4 cylinder mode. Most OEMs that offer this, struggle with this issue. Basically in 4 cylinder mode there is not enough power for the situation you are in and it makes what is called a drone. This can cause a vibration as well.

Ram trucks had this and they actually released software to put it in MDS "lite" mode. This means they don't bring it in a lower speeds or lower RPM to try and minimize this.

Let me know what happens when you do this and we can go from there.

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Friday, March 13th, 2020 AT 6:45 PM