Just returned from a trip into the Ozarks last week and noticed that while on the highway when Active Fuel Management shifts into V4 mode I have a slight vibration that can be both felt and heard. At first I thought it might be a tire but noticed that it only does it when in V4 mode and seems to get more prominent the longer it is in V4 mode. Once it shifts back to V8 mode both the noise and vibration go away. The best way to describe the vibration would be along the same lines as how it feels when you drive over the lane edge indicators along the interstate. Obviously, not nearly as rough but at the same frequency if that makes sense.

Wondering if anyone else has noticed the same.

 

Do you have an aftermarket exhaust????

This "drone" is very common for the guys who put aftermarket exhausts on....including me

Search "drone"

 

first thing I think of is a possible miss-fire, as this would be more noticable in V4 mode, but I would think a code would set. I'd check and make sure all the plug wires are fulled seated.

 

AZSCTACO:

Good idea but this Tahoe is completely stock.

in2pro:

It's not caused a Check Engine light but I'll check to see if any codes are stored as well as checking the plug wires as you suggested and will report back. Thanks.

 

No codes stored & plug wires tight. Any other ideas?

Thanks.

 

I haven't seen one yet that didn't do it. Unless yours is really worse than the others. I can always tell when it's in V4 mode without looking at the dash. There isa little more vibration and the engine takes on a little "roughness". Pure B.S. that there is no telling when it changes. I'm guessing it's normal, see if you can drive another truck.

 

Mine sounds similar to a Jake brake, only muffled if that' any help. And I didn't notice any change when I put on the cat-back exhaust.

 

Until the return trip the other day I could never tell when it was in V4 vs V8 and was quite impressed as I was always sceptical before buying it that I would be able to tell. Maybe my old ears cleared out in the mountain air and now I'm back on flat ground I'll stop noticing it. lol Anyway, thanks for everyone's input. At least I now know I'm not the only one out there.

 

just press harder on the gas

is it under warrenty? stop by the dealer

as in Lake of the Ozarks? I hear that's a neat place, my dad was there a bit ago for the OSS races... his buddy owns Wild Ride (a race boat)

 

depending on how many miles you have on her it might be time for a bottle or 2 of injector cleaner or a few tank fulls of premium