ousig2408

ok so something completely new with our Tahoe never felt it until maybe a day or 2 ago...now that I have noticed it I can feel it really anytime going above 40mph but holding steady speed going up a slight incline. we just took a 700 mile round trip this weekend so I noticed it A LOT. basically when crusing flat it is 100% smooth but when we start going up a very slight hill it starts vibrating (like the tires are out of balance) but they are not. The whole dang truck vibrates - enough to be real annoying

if I am using cruise and I increase the MPH 1 or drop it down 1 the vibration goes away until the truck settles into that speed and it starts again. same thing happens w/o cruise, if I give it a bit of gas or let off it goes away.

it is like when the torque converter is locked up ,maybe - it doesnt do it when accelerating quickly but only when just enough to hold speed and not downshif

so I think it is something to do with the engine mounts or maybe the driveshaft?

wondering if anyone else can chime in. I plan on taking it in next week when I am off work.

73shark

Did you notice if the vibration coincided with the V4 mode?

ousig2408

if anything it starts when it changes from V4 to V8 when going up a slight incline to hold speed. it will vibrate the whole time unless I adjust the speed up or down, then it will be smooth again once the road levels back out.
I have noticed it a few times even driving around town so I am thinking something is out of balance for sure - what exactly I dont know yet. But considering it doesnt do it all the time (only in specific situations I listed) I would have to rule out the tires right?

I will try to take it in this Wednesday when Im off work.

in2pro

Upon acceleration would tend to lead me to thinking a misfire but that should be showing up with a code unless its not that bad yet...

ousig2408

it is not just when accelerating - it is only when holding speed going up a slight hill. so imagine just a bit more stress on the drivetrain. accelerating normally is 100% fine or even up a hill is fine. so that is why I am thinking maybe engine mounts or driveshaft
no codes and gas mileage is still very good (well for this thing on the highway). we got nearly 21mpg for the whole trip

in2pro

You could rotate the tires just to see if any thing changes...
check and make sure nothing is wrapped around the drive shaft and give the U-joints a check for anything obvious is a good place to start before taking it in...

ousig2408

yes I may try that 1st. it was enough for my wife to notice so I know it was legit! there are a few other things I was going to have them fix also. noticed the power lumbar in the passanger seat doesnt work anymore and some other minor things. either way I will update the thread once it is fixed/figured out

ousig2408

dealership couldnt get it to do the same thing (of course), but they said they were overbooked and understaffed so asked if I could come in mid Jan so they could really look at better. I used the same service guy as I always have and he also thinks it is a torque converter issue and plans on replacing it all when I come back. He also said he heard some valve ticking. I have not really noticed. But he said he heard it 2 times and will look at that also when I come back in. So it could be a combination or 1 or the other. I will follow up
BTW they did replace our power lumbar system in the passenger seat- $100 deductable since I got the extended warranty, would have cost nearly $400...

hicksvilleshick

the only thing that hasn't been mentioned that comes to my mind is driveshaft out of balance... I mean check motor and trans mounts, but if your sure it ain't the tires, and without any other symptoms thats where I'd look.


:chug:

ousig2408

the tires arent great by any means but considering is only happens when going under slight load I consider it has to be a drivetrain issue. I agree I told them to check the TQ converter or the driveshaft. but I will certainly update after I take it back in a few weeks