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Transmission "Bump"

C

CharlieC

Full Member
Joined
Nov 8, 2006
Messages
27
Location
Flower Mound, TX
I've got an 8 month old 5.3 LTZ Avy and have noticed an occasional/noticeable "bump" from the transmission it feels like, about 10 seconds after coming to a stop. Not every time, but more than once in a while. Almost feels like a down-shift of sorts, but it comes after I've been sitting still for a bit. Any guesses?

Thanks,
Charlie
 
Hi,

    Sorry to bring up an old thread, but I seem to have this same "Bump" feeling on my 07 Z71.  I would describe it exactly as Charlie does, which I think is very different from the thread that Wildfire pointed to.  This bump or slight surge happens when fully stopped and waiting at a light for instance.  You could be waiting at the light for 10 to 90 sec and you will suddenly feel a very slight bump, I almost thought someone got too close and bumped me from behind the first time I felt it happen.  I had not noticed if the rpms jump at the same time, but suspect that they must.  I have noticed it only when the engine is still rather "cold" and tranny reading under 100F.  I almost always notice it within the first few stop lights when leaving my house first thing in the AM.

    Anyone else feeling this?  Just a little bothersome...I keep checking the rearview for the guy who just touched my bumper...

Thanks,
 
Yes...did not notice it this summer but since it has been cooling off it has resurfaced. It is seems to happen before the Av gets fully warmed up.
 
Thanks Steve,  is the update for the "bump" while stopped issue I'm having, or the surging while foot is off the gas and slowing that Wildfire pointed to in the other thread?

I'm asking only because I only experience the bump and not the other problem mentioned.

I have to bring it in for a leaking exhaust at the flange between the CAT down pipe and the rest of the exhaust any way.  I might as well have them dig into this as well.  Though minor, it is annoying.

Thanks!


 
I really dont know ... someone once posted a GM site that has all the updates available that I refer to ... unfortunately, the site gives generic descriptions, no release dates, and cryptic version info....

No wonder the techs get it wrong so much!  You need a phd to decipher whats applicable to what...
 
steve841 said:
There is a software update to fix this issue ...

Visit your dealer ...
Click to expand...

Actually the E-85 ECM update caused this condition, also gave it a partial surge but it is barley decernable now...more likely is that I got used to it.


WYDAH said:
Thanks Steve,  is the update for the "bump" while stopped issue I'm having, or the surging while foot is off the gas and slowing that Wildfire pointed to in the other thread?

I'm asking only because I only experience the bump and not the other problem mentioned.

I have to bring it in for a leaking exhaust at the flange between the CAT down pipe and the rest of the exhaust any way.  I might as well have them dig into this as well.  Though minor, it is annoying.

Thanks!
Click to expand...

You are probably going to find that the exhaust deal in is NOT a leak but a drainage area to push out the moisture from the exhaust...at least that is what the dealer said on mine.
 
Call me crazy ...

Calibration to address customer complaint of transfer case launch bump. Not for use in vehicles that do not exhibit this condition. Must be used with data file 24239929. Record use of this data file in GMVIS repair comments. See PIP3702.
 
I'm turning in to a post whore on this today I guess, but I lost 2nd and OD gears today, so this "Bump" sure wasn't an anomoly.  2WD  26K miles.  I'll find out if it's a replace or rebuild in a couple days.

Charlie
 
That's not good to hear.  I've only got 2700 miles on mine and I've felt this since day one.  I'd like to think my problem is related to what Steve posted about the E-85 update causing this condition, though I'm not sure if my truck had this E85 update performed.  I did have my truck in for service last week for an exhaust leak and asked about any BCM updates and they said the only update was for the battery run down fix #07033.  All the other tranny shifts on mine seem fine....

Let us know how you make out with your's.

 
My tranny went out at about 15K miles.  It was the sprag gear and all I got was a rebuild.  The tranny still does the initial bump on engine startup and at stop lights.
 
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