Hi all...hoping maybe someone has an idea or experience with an odd shift thing w/ my 07 H3X. Drives fine, accelerates from stop fine, generally no issue...but if I slow to 10mph and go back to the accelerator it does a lag/hard shift kinda thing. Not a slip exactly, and not if I slow to 5mph or 15mph...just 10 +/- maybe 1mph. It is very annoying in parking lot travels or stop/go traffic!

It seems like maybe its not downshifting properly? And if this is what it is, can it be programmed to fix or is it mechanical?

I haven't had my Hummer too long/only driven it a few K and don't know all the idiosyncrasies yet but I know this isn't right and I don't want to do any damage. For now I just make sure I slow it further before getting back on the gas but would really prefer to get it straightened out.

75K, very well maintained, Tranny flush/fill didn't change it.

Any insight would be much appreciated...

 

when i get back on the gas at idle speeds it feels like slipping jumps by 500rpms then gain momentum immediatly

my car is 2009 has 43k miles i guess tranny fluid is original(which shouldn't matter) car was probably driven easy on its previous years of life

 

try to clean throttle body many have said it improved shifting(strange but it seems true)

i will do TB cleaning soon

 

Clean TB? Certainly cant hurt but I cant figure for the life of me how that would effect shifting...esp with my weird issue

And this is VERY speed specific...only happens re-accelerating after slowing to 10mph, maybe +/- 1mph...fine at 7or8 and under, fine at 11or12 and up...I think it just HAS to be something with the computer / a downshift point or something of that nature?

 

i've no idea either but i read somewhere it smoothed shifts

here's my issue
not really knowing speed exactly but when i get on the gas at speed bump rpm increase but without gaining momentum just reving then suddenly(but not jerky) it gains speed and rpm settles back
i guess its how the car was designed probably due to AWD and some play in components

certainly won't hurt to clean it up i didn't do that but very soon will do it

also try to disconect the battert it seems to lessen a clunk that i had when shifting to Drive
is our transmissions adaptive to driving styles?

Good luck

 

these sound like denial of tranny trouble!
anything that doesnt feel right in a hummer is just like other cars, there is something wrong

 

my full quote was: "...all the idiosyncrasies yet but I know this isn't right and I don't want to do any damage"

hardly denial...that's why I was asking for input from someone that might have had this happen/know what this is since the stealership said NPF and that wasn't good enough for me.

Though I do agree chalking slippage off to anything is...

 

capture video it may help, i am certainly not an expert

are you sure it's not slippage,? some cars really disengage clutches when coasting thereforethere isn't engine braking "honda does this sort of" i test drove one i think its 91 or so at 80kph and 3k rpm as soon as throttle released it goes to to idle rpm ~1000

i have what does lool like slippage at slower speed when accelerating after speed bumps
rpm goes to idle then when giving gas rpm increase and it starts accelerating ~ 500 rpm gap ""but its not jerky at all'"

we own 2005 lexus rx330 and it does the same thing too it's an AWD

sorry for long post hope that i've helped some

good luck

 

My 2010 Alpha/Offroad has done the same thing since day 1 brand new. I have had it checked and of course the dealer could not find anything wrong. After going slowly going over a speed bump, I wait a second before I accelerate and it doesn't do it. Mine is not jerky, you just feel all the driveline slack catching up.

 

Drivetrain slop. Normal for all 4x4 vehicles using a Transfer Case, every GM 4x4 I have ever owned does/did it.