So ive got around 700 miles on my new lbz... Ive noticed on a few occasions now that when upshifting, it shifts into gear(2nd i believe, im never paying attn to shifts when it does it) and shortly (few secs) after it shifts it feels like i get a boost in power. Its not alot, but definitly can feel it driving. It stays at this new level as well, it doesnt umph up then back down, it stays constant. **edit- I should add when it does this, its smooth in the transition. Its not jerky or rough at all**
I dont have any reason to believe its slippage, as the engine tone (or rpm)never changes to indicate that im inbetween gears or something.
Another way i could describe it is, if you have ever driven on snow and say in a parking lot or on a rd you break the back end loose and fishtail a little, then when you hit drive pavement again you get that kinda quick jolt, it reminds somewhat of that...
Also, i might add that everytime i can recall it doing this, it it seems as tho its on a cold tranny right afterstartup. This morning i drove about a mile, turned and go another mile turn again and it did it. This afternoon left work drove 1.5-2miles went through a stop sign and did it...

Ideas???

Mine willnot lay all the power down till it is warm and ready to. You will notice the boost kick in more in second gear etc.. than first.... First is real short ..

Im familar w/the tranny with holding upshifts(just let the rpms climb)in order to warm up the engine and cab quicker in my 03. My 03 would hold 3rd gear for a while(especailly when it got good and cold) then 4th til the sump temp warmed up enough to shift into OD.
But this doesnt seem anything like that.

torque converter locking up is what it sounds like to me.

Sounds like it defueled on the 1/2 shift.

Boost coming on?I've driven a few new ones and they STILL seem to run stronger at part throttle.

did it tonight right after i pulled out of work, this time still in first gear just before it shifted to 2nd... Had 3-4mins warm up time, prolly 1/2 of it at high idle and outside temp of 5f. Truck had sat for about 8hrs...
Mike l- if it is that, is it somethign i should be concerned about?

Mine does the same thing. It has done it since new and with a programmer it's a lot more stronger. It feels like you have hit the nitrous button. It seems to start in 3rd gear for mine but keeps picking up speed until it gets scary. The one thing I noticed about my truck opposed to others, is my truck had a lot less out of the hole. Mine still does it with the Suncoast in it and a no defuel programmer. Only thing I can say is when they beat me out of the hole, they better be leaving me hard,cause when she hits third I'm going by em.

I stopped in and talked w/the service manager and a tech... They told me that Gm redesigned the warmup procedure and that it sounds like it could be this. They said it sounded even more like it, once i told them that ive only noticed it first thign when its cold
They told me not to worry about it, so..... I still would like to make sure thats what it is. Id like to see on ally website or something...