tranny issue, need some help figuring it out

[Tig]

Its for an 07 Tahoe PPV
Here's my problem.
When accelerating it drives fine and shifts fine.
It's when I'm at cruising speeds, doesn't matter how fast or slow. If I stay at any speed for even the shortest period of time, it starts to shudder/shake. I feel it in the pedal and the steering wheel.

What are your thoughts on this?

Any info would be appreciated
Thanks

[GMCwantsLS1]

It might be the torque converter. Press on the brake lightly while still pressing the gas when it does it. If it drops out of lockup and the shutter goes away that might be the problem.

[Tig]

So, basically do a brake stand, hah?

[Tig]

I realize what you're saying now. I did that with the mechanic and nothing happened, rpms stayed where they were.
I went ahead and replaced the converter with an FTI , added a bigger cooler, had them install a shift kit jr and they tuned it to.

Picked it up the next morning, low and behold, it still does it but, now it does it at lower speeds. At lower speeds it shakes and sounds like metal is rattling.
I took it out twice and noticed it has not been resolved.
Basically its been sitting in my driveway all week because everyone is away.

What concerns me is, they supposedly hooked it up to HPTuners and found nothing out of the ordinary. He told me they had it hooked up while driving to. Still nothing.
Another concern is others have mentioned it could be a misfire.
I bought new plugs and am going to check another store for wires today.
If its a mis, I'm going to be pissed.

[farmtruc]

If it's mechanical and inside the transmission then they won't see anything using hptuners, no scanner or tuner can fix a mechanical issue with tuning.

Usually a misfire will be detected and the pcm will set a ses light; unless the pcm was tuned before and for some odd reason the misfire count was disabled.

be sure the misfire counts are set to stock as well as the dtc's; drive it with the scanner recording and take note of any misfires.

[Tig]

The shop I brought it to hooked it up inside the shop with my truck off and basically said "if it doesn't have any codes, I cant see anything".
It has not thrown any codes.
Can you set those counts back to stock using HPTuners?
I think my biggest hurdle is finding someone capable of using a scanner.

I wish I knew more about this stuff.
Thanks farmtruc

[farmtruc]

hptuners allows you to compare two files, so find an OS that matches and compare misfire counts.

they should be able to determine if the engine is misfiring during tcc lockup in 4th by reading the scanner.

[Tig]

Excuse my ignorance but, what does OS stand for?

I'll have to sit back and wait until Monday, unfortunately they have been away for the holidays and will not be back until then.
I have saved all the info that I have gathered from the forums, I'll be bringing it with me when I go see them.

Otherwise, I'll be making an appointment with a tranny shop recommended by a friend.

Thanks again man, I appreciate the help/info

[kewljay223]

Operating System. kinda like windows, mac, linux.... but for pcm's

http://www.hptuners.com/help/vcm_edi...ters_gm_os.htm

[fasttest]

What shift is it doing it at 1-2, 2-3?