Ill throw this out there just in case..
#PIP4168A: Low Power Poor Performance Or Busy Shifting - keywords 6.2 6L80 L80 L92 6sp accel accelerate apply APP clunk coast delay delayed down downshift engine fuel hesitate hesitation 180 late lazy MYC shift - (Aug 6, 2007)


Subject: Low Power, Poor Performance, or Busy Shifting
Models: 2007-2008 Cadillac Escalade2007-2008 GMC Sierra Denali, Yukon Denali2008 Hummer H2Equipped with the 6.2L Engine (RPO code L92) and a 6L80 Automatic Transmission (RPO code MYC) This PI was superseded to update models. Please discard PIP4168.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
<a id="d73965e33">Condition/Concern:Some customers may have a concern of low power, busy shifting, delayed transmission downshifts, or poor performance.
The customer may also explain they have to depress the throttle pedal farther than expected to get the acceleration desired.
These conditions may be caused by the use of regular grade fuel instead of the recommended premium grade fuel with a posted octane of 91 or higher. When regular grade fuel is used, the engine will produce less power, and the transmission shifting characteristics will change.
<a id="d73965e49">Recommendation/Instructions:When evaluating any of these driveability concerns it is important to determine if the vehicle is being operated on regular grade fuel. The owner's manual recommends the use premium unleaded gasoline with a posted octane rating of 91 or higher.
If the vehicle is being operated on regular grade fuel, request that the customer use at least two tanks of premium fuel with an octane rating of 91 or higher before returning for evaluation of the driveability concern.

 

This is what I was referring to on prev reply..
Models: 2015 and Prior GM Passenger Cars and Light Duty Trucks



This Bulletin has been revised to add the 2015 Model Year and remove the Important statement. Please discard Corporate Bulletin Number 99-04-20-002H.




Some customers of vehicles equipped with automatic transmissions may comment that the vehicle exhibits a clunk noise when shifting between Park and Drive, Park and Reverse, or Drive and Reverse. Similarly, customers of vehicles equipped with automatic or manual transmissions may comment that the vehicle exhibits a clunk noise while driving when the accelerator is quickly depressed and then released. Tipping into the throttle after deceleration can also result in some level of clunk as the driveline is loaded in one direction (coast) then with throttle reapply the driveline gets loaded in the opposite direction (drive). On manual transmission vehicles depressing the clutch while in a deceleration immediately releases load on the driveline and may produce a clunk noise as the driveline unloads.


Note: Compare this complaint vehicle to a like vehicle. If the results are the same, this is a normal condition. For additional diagnostic information, refer to the appropriate Service information.



Whenever there are two or more gears interacting with one another, there must be a certain amount of clearance between those gears in order for the gears to operate properly. This clearance or freeplay (also known as lash) can translate into a clunk noise whenever the gear is loaded and unloaded quickly, or whenever the direction of rotation is reversed. The more gears you have in a system, the more freeplay the total system will have.


The clunk noise that owners sometimes hear may be the result of a buildup of freeplay (lash) between the components in the driveline.


For example, the potential for a driveline clunk would be greater in a 4-wheel drive or all-wheel drive vehicle than a 2-wheel drive vehicle. This is because in addition to the freeplay from the rear axle gears, the universal joints, and the transmission (common to both vehicles), the 4-wheel drive transfer case gears (and their associated clearances) add additional freeplay to the driveline.


In service, dealers are discouraged from attempting to repair driveline clunk conditions for the following reasons:

• Comments of driveline clunk are almost never the result of one individual component with excessive lash, but rather the result of the added affect of freeplay (or lash) present in all of the driveline components. Because all of the components in the driveline have a certain amount of lash by design, changing driveline components may not result in a satisfactory lash reduction.
• While some owners may find the clunk noise objectionable, this will not adversely affect durability or performance.
• For additional diagnostic information, refer to the appropriate Service Information.

 

My experience is most noticeable w/ speed humps. There's a street that has these and I get through 1st and 2nd gear then hit the speed hump. I think what is happening is the tranny is thinking about going into 3rd b/c I let off of the gas to go over the hump. But on the other side of the hump I get on the gas again (not aggressively, heck we're on our way to church) and then I feel a really hard clang in the drivetrain. And I'm back in 2nd gear. If I put the tranny in M-mode and leave the truck in 2nd there is no freeplay.

Ultimately I hope this is the truth:

 

AND now I have the excuse I've been looking for to trade the'04 for an '08 I found that I really want! Sweet!!

 

Haha, your welcome

 

2006 h2 hummer I cant get the driveline to release from tranfer case can someone please help