2021 Denali - Vehicle Knock, Stutters, Surges, Rough Acceleration - In Auto Mode, After Lifting Rods Replaced

[WalleyeMikeIII]

Thank you very much for the detailed response. Note: I have 2 speed transfer case, 2WD, 4WD, Auto, 4 Lo. You've given me some great talking point and they are much appreciated.

Its worth nothing a separate post was made 6 days ago with almost identical issues. https://www.tahoeyukonforum.com/threads/4wd-auto-problem.139109/

It is difficult to say whether that separate post's issues are the same as yours...one would need to drive both vehicles.
The advice you have received above is the best there is.
And, while my vehicle is quiet in Auto, it does indeed make slightly more noise in Auto than it does in 2HI.

I agree w/ all others that Auto all the time is probably not the best. But, clunks, bumps, excessive vibration is not normal, and any competent dealer should be able to debug and resolve.
Further, note, the transfer case only holds about 1 quart of fluid...so if you are constantly engaging the cluthes, etc, you are probably due for more frequent transfer case fluid changes than the manual specifies.

You are going to have to train the wife...this is not an AWD vehicle, it is a 4WD vehicle...and has to be driven as such.

 

[tom3]

This might sound like the the dumbest suggestion ever, but get a ruler and measure from the top of each wheel to the pavement. Adjust tire pressures to get all four to the same exact distance. Might take the tension off the AWD differential clutch in the Xfer case and smooth out the drive.

 

[Z15]

AUTO turns it into an ALL WHEEL DRIVE. Many All Wheel Drive Vehicle on the road so those that say to not use it are offering personal opinion not based on factual informatiion.

AUTOMATIC TRANSFER CASES
The last category is a combination of 4WD and On Demand AWD. These transfer cases have a 2HI, Auto-4WD, 4HI, 4LO and Neutral position and would fall in the general 4WD category. This transfer case has the operating characteristics of both an On Demand AWD and a Part-Time 4WD system depending on the mode selected. This transfer case uses a clutch pack to allow for a difference in speed between the front and rear axles in the Auto-4WD mode. In the 4HI or 4LO modes, there is no allowance for the difference in speed between the front and rear axles. An example of a vehicle with this would be a Sierra with a push-button transfer case with a 2HI, Auto-4WD, 4HI, 4LO, and Neutral positions.

 

[Z15]

This might sound like the the dumbest suggestion ever, but get a ruler and measure from the top of each wheel to the pavement. Adjust tire pressures to get all four to the same exact distance. Might take the tension off the AWD differential clutch in the Xfer case and smooth out the drive.

Bad Advice, all tires MUST be same air pressure or problem will arise.
GM Diagnostic Info

Driveline noises in 4WD or AWD vehicles caused by loading may be mistaken for transfer case or front axle noise because they can sound very similar. Four-wheel drive noises caused by loading may exhibit the following conditions:

• The noise will be greatest on a clear, dry road and decrease on a low traction surface. Front axle or transfer case noise caused by bearings, ring and pinion, or planetary gearing will be similar on all surfaces.

• The noises or feel that can be expected will increase while making a tight turn.

• The noises may be changed from a deceleration to an acceleration condition (or acceleration to deceleration) by raising or lowering tire pressure at one end of the vehicle.

TIRES
Tire rolling rates can be a major factor in operational characteristics. Consider the following important items:

• All tires are the same size and brand. Tires of different brands may have different circumferences (or radius) even if they are the same size.

• Tires are set to factory recommended pressures. A tire with low air pressure will roll at a different rate.

• All tires have approximately equal amounts of wear. Tires with different amounts of wear will roll at different rates.

• All tires are the same tread type. Don't mix on-off road, all-season or street tires on the same truck as they may have different circumferences and roll at different rates.

• One or more of the tires may show small, short scratches around the circumference of the tire tread. The tire "scuffing" on the road surface causes these scratches.

 

[jepaul2198]

Thank you all for your responses.

I'd like to make one thing clear here to everyone. I am NOT talking about ANY NOISE. From a noise standpoint I can tell a difference between any of the settings.

I am talking about feelings of stutter, surges, vibrations, rumbles, shakes, etc. They are small but absolutely are there and were not there previously. It almost feels like the truck is switching gears 5-7 times between each actual gear shift.

 

[adventurenali92]

It is difficult to say whether that separate post's issues are the same as yours...one would need to drive both vehicles.
The advice you have received above is the best there is.
And, while my vehicle is quiet in Auto, it does indeed make slightly more noise in Auto than it does in 2HI.

I agree w/ all others that Auto all the time is probably not the best. But, clunks, bumps, excessive vibration is not normal, and any competent dealer should be able to debug and resolve.
Further, note, the transfer case only holds about 1 quart of fluid...so if you are constantly engaging the cluthes, etc, you are probably due for more frequent transfer case fluid changes than the manual specifies.

You are going to have to train the wife...this is not an AWD vehicle, it is a 4WD vehicle...and has to be driven as such.

After reading through the thread I was going to comment and he summed it with that last comment. I agree your wife’s previous Land Rover is a completely different rig to drive given that it’s an all wheel drive transfer case. The Yukon’s four wheel drive transfer case is completely different and there’s a learning curve going from 4WD to AWD on how to best manage traction. I had to learn that myself going from a dodge Durango with 2Hi, 4Hi, and 4Lo setup to my full time AWD gmt800 Yukon Denali.

 

[mb1500]

Thank you all for your responses.

I'd like to make one thing clear here to everyone. I am NOT talking about ANY NOISE. From a noise standpoint I can tell a difference between any of the settings.

I am talking about feelings of stutter, surges, vibrations, rumbles, shakes, etc. They are small but absolutely are there and were not there previously. It almost feels like the truck is switching gears 5-7 times between each actual gear shift.

Put it in 4wd HI , drive in a straight line and post if the hesitation goes away or not.

 

[DuraYuk]

AUTO turns it into an ALL WHEEL DRIVE. Many All Wheel Drive Vehicle on the road so those that say to not use it are offering personal opinion not based on factual informatiion.

AUTOMATIC TRANSFER CASES
The last category is a combination of 4WD and On Demand AWD. These transfer cases have a 2HI, Auto-4WD, 4HI, 4LO and Neutral position and would fall in the general 4WD category. This transfer case has the operating characteristics of both an On Demand AWD and a Part-Time 4WD system depending on the mode selected. This transfer case uses a clutch pack to allow for a difference in speed between the front and rear axles in the Auto-4WD mode. In the 4HI or 4LO modes, there is no allowance for the difference in speed between the front and rear axles. An example of a vehicle with this would be a Sierra with a push-button transfer case with a 2HI, Auto-4WD, 4HI, 4LO, and Neutral positions.

Factual information from the manual:
AUTO (Automatic Four-Wheel Drive)
Use when road surface conditions are
variable. When driving in AUTO, the front
axle is engaged, and the vehicle's power is
sent to the front and rear wheels
automatically based on driving conditions.
This setting provides slightly lower fuel
economy than 2 high.

 

[Stbentoak]

Factual information from the manual:
AUTO (Automatic Four-Wheel Drive)
Use when road surface conditions are
variable. When driving in AUTO, the front
axle is engaged, and the vehicle's power is
sent to the front and rear wheels
automatically based on driving conditions.
This setting provides slightly lower fuel
economy than 2 high.

yes, It is not “all wheel drive“. It’s all wheel drive when it detects slippage then it becomes all wheel drive. Intermittently, in and out as needed. The front drive train is not engaged until slippage is detected even though it’s in auto.
“All wheel drive” implies that it’s all wheel drive all of the time….dry, or slippery, ice or asphalt. That simply is not what this is.

 

[BlaineBug]

Is this the same symptom? > > https://www.tahoeyukonforum.com/threads/4wd-auto-problem.139109/unread