50-60mph... Bit of jolt when accelerating after coasting -- normal?

[KATfishing]

Hi - 2008 Yukon Denali 6.2L AWD. Transmission is nice and smooth when accelerating from 0-70mph. However when I am driving at 65 or so and coast or slow down to 50 and step on the gas, I get slight lag followed by a bit of a jolt. It only happens in this range of 50-60 mph. If I'm very light on the gas it's not as noticeable. I'm sure there is an explanation. I'm wondering if it has to do with transfer of power, locking differential or something other than transmission. Sorry, I'm a novice. Transmission seems smooth in all other circumstances.

 

[Doubeleive]

you could just be feeling the v4 to v8 mode kick in, but it could be a combination of that and other issue's also, I disabled mine with a tune. you can kind of inspect it underneath by getting under there and feeling if the driveline has any play or u-joints, if jiggles or moves a bit that's a sign of something worn. if you want to disable the v4 mode its going to take 200-300 dollars for a tuner that allows you to turn that feature off.

 

[KATfishing]

you could just be feeling the v4 to v8 mode kick in, but it could be a combination of that and other issue's also, I disabled mine with a tune. you can kind of inspect it underneath by getting under there and feeling if the driveline has any play or u-joints, if jiggles or moves a bit that's a sign of something worn. if you want to disable the v4 mode its going to take 200-300 dollars for a tuner that allows you to turn that feature off.

Thank you - This is really good info. I'm taking it in next month for fluid changes (transmission, diff, transfer case) and will have a full inspection pointing that out. I have about 6K left on a warranty that would cover u-joints, suspension, transmission, etc. I guess it would be a good time to have it checked while still under warranty.

 

[lamerem]

What tuner are you using? Also, have you noticed any noticeable difference in power and/or fuel mileage.

 

[jtbadowski]

Motor mount...

 

[KATfishing]

What tuner are you using? Also, have you noticed any noticeable difference in power and/or fuel mileage.

After coasting the down to about 50 mph, I notice a bit of a lag/loss of power after stepping on the accelerator and that's when I get a jolt of power sometimes with a "clunk" that feels underneath the vehicle, although that could be perception on where it's coming from. I don't own a tuner.

 

[KATfishing]

Motor mount...

That could explain the "clunk" when there's a shift in momentum after the lag in acceleration.