Serge, while driving...

[Denali239]

I have a 2007 Yukon Denali XL with 27,500 miles on it. My wife and I just got back from a 600 mile weekend road trip and on the way home I noticed the truck surging/jerking every now and then when I was going around 75-80mph. It almost felt like the compressor kicking on and off but very harsh. It felt like it was coming from the transmission area. Didnt feel like an engine misfire but I'm kinda at a loss. I would appreciate some thoughts. Thank you.

 

[Rockytfox]

It sounds like maybe the trans was trying to determine which gear to get into. Did you notice any fluctuation in the rpms?

 

[iwaslowr]

I thought there would be a pic of Soulsea driving (literally) in here based on the title of the thread...

 

[LuSe4]

I thought there would be a pic of Soulsea driving (literally) in here based on the title of the thread...

Omg, I thought the same thing!

 

[07Burb]

X3 on the Soulsea thing

Back on topic....sounds like it was the fuel management system going from 4 cylinder to 8 cylinder to 4 cylinder mode

 

[soulsea]

You need a serge protector.

 

[Denali239]

Thank you for your responses, sorry if the title was misleading to some I wasn’t sure exactly how to explain it. The RPM didn’t fluctuate when this occurred, and please correct me if I'm wrong but I do not think the 07 model came at the cylinder deactivation on it. I'm really at a loss to what this could be.

 

[07Burb]

Thank you for your responses, sorry if the title was misleading to some I wasn’t sure exactly how to explain it. The RPM didn’t fluctuate when this occurred, and please correct me if I'm wrong but I do not think the 07 model came at the cylinder deactivation on it. I'm really at a loss to what this could be.

My 07 has fuel management ("cylinder deactivation") on it and does something similar to what you're describing. I was worried about it too until I decided to investigate further and flipped my DIC where I could monitor when it was using all 8 cylinders and when it'd move to just using 4 cylinders. I was able to determine that when I felt the "serge" happen was exactly when it was moving between modes. You might check it out. Not saying its for sure the root of your issue but it's easy to determine if it is before you spend money on parts or diagnosis.

 

[sumo]

You need a serge protector.

THIS x1000

did you check trans fluid level?

 

[Wakinvol]

It is the displacement on demand. 8 vs 4 cylinder mode

 

[felixgun]

Yea Jacob the 07 Avy/Tahoe/Burb/Yukon came with AFM but it wasn't until 08 or 09 for it to be released on the 6.2L Yukon Denali, then not until 2010 for Esky's to get it. Since my Esky is an 07 I don't have it which is probably why i'm getting 11.1 mpg.

 

[Diabology]

I thought there would be a pic of Soulsea driving (literally) in here based on the title of the thread...

x4

 

[KMeloney]

Same issue here, but most noticeable @ 30 mph. I have referred to it as "bucking" in other threads. I think it's a trans thing, and not a fuel management issue. But, then again, I don't know if the two are separate.

 

[Goodinblack]

X5.

What ^^^^^ KMeloney said. I experience too.... Have you found a fix for it or is it just "normal" ?

 

[Denali239]

Yes bucking is a great way to describe it. Thank you for the advice. I will be checking the trans fluid later on today. I contacted the dealer and they confirmed the 6.2 in 07 does not have displacement on demand so I can rule that out. I have an extended warrany on the truck, however I dread taking it to the dealer for something that isnt consistant because 99.9% of the time they say everything is normal.

 

[KMeloney]

I haven't gotten mine to the dealer yet. I, too, suspect they'll say it's normal -- and that's why I'm trying to get as much info about it at possible first.

 

[mike1944]

Yea Jacob the 07 Avy/Tahoe/Burb/Yukon came with AFM but it wasn't until 08 or 09 for it to be released on the 6.2L Yukon Denali, then not until 2010 for Esky's to get it. Since my Esky is an 07 I don't have it which is probably why i'm getting 11.1 mpg.

You aren't missing much. I played with my 2010 Denali quite a bit on one long trip.

It usually only kicked into 4 mode when it was a constant speed, below 45 mph, and it was flat or downhill. Higher speed or any grade, no matter how slight, would pop it back into 8.

There was no noticeable kick/noise/surge/etc. when it did change.

 

[GM Customer Service]

Yes bucking is a great way to describe it. Thank you for the advice. I will be checking the trans fluid later on today. I contacted the dealer and they confirmed the 6.2 in 07 does not have displacement on demand so I can rule that out. I have an extended warrany on the truck, however I dread taking it to the dealer for something that isnt consistant because 99.9% of the time they say everything is normal.

Please keep us posted of the results of your dealer visit.

Please feel free to contact me if you have additional questions.

Louis
GM Customer Service