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Posted

From the reports in this thread, AFM would not be the direct cause. It is your truck and you can do as you please; but, I wouldn't be shutting off AFM. First step would be to remove the fuse providing power to the radio/amplifier(s). That is simple and something you can do. If that solves your problem you could ask your dealer to turn off Active Noise Cancellation.

Posted

Just remember -- Pulling the AMP fuse at first did NOT help the initially ride for me. I still felt the pressure actually a little worse.. After I reinstalled the fuse and did the windows and sunroof, the truck sat for about an hour before I hopped back in it to go back out. That last ride felt completely different -- and till this day, it has changed the entire feel inside the cabin.

 

It seem to have changed something for me, I REALLY hope it does for someone else, too!!

Posted

I have test driven every model of this vehicle in the past week, and all of them have had this rumble. Today I drove a 2015 Yukon XL that I had hoped to buy. I set the cruise at 60 km/hr and watched what happened. When the engine switched to V4 mode, the rumble began. I think that the problem occurs at 1100 rpm in v4 mode. I am sure that it is a resonation occurring in the drivetrain due to the engine lugging at low rpm, and ends up sounding as a rumble in the drive shaft or differential. I was extremely disappointed by this as I was set to buy. I set the cruise at 70 km, 80 km , same thing ... a rumble started whenever the engine switched to v4 mode. Very glad that I drove again. Now I will not buy this vehicle. It's not wind noise, active noise cancel , or loose roof liner, its resonation due to engine lugging. Switching to tow/haul or manual stopped the problem at these low rpm.

Posted (edited)

I have test driven every model of this vehicle in the past week, and all of them have had this rumble. Today I drove a 2015 Yukon XL that I had hoped to buy. I set the cruise at 60 km/hr and watched what happened. When the engine switched to V4 mode, the rumble began. I think that the problem occurs at 1100 rpm in v4 mode. I am sure that it is a resonation occurring in the drivetrain due to the engine lugging at low rpm, and ends up sounding as a rumble in the drive shaft or differential. I was extremely disappointed by this as I was set to buy. I set the cruise at 70 km, 80 km , same thing ... a rumble started whenever the engine switched to v4 mode. Very glad that I drove again. Now I will not buy this vehicle. It's not wind noise, active noise cancel , or loose roof liner, its resonation due to engine lugging. Switching to tow/haul or manual stopped the problem at these low rpm.

 

Personally I think the two issues are related. There is something "off" with the interior cabins of these vehicles. Not sure if it is the way they are sealed up or if the Active Noise Cancellation has something to do with it, but as another person commented, you feel like you are in a cave.

 

I think the pressure issue is there all the time. Trucks that have a drivetrain vibration/resonating might cause the buffeting (pressure in ears) effect to be magnified in the cabin. That could explain why some people are hearing (feeling) it more than others.

 

Just my two cents.

Edited by yukontruckman
Posted (edited)

I know GM monitors this thread. Why won't you (GM) chime in with some insight?! Some of us got our money back because of the problem. You would not have given our money back if there was not a problem. Why are you making people pull out fuses trying to resolve this legitimate issue. I bet you will void the warranties of these people trying to fix your troubled 2015 platform.

 

I have tried to remain positive towards GM and remain loyal to the only brand my entire family has ever known--3 generations! I am seriously questioning my judgment in sticking by GM. I have not taken delivery of my $78,000 vehicle on order. Do you really want my business? If so, make us feel like it. What is going on?!

Edited by jasondenali15
Posted (edited)

I saw a reference to a problem at 800 RPM and above at 1100 RPM. 800 RPM equates to 13Hz whilst 1100 RPM is 18Hz. 13Hz would require a large amount of energy behind it to be "heard" in the rare case of someone who could "hear" that frequency...at 13Hz the experience is tactile. 18Hz is on the border line, and if I recall, would require on the order of 90 dB SPL in order to cross the threshold of hearing. It is possible, as well, that harmonics of those frequencies could be audible. It is also possible (I am not going to build an acoustic model of a Yukon) that such vibrations could create a resonance inside the cabin and equally possible that minor changes in size/mass resonating materials in the vehicle could explain the hit/miss with respect to buffeting in some and not in others.

 

Active Noise Cancellation (ANC) can cause a pressure sensation in the ears ... word of choice is 'can' not 'will' ... but not the "buffeting" sensation as described here. HOWEVER ... ANC gone awry or poorly implemented can create that sensation. Each location in the cabin would experience a slightly different sensation. You can remove the fuse to see if that helps the issue or have a second person in the car move to different seating locations and determine if the effect changes (in some cases, just moving your head six to eight inches could result in a difference in the buffeting effect).

 

Do not expect GM to admit to a problem until (a) they determine it is a problem; (b), determine the cause; and, © have a solution. Out of 1,000 (or more) vehicles per day being dumped out of Arlington and only a couple hundred of people reporting an issue, GM could easily decide they don't have a problem (we don't know how many have actually reported this issue to GM).

 

Some are pointing to AFM. Just on the surface, I find that a less likely cause. When the engine goes from V8 to V4, RPM doesn't change. The amount of rotational mass in the vehicle doesn't change nor does the speed. Is the engine lugging at 1100 RPM in V4 mode? No. With AFM and an automatic transmission, one of two (or both) things will occur: (1) engine will go from V4 to V8 mode; or, (2) the transmission will shift to a more appropriate gear. Exactly what one would expect with what we call in aviation as FADEC (Full Authority Digital Engine Control). [Auto guys pay less for their engines so you don't need to have a super fancy name to justify the higher costs.]

 

EDIT: BTW, ANC is not going to be working at 13 Hz nor 18Hz to begin with.

Edited by Anon2015
Posted

Hi Andraya. Any update from the GM folks? This has got to be something simple i would guess and i still have a check ready and willing to buy a new yukon. Any sort of status update would be welcomed. I think folks on here would applaud a direct line of communication with folks working on this so our faith in GM is restored. Are they afraid to talk with us about it? The biggest frustration is GMs silence here.

Posted

Well, whatever it ends up being, I'm glad that I found this thread. I'll look forward to seeing what the answer is to these/this problem(s). I wanted to buy today or tomorrow. Not now. I drove short Denali, long LTZ, short LTZ, long XL with standard wheel size, they all had same problem. Thanks to previous posters. Saved from a $75000.00 mistake.

Posted

I haven't had much of a chance to fiddle with this on our Yukon XL. Haven't pulled the fuse on the audio system. I assume the ANC "simply"is built into the audio system. Here is a question - does anyone jnow if the ANC stays on when the audio system power is turned off with the power button on the dash? Of course, the crappy owners manual gives virtually no details.

 

We did go for a short drive last night and I was turning the Tow/Haul mode on and off and I want to think that it made a noticeable difference. The "buffeting" seems to dimish a fair bit when in Tow/Haul mode. I didn't drive it for very loing so this is not a for sure observation, but may be a factor. If so, then it certainly points to the power train.

 

Also, there was no correlation to V8 or V4 mode. I did not perceive any change in either, and they did not switch with Tow/Haul mode (although, the transmission shifts to a lower gear much quicker).

 

Next step is to pull the fuse and see what happens. I also plan to take some vibration, sound, and pressure readings inside the vehicle to determine what frequency this is occuring at and the amplitudes. Hopefully this weekend.

Posted

You guys are smarter than i am. Figuring out the sound issue one test at a time. I wanted to just drill a hole in the back door to let the pressure out. Wife said the dealer probably would not appreciate it. Looking forward to a resolution.

Posted

Andymac, don't drill any holes! Omg!

 

Seriously, though, I opened windows and surprisingly the buffeting was still there. At least until the wind noise from a fully open window took over. But it tells me this is not a simple "pressuring up" up of the cabin, as even opening one window an inch should have bled off any kind of pressure build up. Now, actual buffeting is a complex aerodynamic effect which can actually be one of several different phenomenon, depending on the vehicle. I'm thinking what we are hearing/feeling seems like buffeting but is in fact something else that happens to sound similar.

 

You know, exhaust drone can be a real bugger. My 86 Corvette was unbearable after I installed an aftermarket "performance" exhaust. The drone at 60 mph was so terrible that I essentially stopped driving it. I am seriously suspect of that crazy muffler on these vehicles with the valve that opens and all that. Did GM really do the research to make sure there isn't something resonating with the exhaust and the body. Has anyone had the optional Borla exhaust put on? That might be interesting.

Posted

Going to test a new 2015i today in hopes of a resolution. Otherwise we may have to consider going back to a 2014 if I can find one. One interesting fact ... I had test driven a Tahoe LTZ last week which was a 2015 dealer trade from NJ. After driving it I didn't notice the pressure as much but I did notice that the windshield had the same circular marks on the inside of the windshield on both sides and one in the middle. As I had posted before our 2015 Suburban had these same marks after the GM engineer took it apart for the second time..... Dealership didn't have a clue or they refused to divulge any inside info. I hate to say it but we might end up in a F$#^.

Posted

Like JSM I was going to purchase 2015 yukonxl denali until I discovered this site, talking to local dealers around Hamilton area which treat you like this is not an issue I became disgusted. Iam now seriously looking at infiniti QX80 plus a new ford p.u. Like others I feel GM is well aware of this problem and does not have a solution so they do not reply. I contacted them in the recent past and received a smoke and mirrors reply. This site has saved me a lot of future agravation and also money as it appears.

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