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Oh sure, ask the Canadian to crawl under his truck in January! ;) I will be rolling through the Virginias in a month or two on my way to Florida - got a lift?

 

Next chance I get, I'll take a closer look and will snap some more pictures.

 

--

Marc

Ha...No worries. Maybe Ozzii can chime in with the locations.

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You should have the mod make this a sticky; what's happening is every few months as users churn, and new people arrive here, this info gets lost

 

The booming and buffeting are similar, but treated differently.

They are both related to the poor sheet metal on the trucks, hence why GM can't fix it unless they redesign the vehicle.

1) The buffeting is related to the upper sheet metal vibrating due to an imperfect ride. The stiff body mounts contribute to it making the vibrations in the metal harmonic in nature causing the steady buffeting sound at 40 mph and up. The made the body mounts on the 2017 slightly improved, but it didn't help enough to eliminate the issue.

The only fix for this is to isolate the roof sheet metal like some have done by placing inserts under the roof rack cross bars or by reducing the amount of harmonic vibrations into the truck from the wheels/tires through the body mounts to the sheet metal.

This fix has consisted of getting better tires and getting RFB number below 15 lbs.

2) The low speed booming is also a sheet metal issues, but specifically the sheet metal under the truck. Poor roads that have a lot of bumps cause the exhaust to jar up and down making the lower end sheet metal flex creating the boom. The booming is because the interior of the truck is extremely air tight, so you're getting a boom similar to a bass drum.

The fix for this is to reduce the jarring from the exhaust. Hence the dampers/ weights.

This is why the fix also works on 6.2L like FogDuckers and a 5.3L like Ozii's.

3) In addition to this, the 5.3L exhaust's flapper valve is also causing a harmonic vibration due to its location so tight to the underbody sheet metal.

In V4 mode, the flapper adjusts changing the pressure under the cab. That pressure and it's vibration also creates a buffeting sound.

Hence why there's a bulletin for the replacement of the exhaust on the 5.3L. but the buffeting will just return like on Leslie's Yukon.

The only real fix is to drive in M5 or M7 mode to shut off the V4 AFM. Or get a range device to shut off the AFM permanently.

The 6.2L, which is only in a Denali, comes with the Active Noise Cancellation, and the ANC reduces this V4 buffeting, hence why the exhaust replacement only applies to the 5.3L and the testing and repair of the ANC only applies to 6.2L.


There other vibrations on the trucks, but they are on a case by case basis, such as on FogDuckers rear axle.

But all in all, this is all caused by lighter weight sheet metal that flexes more tham usual, and was installed for the purposes of saving gas.

The real fix won't come until a design refresh.

And every Yukon and Suburban and Escalade has the same issues. On some it's not as bad and for others, it just doesn't bother them as much.

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3) In addition to this, the 5.3L exhaust's flapper valve is also causing a harmonic vibration due to its location so tight to the underbody sheet metal.

 

In V4 mode, the flapper adjusts changing the pressure under the cab. That pressure and it's vibration also creates a buffeting sound.

 

Hence why there's a bulletin for the replacement of the exhaust on the 5.3L. but the buffeting will just return like on Leslie's Yukon.

 

The only real fix is to drive in M5 or M7 mode to shut off the V4 AFM. Or get a range device to shut off the AFM permanently.

 

The 6.2L, which is only in a Denali, comes with the Active Noise Cancellation, and the ANC reduces this V4 buffeting, hence why the exhaust replacement only applies to the 5.3L and the testing and repair of the ANC only applies to 6.2L.

 

What is the bulletin number for the exhaust replacement? Has anyone else on the forum other than Leslie had this done? Strange that it would solve the vibration problem, only to have it return later..

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What is the bulletin number for the exhaust replacement? Has anyone else on the forum other than Leslie had this done? Strange that it would solve the vibration problem, only to have it return later..

PIT5404C (should be on revision C now)

 

This is not a ride quality vibration were discussing here. These are harmonic vibrations that introduce buffeting and booming into the cab.

 

The exhaust V4 AFM flapper on the 5.3 adjust and changes the back pressure of the exhaust to compensate for the lower combustion of 4 cylinders versus 8.

 

This back pressure drone, causes a harmonic vibration which introduces the buffeting.

 

This is additional buffeting above and beyond the RFB vibration which also causes buffeting.

 

Replacing the exhaust, does nothing because the AFM will continue to change the V4 v8 management, changing the back pressure, changing the drone, causing the buffeting.

 

The only way to stop this form of buffeting is driving with the AFM off.

 

See the PIT...Once of the diagnostics is switch the AFM off and seeing if the buffeting persists.

 

If the buffeting goes away, it a normal function of the vehicle cause by AFM.

 

This does not apply to the 6.2 because of the Bose ANC.

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PIT5404C (should be on revision C now)

 

This is not a ride quality vibration were discussing here. These are harmonic vibrations that introduce buffeting and booming into the cab.

 

The exhaust V4 AFM flapper on the 5.3 adjust and changes the back pressure of the exhaust to compensate for the lower combustion of 4 cylinders versus 8.

 

This back pressure drone, causes a harmonic vibration which introduces the buffeting.

 

This is additional buffeting above and beyond the RFB vibration which also causes buffeting.

 

Replacing the exhaust, does nothing because the AFM will continue to change the V4 v8 management, changing the back pressure, changing the drone, causing the buffeting.

 

The only way to stop this form of buffeting is driving with the AFM off.

 

See the PIT...Once of the diagnostics is switch the AFM off and seeing if the buffeting persists.

 

If the buffeting goes away, it a normal function of the vehicle cause by AFM.

 

This does not apply to the 6.2 because of the Bose ANC.

 

I agree it is more of a harmonic vibration. For me it generally occurs between 30 and 50 mph, with slight pressure on accelerator, in V4 mode. We never feel (hear) it at highway speeds, >50 mph, even in V4 mode.

 

Fortunately the truck doesn't appear to have any of the other issues mentioned...booming, buffeting, ear pressure, even after 23k miles. Maybe it's because it has 18" wheels? I could be I just don't notice it, but I'm pretty sensitive to noise. Ask my kids :D

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The booming and buffeting are similar, but treated differently.

 

They are both related to the poor sheet metal on the trucks, hence why GM can't fix it unless they redesign the vehicle.

 

1) The buffeting is related to the upper sheet metal vibrating due to an imperfect ride. The stiff body mounts contribute to it making the vibrations in the metal harmonic in nature causing the steady buffeting sound at 40 mph and up. The made the body mounts on the 2017 slightly improved, but it didn't help enough to eliminate the issue.

 

The only fix for this is to isolate the roof sheet metal like some have done by placing inserts under the roof rack cross bars or by reducing the amount of harmonic vibrations into the truck from the wheels/tires through the body mounts to the sheet metal.

 

This fix has consisted of getting better tires and getting RFB number below 15 lbs.

 

2) The low speed booming is also a sheet metal issues, but specifically the sheet metal under the truck. Poor roads that have a lot of bumps cause the exhaust to jar up and down making the lower end sheet metal flex creating the boom. The booming is because the interior of the truck is extremely air tight, so you're getting a boom similar to a bass drum.

 

The fix for this is to reduce the jarring from the exhaust. Hence the dampers/ weights.

 

This is why the fix also works on 6.2L like FogDuckers and a 5.3L like Ozii's.

 

3) In addition to this, the 5.3L exhaust's flapper valve is also causing a harmonic vibration due to its location so tight to the underbody sheet metal.

 

In V4 mode, the flapper adjusts changing the pressure under the cab. That pressure and it's vibration also creates a buffeting sound.

 

Hence why there's a bulletin for the replacement of the exhaust on the 5.3L. but the buffeting will just return like on Leslie's Yukon.

 

The only real fix is to drive in M5 or M7 mode to shut off the V4 AFM. Or get a range device to shut off the AFM permanently.

 

The 6.2L, which is only in a Denali, comes with the Active Noise Cancellation, and the ANC reduces this V4 buffeting, hence why the exhaust replacement only applies to the 5.3L and the testing and repair of the ANC only applies to 6.2L.

 

 

There other vibrations on the trucks, but they are on a case by case basis, such as on FogDuckers rear axle.

 

But all in all, this is all caused by lighter weight sheet metal that flexes more tham usual, and was installed for the purposes of saving gas.

 

The real fix won't come until a design refresh.

 

And every Yukon and Suburban and Escalade has the same issues. On some it's not as bad and for others, it just doesn't bother them as much.

 

Thanks for the summary. In our suburban I experience what I would describe as a pressure on your ears, similar sensation to changing altitude in a plane but this is constant, causing ear fatigue. Is that what you are calling buffeting, or is that something different?

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Thanks for the summary. In our suburban I experience what I would describe as a pressure on your ears, similar sensation to changing altitude in a plane but this is constant, causing ear fatigue. Is that what you are calling buffeting, or is that something different?

That's buffeting.

 

The fix is all new stronger sheet metal and hydraulic body mounts to absorb harmonic vibrations.

 

Since that not happening, you next best is to reduce the vibrations from the road through soft, better quality tire, and low road force balancing.

 

I suggest Michelin Premier LTX RFB below 15 lbs.

 

That's what worked for others.

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Posted (edited)

Yep, I went with the michelin premier LTX wrapped on the denali 20" wheels and made sure to RF under 15lbs and it took care of 90% of the buffeting. I'm tempted now to go back to the 22s again but with michelin defenders/premier ltx's this time. When I was running the 22s, they still had the oem bridgestones with about 40% tread remaining, so I'm pretty certain that crappy tires was the issue.

Edited by ajs800
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What is the bulletin number for the exhaust replacement? Has anyone else on the forum other than Leslie had this done? Strange that it would solve the vibration problem, only to have it return later..

 

My Yukon has never had a physical vibration issue. It has the severe buffeting, ear pressure issue when in v4 mode. I just always drive in M now. Annoying and lessons my MPG, but it somewhat makes the sensation tolerable.

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My Yukon has never had a physical vibration issue. It has the severe buffeting, ear pressure issue when in v4 mode. I just always drive in M now. Annoying and lessons my MPG, but it somewhat makes the sensation tolerable.

Sorry for all the questions. Does your Yukon exhibit the buffeting at any speed in V4 mode? As I mentioned before, my Suburban produces the buffeting noise on local roads, in V4, between 30-50 mph. On the highway/interstate, no buffeting, even in V4.

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Is there a bulletin number or anything to point my dealer to? I am planning to take it in this week for maint, steering wheel bulletin, and would like them to explore the booming fix, even if it is out of pocket initially. I would like to be able to provide a number or something for them to reference. Thoughts?

 

Thanks!

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  • Why isnt GM addressing this issue. Wide spread media is covering this matter, but yet, no one from GM is speaking up. 3 years later, uhhhh I know you guys went threw a buy out, government overhaul so to speak, but now your selling your loyal customers out, and soon you will lose them if you do not speak up. I am on the fence frankly, whether I buy another GM again. This isnt just on the Suburbans, Yukons, Tahoes, etc... its on the trucks as well as other vehicles. this is what happens when a government entity takes over the company and starts running it with a bean counter mentality. Oh boy.... This has to be hitting the bottom line for GM. Yeah, I see there numbers are cranking on the global market, stock market, and they are meeting expectations, but think if this issue did not exsist, You have to wonder what numbers GM would be doing then. Get a clue GM. FORD in my opinion makes a far superior product, and was never bought out or bailed out by the government, there for quality never compromised by cuts because of the bail out. just goes to show you, governments entities do not belong in the world of owning companies, they are a regulator only, and thats questionable and subjective for sure. I would be curious if GM had the balls enough to chime in these blogs, and give there loyal customers peace of mind, and address this matter, letting all know that they are working on mitigating or addressing the issues, for future production. My wife and I were gung ho to buy a Suburban, until I just so happen to stumble across an internet blog about a vibration issue with this model, then after doing further research, there is 8,750 TOPICS of this issue since late 2014. about the time when the new 2015 production come out to the public. man, this has to be hitting the bottom line for GM. If FORD was smart, they would bring back the excursion, diesel. I would buy it in a heat beat. If GM doesnt address this issue, or gives us a answer whether or not they will buy it back if just so happen to buy one of these SUVs and it has a vibration or buffeting issue, we are not even entertaining buying it. why would i wan this heartburn. just saying..... GM?

 

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My Yukon has never had a physical vibration issue. It has the severe buffeting, ear pressure issue when in v4 mode. I just always drive in M now. Annoying and lessons my MPG, but it somewhat makes the sensation tolerable.

It sounds like you couldn't get the car replaced. I was just contacted by BBB yesterday and I am taking it to them for an informal hearing with GM as soon they schedule that for me. What happened to your case?

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It sounds like you couldn't get the car replaced. I was just contacted by BBB yesterday and I am taking it to them for an informal hearing with GM as soon they schedule that for me. What happened to your case?

I had my exhaust replaced 2 x's. Engine mounts replaced. Roof checked. Nothing solved my buffeting issue. They offered to make a car payment for me and told me there was nothing else that they could do for me. I don't not have the time to do all the leg work for a lemon law. I have to drive with my Yukon in manual to prevent myself from feeling sick from the buffeting. $65k for a truck that I can not drive they way it was meant to be driven. So basically GM beat me down and won.

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Sorry for all the questions. Does your Yukon exhibit the buffeting at any speed in V4 mode? As I mentioned before, my Suburban produces the buffeting noise on local roads, in V4, between 30-50 mph. On the highway/interstate, no buffeting, even in V4.

Basically the same as yours. Buffeting from 25-55 while the Yukon maintains it's current speed while in v4 mode. The second it goes to V8 the awful buffeting/pressure goes away for the most part

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