Exhaust drone?

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After months of exhaustive searches and $$$ replacing various engine components, would appear my "rough idle" is actually exhaust drone. Is anyone else familiar with this issue??
 
At IDLE RPM?!?!?

Usually, exhaust systems do not resonate at such a low frequency.

Typically, build a Helmholtz exhaust resonator to fix the issue.
 
How did you diagnose? Usually a rough idle will have the engine shaking under the hood. So open hood, vehicle chocked and in gear at idle and you can see the engine moving. If it's sitting still, it's something else ...
 
Aside from the cheap aftermarket replacement exhausts, this can also happen with gutted catalytic converters. Is it the Escalade or the Maximia?
 
Its the Escalade 6.0 AWD. OEM exhaust. Brand new catalyst. And apparently the OEM exhaust is partly to blame. Because some claim to get rid of the moan/drone using a rerouted aftermarket exhaust for huge money. The area that wraps from the driver's side over the transmission pan vibrates for some like me. Got worse after the new 3 way cat was installed by dealer. Its real throaty, many would love it. I hate all that noise and vibration. I knocked that area it with a rubber mallet, feels just like what I feel at the gas pedal.

Supposedly 2 of these weird things hanging off the exhaust helps.




I also found this which refers to the issue

Document ID# 1820205
Subject: Exhaust Vibration,Resonance,or moan.
Also look for #PIP3121E (04/24/06)
Includes:
01-06Cad Escalade
02-06 Chev Av
99-06 Chev Silv
00-06 Chev Sub, Tahoe
99-06 GMC Sierra
00-06 GMC Yukon
03-06 Hummer

Condition is listed as "some 99-06 with single exhaust system may exhibit exhaust vibration that is engine load sensitive. Typically, this will happen just off idle to 2000 RPM on light acceleration."
 
Have you crawled underneath to look at it? The exhaust could be rubbing on something.
 
Oh yeah, I think I know exactly the drone you are talking about now. I never had anyone complain about it, so I never had to fix it. I have seen those vibration damping weights on some models. That is probably a good fix as long as the weights are designed for this specific application.
 
Originally Posted By: Nick1994
Have you crawled underneath to look at it? The exhaust could be rubbing on something.

Oh yeah. I know every inch of that truck. My baby. She's clean under there. The exhaust is very close to a mount. But thats supposedly normal. Other than that a rubber muffler mounting bracket has a small tear. The rest has no rust, like new.
 
I would go with the exhaust weights: cheap fix. Not sure why you would need 2 though, but whatever others have claimed works, I would do that and be done with it.
They are just painted , so I would not expect them to last more than 5 years.
 
It has a tach. It does happen 1800-2k rpms under certain conditions. Vibration runs right up your leg.. lol
 
LOL, your issues wan't "acoustic drone", you are experiencing an unintentional mechanical harmonic.

Try the weights - they are cheap.

ANY amount of mass WILL affect the frequency that the harmonic occurs.
 
Given you're attempting to quiet a pipe resonance, where you locate those dampeners along the pipe is critical: They need to be at a node rather than anti-node.

If it's still noisy/vibrating, they're in the wrong location.
 
Originally Posted By: Linctex
LOL, your issues wan't "acoustic drone", you are experiencing an unintentional mechanical harmonic.

Try the weights - they are cheap.

ANY amount of mass WILL affect the frequency that the harmonic occurs.

LOl whatever its called, its worse now that its cold out. That pipe and its catalyst was replaced by the dealer, and its been bad ever since. Should i try backing off on the manifold bolts and tightening back down again?
 
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