Bad Catalytic Converter?

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OR VietVet

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Let us know how it goes. If you get the catalytic convertor replaced at that shop or any other related repair, make sure you ask for credit for the work that did not fix it the first time in the shop. Make sure all is documented.
 
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nick0789

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Update: the owner of the shop spent a good hour looking over the exhaust with the tech the did the original repair attempt. They went over everything from the exhaust manifold bolts down to the muffler hanger and he did not find anything [extremely] obvious as the culprit.
He said that most likely that the passenger cat is at the early stages of failure (either substrate separating or cracking) since the noise is not present at cold starts, and only once everything gets warm to hot. With no codes being thrown and the noise being minimal at the moment, he suggested to either let it go for now and repair once it gets worse ... or put a new cat on at around $350.

I'll go ahead and order the exhaust and oxygen sensors off of RA sometime soon and report back once I have the time to get to the repair.

Side note: I always figured cats to be expensive, but the price difference between RockAuto and a brick-and-mortar store is ridiculous. $400 on RA vs. $500 on Summit vs. $800 at Advance.
 
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nick0789

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Additional questions:

There is not a gasket at the end of the y pipe where it connects to the muffler, right? So I just need two gaskets?

As far as the driver's side gasket goes, am I better off with the plain ring style or the flat (clothes iron) style?
 

George B

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Additional questions:

There is not a gasket at the end of the y pipe where it connects to the muffler, right? So I just need two gaskets?

As far as the driver's side gasket goes, am I better off with the plain ring style or the flat (clothes iron) style?
I would prefer the cloth iron style with a ring in the middle. Better alignment when you reassemble.
 
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nick0789

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Thanks!

I went to order the Walker exhaust from RA ($400) and they were wanting to charge $160 to ship that portion of the order. Amazon had the same setup for $480 after tax and shipping (thanks Prime!) so just in case anyone else goes down this route you'll save ~$100 just going with Amazon for the exhaust. RA was still cheaper for the sensors and gaskets, though, so I went with them for those.
 
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OR VietVet

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At Ra, you are dealing with no additional middle man. Make sure to read all RA descriptions and what you are getting, includes needed gaskets or not? Check all the disclaimer application notes. I gave you your application numbers but I did not look to see what gaskets may be needed, if any. The owner sounds correct about his diagnosis. The noise sounded to me, as I think I said, that it was just the start of an internal cat problem but look very close at the shields. If you let it go, that debris may get in the mufflers and damage the muffler. As I also said, good call on doing the sensors at the same time. Remember, at RA, the shipping adds on too and the size and shape of the cat pipes assembly can be up there but the RA site tells you what it will be.

I just read your response about ordering parts. Make sure to post results after the replacements.
 
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nick0789

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It’s going to the shop tomorrow, thanks to two very stubborn Y pipe nuts that refused to budge even with some bullying by ole trusty (AKA my dewalt impact).
I'm just glad I tried breaking those nuts free before using the sawzall to remove the existing pipes.
 
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nick0789

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Update

I just picked up the tahoe from the shop. No more buzzing noise. Throttle response is improved a little, based on the calibrated seat of my pants. Exhaust sounds cleaner as well.

Aside from the smell coming from underneath the vehicle, thanks to leftover sticker adhesive and manufacturing oils/lubricants, I'm pleased with the results. I'll try to clean up the bulk of the sticker residue when I get home and just let the rest burn off.

Thanks everyone for the help!
 

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