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Discussion Starter · #1 ·
Hey guys,

So I was driving out to the supermarket about 30 minutes ago... started it up, drove about 1/2 way, and I noticed that my exhaust became a bit "boomier"... Hell: a LOT more boomy and hollow sounding. Didnt think much of it and drove to the ralphs, popped the hood, nothing seemed wrong... no burning, smoking, etc.

Then I got my two gallons of distilled water (chanign coolant tomorrow, among other things) and got back in the car...

Started it up and started driving, the boominess and hollow exhasut was still there, but now there is almost what could be explained as my bottom cat guard shaking and hitting another piece of metal...

I also noticed (when a car was behind me and his lights were shining) that when I "floored it", there was a bit of smoke coming out of my exhasut...

No warnings from the car: No CEL, no high temp, no low gas (Though I did put in Arco this time X-[ ), no low oil pressure... no red lights, etc.

Anyone have any ideas? Car ran amazingly well a few hours ago...

I turned it off when I got home, killed the power to the car... hoping a nights rest and a "reflashed" ecu will fix it....
 

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If it sounds like some metal piece is loose, put the car on the jack stand and dip under. From your description, I'd go thru the exhaust, ensure every bolt/nut is tight, and check for cracks with some lights. Lightly knock on the exhaust pipe and it should sound crisp, but will be dull near the crack. Yank the pipes a little, some times look can be deceiving.

You may want to check header and down pipe, and especially where header meats down pipes...

and don't limit yourself with exhaust pipes, check for any possible loose items while at it.

good luck
 

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Make sure ...

that is you changed the x-pipe that you put the gaskets in there and it's tight.. If not it will cause the cat's to over heat and burn out..... From there it can get worse...
 

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...

Sounds to me like your cat might be burnt out. Get under the car and bang on the exhaust a little to see if you can find the noise.

Just FYI If you go to Fabspeed.com and look at their Maserati exhaust explanation video you can see what a burnt out catalytic converter looks like.
 

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I agree. Sounds like a broken up CAT. That would change the exhaust note, make the metallic noises and cause a little smoke. I don't know if you recall but both of my CATs broke up and were replaced under warranty. The CEL should come on soon. BTW... Do you smell "rotten eggs"? A sure sign!
 

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Discussion Starter · #8 ·
Ok guys...

So I put the car on a lift today, turned it on and the noise was coming directly from the precat (the one attached to the passenger side manifold)...

Cat is dead.

I decided to drive over to my mechanic and get it checked out as the only "bad signs" I had were sounds, a bit of smoke, and a change in the exhaust note.

Halfway there, the CEL started to flash, car lost what felt like 400 HP, and it wouldnt go faster than about 20 MPH. Got it towed.

Showed up there: Dead Cat. No doubt about it. Getting the cats "fixed" tomorrow morning :-D

The CEL showed misfirings on the passenger bank of the engine block BTW.

-Ali

PS: GrndLkNav; Gaskets? It didnt come with any gaskets...
 

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There should be some kind of gasket

between the pipe and the cats as well as the cats and the headers. It seals the system, otherwise you end up with burnt cats and on the header side you end up with burnt exhaust valves. We used to start the engine, let the exhaust start getting hot then spray paint down the exhaust pipe till it quit burning and that's were we would cut it off and run it straight out the side of the car... That's the point where the exhaust valve wouldn't be damaged.... Anyway, old chevy drag racing stuff there....
 

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Caused by Mods?

Ok guys...

Showed up there: Dead Cat. No doubt about it. Getting the cats "fixed" tomorrow morning :-D

The CEL showed misfirings on the passenger bank of the engine block BTW.
Hi,

My recollection is that you have done a number of Mods above and beyond the exhaust. I know there have been some discussion regarding risk to Cat from some of these enhancements. Do you think this is an issue with your car? If so, it would certainly make me reconsider moding my car. Good luck with the repairs, please keep us posted.
 

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I don't know if you recall but both of my CATs broke up and were replaced under warranty. The CEL should come on soon. BTW... Do you smell "rotten eggs"? A sure sign!
Good call, I recall that smell on our little Sunday drive a few weeks ago. Out of eleven cars, couldn't tell which one it was, but there was the occassional whiffs of sulfur. Quite noticeable with the top down.

Wrt your cats, I thought only one pre-cat was broken up? Turned out it was both?
 

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Discussion Starter · #12 ·
Hi,

My recollection is that you have done a number of Mods above and beyond the exhaust. I know there have been some discussion regarding risk to Cat from some of these enhancements. Do you think this is an issue with your car? If so, it would certainly make me reconsider moding my car. Good luck with the repairs, please keep us posted.
Nope, Not the mods. I hit a really bad pothole: The cat has a "dent" in it about 1 inch in and 1.5 inches wide... Also, the guard on that side oof the cat has been smashed...
 
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