Big Exhaust Problem

[Aquarius]

Hey Guys,

I have an 03 GT and I think I may have a pretty serious problem with my exhaust. About a month ago I replaced my BBK H-pipe with a BBK X-pipe because I had heard a rattling in the exhaust. Turns out one of the cats had melted down and fell apart and the pieces were knocking around between the cats and cat-back. I managed to pull two tennis ball-sized pieces of cat honeycomb out of the front of the cat-back. So I've been running with the next X-pipe for a while now, no problems and two weeks ago I heard a similar rattle. Sounds like a screwdriver bouncing around in the exhaust and it gets worse as I lay on the accelerator because the exhaust flow speeds up. I don't know where the rattling would come from now though, its a new X-pipe - there's now way those cats could have already broken down. Or is there?


Over the weekend the noise seemed to go away.....now I fear I have a bigger problem. The exhaust has quieted down significantly and when i get the RPM's up around 3000 for any length of time the car starts to shake very uncharacteristically. If I had to guess, one side of the exhaust is clogged. To complicate things, I have the Flowmaster 40 cat-back, what if parts of the broken up cats are lodged in the delta-flow channels? Am I pretty much screwed? Any suggestions?

 

[RedDaemon]

the rattling could be the heat shields on the cats. take them off or give them a whack to see if theyre loose. you can also tap the cats to see if there is anything lose in them as well

 

[snidehockey]

I don't know how to explain it getting quieter, but I had alot of rattling before I found that on of the flanges that connected my headers to the BBK H was kinda loose.



Other than that, if your cat is clogged it will get like red hot, literally. Take a look under the car while it's on.

 

[nyuk98gt]

Aquarius:

Maybe pieces of the catalyst have travelled into the muffler(s)? If a heat shield is loose, you can put a big hose clamp on it but don't crank it down too hard or you will crush the shield (there should be a small gap between the converter and the shield).

Please post back with an update ("enquiring minds want to know").

Chris

 

[Aquarius]

If pieces made it into the muffler what are the chances that they're going to make it out? Those Delta flow channels don't make for an easy path out of the mufflers.

 

[BobHyatt]

Hey Guys,

I have an 03 GT and I think I may have a pretty serious problem with my exhaust. About a month ago I replaced my BBK H-pipe with a BBK X-pipe because I had heard a rattling in the exhaust. Turns out one of the cats had melted down and fell apart and the pieces were knocking around between the cats and cat-back. I managed to pull two tennis ball-sized pieces of cat honeycomb out of the front of the cat-back. So I've been running with the next X-pipe for a while now, no problems and two weeks ago I heard a similar rattle. Sounds like a screwdriver bouncing around in the exhaust and it gets worse as I lay on the accelerator because the exhaust flow speeds up. I don't know where the rattling would come from now though, its a new X-pipe - there's now way those cats could have already broken down. Or is there?


Over the weekend the noise seemed to go away.....now I fear I have a bigger problem. The exhaust has quieted down significantly and when i get the RPM's up around 3000 for any length of time the car starts to shake very uncharacteristically. If I had to guess, one side of the exhaust is clogged. To complicate things, I have the Flowmaster 40 cat-back, what if parts of the broken up cats are lodged in the delta-flow channels? Am I pretty much screwed? Any suggestions?

If you "tune" the car, and get the A/F too rich, it will smoke the cats. If you run odd crap thru the motor frequently (sea foam, etc), it will smoke the cats. Best bet is to get rid of 'em. You can even burn exhaust valves if you are not careful when they get clogged.

 

[Aquarius]

Dropped the car of to the shop last night. There is a significant difference in pressure between the two tail pipes so I imagine the one on the right is clogged - most likely with pieces of catalytic honeycomb.

Now here's my question: The mechanic wants me to take off the long tubes, says they're more trouble than they are worth (which he's partially right because I've been getting ETC codes for the last year with them. Personally, I like them on there, they sound good and get me about 15 more HP on the dyno. My biggest concern is how I've gone through a second catted x-pipe in just over a month. Is this due to the long tubes? Maybe too much flow? A bunch of you have suggested going catless but I need them for emissions up in RI (somehow the car passed with long tubes but that's another story). The mechanic was saying I should go with some JBA or Ford Motorsport headers in their place. I'd consider it if money grew on trees but I'm one of the broke college kids with not too much to spare. What's everyone elses opinion?

 

[RedDaemon]

listen to BobHyatt. he is correct.

if your car is running TOO RICH it will destroy the cats as well as you running any foreign/exotic crap through the engine (SEAFOAM) frequently.

in short. get the cats replaced and get your car tuned so its not running as rich. this will solve your problems. there is no need to take the headers off. he just wants to do more work to make some $$$. there are countless of people on here with headers and cats (well maybe not as manay as headers and no cats ) that dont have a problem when it comes problems with their cat. converters.

have him replace the midpipe and tell him to shut his mouth


i highly recommend getting it tuned however if you chose to go that route or else youll run into the same problem

 

[Aquarius]

Is it a problem with the BBK headers and cats? I just want to fix the problem and be done with it. If going with Bassani headers and catted x will fix the problem then I'll do it but I don't want to go through any more exhaust hassles like this.

 

[SaleenGT2001]

the headers ARE NOT the problem. you should look at your tune and see what the AF is.i bet it is rich as hell and causing all your problems

 

[Killa]

no cat FTMFW !!!

 

[TyMx926]

i have the exact same problems, my exhaust leaks by my passenger side horribly but i cant get the gaskets from the the headers to the mid pipe to stay in place putting the pipes together so i took them out (horrible idea) but before this my cats blew out and my magnapacks rattle, is this the honeycomb that could be built up in them still and clogging them? i replaced the stock x with a pypes not catted and it helped for awhile but now its running horrible and sounds worse! i can't have a shop fix it now w/o cats.....what to do, what to do??