Since I put in headers in my car, i have been hearing what sound like a leak. It sounds like a hissing noise with a tick to it (or a ticking hissing noise, if you can understand that). I have gone back and made sure all the bolts are tight, i have tried to feel around to see where the leak is, and nothing. I have also tried looking at the gaskets trying to find dark spots, which would supposedly indicate where the leak is, and there are none.

If I had to guess where it is leaking, i'd say it was at the transition between the y pipe and cat, as they are not welded, it is on with a clamp and the sound seems to be slightly louder in this area.

Why am I talking about an exhaust leak when my post says something about a clogged cat? Hold on, i'm almost there.

I was reading an article in chevy hi performance where they mentioned a clogged cat that would keep the motor from turning over 2000 rpm, and i thought of something. My car feels kinda sluggish compared to how it did about a year ago even though i've added headers since then. It won't rev past 3000 sometimes. The car is in good mechanical condition and the check engine light has never come on, so in theory, all the sensors are functioning properly, right?

So here is my question- would it be possible for a clogged cat to cause enough resistance in the tailpipe to cause a leak between the cat and y pipe, and could it make that big of a difference performance wise?

How can i tell if it is clogged or not? The car has the stock cat

 

Sorry, I didn't notice how lond this post was when I wrote it.

 

just get rid of it and weld a straight pipe in its place.. if you can.. if not i would get a new one..

 

It makes a hell of a difference! Get a new hi-flo cat or run a pipe through it. You will definitely feel it.

 

To answer your question will a clocged cat make a car run sluggish, yes it will. I had this problem with my TransAm and it got to the point where it litteraly took me a minute to get up to 30 mph.

 

i had one just this past weekend. had no pull whatsoever above 3K RPM, and made a horrible hissing noise when i accelerated. put in a 3" catco cat, and LOVE IT! lot better sound, and a little better performance. that and ram air off a TPI shaved .3 off my 1/8 time.

 

Well, you say that you notice this sluggish performance only some of the time so that slightly lowers the chances that a clogged cat is the culprit. Usually a clogged cat will make it choke off all of the time.... It is still quite possible that the converter is causing it, but hard to say over the internet without hearing it and all.....

Either way, a high flow cat (or better yet - a test pipe) will yield more power and likely seal better at that junction with the Y-pipe.

I would slap a test pipe in there... And you may not have to have it welded in. I have had really great results from using those stainless steel band clamps with slip fit joints. They really cover up the joint and form fit to it nicely. Plus they don't crimp the pipes which makes future dissassembly much easier and they don't hang down any further than the pipe itseld - conserving ground clearance .

Laterzzzzzzz,
Matt

 

Thanks for your help guys. The sluggish performance is there like 90% of the time, and every once in a while in runs pretty nice. I don't know what the deal is with that. The noise I was talking about though is always there. I'm definitely gonna try to either get the catalytic replaced, or just put in a straight pipe. What do you guys think would be a better idea? We don't have any emissions testing in Miami, but I think there is a 2500 fine for not having a catalytic. No one ever checks for a catalytic though, so thats not a big deal.
The major reason that I'm indecisive over which would be better is because I'm gonna put in a carbed 350 later on, and I won't have an air pump at all. I guess I'm gonna go with whatever will work best with the 350. Since its not gonna have an air pump, I'm guessing it would be better, and cheaper to have a straight pipe.
Let me know what you guys think.

 

I'm running my cat (stock replacement, not hi-flo ) with the AIR tube capped off.