As of this morning, when accelerating there is a loud hissing noise and loss of power.

I know my cat is worn out, because there is rattling noise coming from it, and the car jerks a little when driving, and I have poor gas milage. I plan on replacing that here soon.

Another weird thing is, when I sit in park and rev the engine, the rpm stick wont go pass 4-5k anf it bottoms out/makes a boggling sound. Sounds like crap.

And also the engine/exhaust is quiet at idle and doesnt have the sound it use to.

Is all of that cause of the cat? Even the hissing? I heard vaccum leak, but how do you test that?

Thanks.

 

Its a 97 base model v6 3.8L automatic

 

sounds to me like a vacuum leak.

best bet is to get some starting fluid and start spraying all of the rubber lines in the engine bay. Listen carefully for a jump in idle, if it does, you've found your leak

 

Yep, your cat is clogged/broken apart inside, which is restricting your exhaust flow, and the engine's performance. The hissing is your exhaust trying to get out anywhere it can, most likely at the headpipe to manifold donut connection, and/or at the flange before the cat (if yours has one). Take a look at your cat after driving the car a bit, I'll bet it's glowing red hot.

 

Ok, I sprayed starter fluid, didnt hear a change in idle. I followed the exhaust clear back and there is a soft constant squeal that sounds like its coming from the rear exhaust. Which I just found out it has a magnaflow exhaust on it and I didnt know. I feel like an idiot telling ppl its stock when they asked.

I guess that cancels out replacing the whole cat back with magnaflow exhaust. I planned on getting a magnaflow cat anyways. Unless my whole exhaust needs replaced anyway.

 

thats good to hear. You wouldnt believe how many times I have to get gas. Its getting ridiculous. Im gonna replace it once I get paid next week. Think it'll be ok to drive until then?

 

You're not doing the engine any favors driving it like that, I'd keep trips down to a minimum. Since you know the cat is trashed, you could always drill some relief holes on the bottom side of it, close to the front. She'll be a little noisy, but that beats the alternative.

 

I drilled 2 holes for now. I didn't want to make more and have it sound real bad. Hopefully that will do justice until next week or so.

Thanks everyone for the replies.