I have a 1996 Jeep Cherokee Sport. I recently had it looked at by a mechanic and he was able to fix the exhaust, the brakes, refill the fluids, and look at the check engine light. Everything had been going fine until I started the car tonight and the engine seemed way louder than usual. It didn't just get louder, though, it seemed to have to work a lot harder to get up to speed and stuff. Finally, when I parked, I decided to rev the engine to see if I could hear anything weird, and I ended up hearing the engine rev up, but then it sounded like only air was running through there and it sounded like it was about to die on me. Please help, I need this for my job.

 

What was wrong with your exhaust that he "fixed"? What you're describing sounds like a cracked header (very common with Cherokees) or like some part of your exhaust system has fallen off. Also very common with Cherokees... things fall off of mine all the time.

Where, specifically is the noise coming from?

 

The exhaust had a hole in it so I had to get that patched up. It was running smoothly up until yesterday so I don't know what's wrong with it.
A majority of the noise is from under the hood, I haven't taken a close enough look at it to know exactly where it's from in there.

 

Also, if it makes any difference, the header is brand new.

 

Did you replace the header or did you have it replaced? As I said, the sound you're describing could be an exhaust leak. With all the work that's been done on your exhaust, it's possible that a bolt got missed or something go knocked loose. You're gonna have to lift the hood and locate the source (general location) of the sound in order for us to help. There are obviously a lot of components involved and without more info, we're just taking a shot in the dark.

 

check for a plugged cat symptoms: power loss, glowing thing under the vehicle, sounds like your engines loading up as you speed up or rev the engine, blown exhaust gasket(s), lots of heat as you walk by the cat on the pass. side, little exhaust pressure at tailpipe,holes in exhaust pipe before cat