Looking For Suggestions For Two Things... - BMW Forum

jetblack · 05-29-2005, 11:28 PM

I have this really annoying rattle sound from under the car. It is driving me nuts. I am embarrassed to drive the bimmer right now. So, yesterday, I got underneath to have a look. I was hoping it would be my exhaust heat shield, and I was gonna just rip the damn thing off. I found that every flange and bolt on my exhaust from the end of the cats to the tips of the muffler are rusted out. Not just a little bit, they are now just nubs, unrecognizable as bolts.

Soo, I'm thinking with 140K on this thing, it's probably time for replacement of everything from the manifold back.

Where is the cheapest place to buy a new cat section? Has anyone tried any of these ebay ones that are only about $300?

Also, I want performance, but I hate loud exhaust. I'm almost positive the UUC will be too loud. What is the quietest cat back system, or should I just remain with stock or maybe M3?

P.S. I didn't find the rattle after all that. Could it be something with the brakes?

dutchbmw · 05-30-2005, 09:16 AM

There's a shield over the O2 sensor part. It keeps the sensor on its working temperature. I ripped it off from my previous car cuz it was getting on my nerves.

You can't really increase the performance curve by only changing the last part of the exhaust system. I've seen graphics of a dyno before and after an aftermarket muffler. IMO it's only for a better look and a sportier sound.

Make sure to get a good working cat, because it's a part of the engine management system. When it is going bad the O2 sensor will send a signal to the ECU. The engine goes at the distress setting then which means a higher fuel consumption and a less smooth running engine.

jetblack · 05-30-2005, 01:05 PM

Thanks. My car isn't running very smooth, even after new plugs. I am hoping the new exhaust will fix it. So, anyone have a suggestion for somewhere to pick up the catalytic converter?

ldsbeaker · 05-30-2005, 04:33 PM

I've asked this same question numerous times here, and haven't gotten any responses. I'm about ready to get a CATCO Universal Cat from Ebay, and see if it works. If I remember correctly, they are about $40. Keep us informed.