ok i have been trying to search for three hours but i give up. I have a damn noise that started a few days ago and i can't figure out what is making it. Ok so it is like a rattling or scraping noise, more like scraping but I am hoping it might be a rattling noise. It only makes it at a certain rpm (~2000RPM) and it sounds like it comes from underneath the car. It does not matter what gear it is in (M6) nor does it matter if i am speeding up or slowing down. Also it makes it no matter if the clutch pedal is pressed or not. I tried laying down by my car with the door open and pressing the gas pedal to hear it. sounds like it may be coming from the catalytic converter, but it doesn't sound like a certain one (i had my gf step on the gas (in neutral)and I listened from the passenger side. From all of that it may be coming from either cat or both or the transmission... I have no idea. I'm leaning towards the cats mainly because i bought the MAC mids and catted y pipe used from some dude and he said they were installed when he chunked a piston. So i figure oil, or a chunk of the piston could have gotten to them... argh anyways it is annoying the hell out of me and i need some other people's opinions.

Thanks,
Dave

 

Could be the cats... I hope you know that the MAC cats really suck. I'd chuck them for some Car-Sound cats.

The rattling could be a heat shield for the exhaust. Maybe get the car on jacks and blocks and get under a little bit and have someone hold the gas while you press down on the heat sheilds to see if the rattling goes away... Just a though.

 

Yeah i know, MAC cats really suck. Thanks for the suggestion on the heat shields I'll try that today, just gotta find some thick gloves. I'm trying to decide now whether to replace the cats or just go without...

Dave