harshly resonant exhaust system

[BubbaMO]

I have a 2005 LS, V8. I recently had a CEL that signaled a failed catalytic converter. Local Ford dealer attempted to replace the entire catalytic converter assembly, both left and right and associated tubes. They tried two different Magnaflow assemblies. Problems with angle of converter body and/or flange mating. The third was Walker, I think. They gave up when the third assembly wouldn't fit and sent it out to a muffler shop that could bend pipe.

The exhaust moans and buzzes at various rpm's... even a slight howl. Any advice on how to get back to a smooth growl?

 

[joegr]

Stock exhaust from junkyard?

 

[BubbaMO]

Stock exhaust from junkyard?

I take it that means the changed sound is unavoidable with aftermarket parts?

 

[joegr]

I take it that means the changed sound is unavoidable with aftermarket parts?

I don't know that to be true, just likely.

 

[BubbaMO]

I don't know that to be true, just likely.

I suspected it might not be something I can "fix", and at least a consequence of different parts/flow/configuration. Thanks!

 

[jerryg2112]

Did you look for clearance? Pipes make a lot of noise if they contact the frame or any other components.

 

[BubbaMO]

Did you look for clearance? Pipes make a lot of noise if they contact the frame or any other components.

I'm going to take it back to the dealer and see if they'll check for that. Thanks!

 

[AmsterDutch]

I'm going to take it back to the dealer and see if they'll check for that. Thanks!

I'm not sure what's exactly going on with your exhaust but I've heard ppl who have used Magnaflow and it worked great ...are you sure you have the right part number? I'm not insulting your intelligence by any means but I find it strange that ppl have installed Magnaflow exhaust systems themselves on the backs without a lift and successfully experienced a brand new exhaust

 

[BubbaMO]

I'm not sure what's exactly going on with your exhaust but I've heard ppl who have used Magnaflow and it worked great ...are you sure you have the right part number? I'm not insulting your intelligence by any means but I find it strange that ppl have installed Magnaflow exhaust systems themselves on the backs without a lift and successfully experienced a brand new exhaust

No worries, my intelligence isn't easily insulted. The dealer ordered the parts and tried to do the work. I drove it again this evening and it vibrates a lot at 20, 30 and 50 mph... and at startup. If I hover at the right rpm it'll vibrate continuously. I'm going to seek a fix/correction from the small town Ford dealer who farmed it out to a muffler shop.

 

[BubbaMO]

I picked the LS up this afternoon and it's fixed. The exhaust was up against the frame. They adjusted it and it's now back to near normal. A little louder than stock, but not much. Amazing how many sounds came from having the exhaust in contact with the frame. Thank you for your help, joegr, jerryg2112 and AmsterDutch!