Funny Exhaust Note
 

I need the experts for this one:

I have noticed that the last few times I have taken my car out, a funny sound is comming from the exhaust or the rear-end, but it may even be originating from under the hood.

During WOT, as the rpms pass 4,000, is when I hear the sound. Almost sounds like a rumble. As the rpms go higher, it goes away. It is not real loud, just different and not the way it used to sound.

I have made NO changes to the exhaust and I feel no loss of power. I suspect perhaps something loose on the exhaust system, but it is not a metal on metal sound.

Here's another thing, when sitting in the driveway with no load on the engine, the noise can not be duplicated. But, as the rpms drop down, I can hear a slight crackle...almost like straight pipes but not nearly as noticeable. I don't know if this is related to the rumble or just me hearing something that was always there before...just never noticed.

I suppose too that the rumble described above could also be comming from the rear-end and not the exhaust...perhaps even the limited slip kicking in.

Any ideas?

Need a little more than that. Could be many things. Though, it sounds like an exhaust leak....Rumble at certian RPM, Crackle at low idle.

Any kind of vibrations or anything like such?

You cant hear a limited slip rear end at work. A locker...yes...limited slip...nope.

like funny ha ha ,like a clown, like it amuses you?

No, not quite that funny.

I took the car to a dealer today. The service manager is a Mutang enthusisit too....has had lots of them. His first impression of my exhaust was that I had some after market work done on it due to the slightly different sound. But, it is all stock. He believes the sound is from a bad muffler baffle.

I could care less as it is comming off anyway. Just glad that it did not sound serious.

Hi, im new to this site, but i have a large back ground in exhaust. to me it sounds like what you are hearing is exhaust resinance. my 03' Mach does the same thing, it also became a little louder when I installed my Dr. Gas x over, do to more exhaust flow. its just those cheesy ford mufflers. Im switching my cat back to Borla stingers, and I will let you know if it goes away.
By the way the Dr. gas x pipe is awesome!!!!!!!!!