I have noticed this strange exhaust noise / rattle for the past few months. Just got the car back from mechanic in Lake Forest (Hergeshemier) for the 60k service and they could not find anything.
It's very noticable when driving cold and also even more noticable when driving close to buildings/homes. It sounds like I have a exhaust leak. Sometimes like a harley davidson kind of sound.
I tried rubber hammering the cats with engine cold to hear any loose sound, but nothing.
Is it time for dealership?
Has anyone heard this symptom before? Do PSE's go bad?
Open for suggestions.

 

Could be a baffle inside the muffler coming lose.

 

i dont know if its the same rattle, but i have a 996 2001 with twin exhausts and apperently there is a flap inside each pipe that is active when the engine is cold and it does rattle audably but when the engine is warmed up the flaps stop opperating and the rattle stops, this is all quite normal

 

I kinna like that rattle....

 

I'd agree with the above comments; likely the baffles in the PSE.

Have you tried disengaging the PSE baffles? Meaning if your system has active baffles, (quiet between 25-40 mph) rather than wide open loud all the time.

Try this link:
http://www.renntech.org/forums/index.php?showtopic=2470

 

I don't have a switch to override the baffles. Is it something that could be removed by dealer? Mine was apparently set to wide open since i don't have the wiring to the front of the car.
Please tell me why baffles have gone bad after 30k? how easy is it to fix this baffle issue?

 

The default on the PSE is open/loud. It takes vacuum lines, a change over valve and switches to have an "active" PSE (by the way there is a setup for this for sale right now by an owner on Rennlist). If ou don't have the system to switch over the PSE than by default it is always open/loud.

Baffles coming loose in the 996 mufflers, either stock or PSE, is not uncommon.

 

Hey,


some guys here in germany open their PSE and then they make some welding points inside the muffler...after that no more noise in those mufflers !!

Greetz....

 

This is strange. This week I made an appointment to take the car to dealer. (I have extended warranty). But today I noticed the noise is gone. ???
Did the baffle come loose and exit through the exhaust? Or is it stuck in a position now that doesn't make the noise?
I am puzzled.

 

2004 996 4s. problem was cats. had both replaced under warranty. 24k miles.

 

Update:I replaced the driver side PSE muffler with factory exhaust that I had in storage and the noise/rattle is gone.
I did some research and found out that Darin at FDMotorsport has seen this problem with loose baffles. He asked me to send the exhaust to him so he can weld the part that comes loose. I hope to get it back soon, cause the stock muffler sound doesn't do justice.

 

I had the same issue at about 70K miles. My cats were replaced and the rattle stopped.

 

7k worth of mufflers these days, and they fail. Nice, Porsche.

 

Link pls ? couldn't' t find it

 

When I first saw the heading, I thought we were going to have to tell you that was your engine you were hearing for the first time.