I have close to 20,000 kms on my 2012 991S with factory PSE. Recently, with PSE on only, I have started having a new vibration(sound) from exhaust during a limited rpm range when accelerating hard between 50-100km/hr. Sound is like tiny particles are flying and hitting pipe walls. I can reproduce the sound with very hard acceleration not just hard acceleration. Sound is not continuous just appears for a limited range and then goes away. I consider this abnormal as it was not there before and doesn't sound quite right.

I do plan on getting this checked by dealer, but any heads up on what this likely is? And what the fix for it is ?

 

My Boxter RS-60 PSE did that- a transient fluttering of the bypass valves when they open (eg get to the rpm where the vacuum opens them) was the consensus explanation on the net and at the dealership. Dealer declared it normal. My cure was to find a tunnel to reinforce my decision to have PSE.

 

I too have an odd sound from the pse. It sounds like a sympathetic vibration but it occurs at idle or low rpm it's transient and passes as the car accelerates. Any thoughts?

 

How kind of you to respond. How's that Yugo working out for you?

 

Happy New Year to you too...

 

Troll posts may have a similarly annoying sound and carry about as much meaning as the flutter.

 

This might be hard for you to believe but some people that can afford 100K plus sports cars like their sports car's exhaust to sound like an exhaust 100% of the time instead of a synthesized soundtrack when they hit the gas pedal and nothing the rest of the time...

 

Obviously, after spending a considerable amount of money for a new car, the OP was looking for help from this community. Posting irrelevant junk is both tactless and a waste of bandwidth. If you don't have anything productive to contribute, I suggest you go somewhere else.

As to the unusual sounds ... all I can say is most definitely tell the dealer and get it logged into your car's history. Even Porsches are not always perfect, and folks need to let them know so that if it does become an issue, surely they will fix it.

 

Oh ... and if you do get an answer, please share. We have members in our local PCA that just bought a Boxster S and another a 991 S. Thanks.

 

Again

My Boxter RS-60 PSE did that- a transient fluttering of the bypass valves when they open (eg get to the rpm where the vacuum opens them) was the consensus explanation on the net and at the dealership. Dealer declared it normal. My cure was to find a tunnel to reinforce my decision to have PSE

 

Thanks Chuck, times two. I noted your response earlier as one of our members just got their 981 a couple of weeks ago. If they ask, now I will have an answer. In fact, if you don't mind, I would like to use bits and pieces from this thread (no names, of course) in our newsletter.

 

Thanks for the response. I had it checked at dealer today and after a test drive with a tech his conclusion was that the butterfly sound is normal and related to the flaps opening under full load and nothing could be done about it. According to him this sound did not occur when the car was new because the valves was all tight and waxed at that stage. If it got considerably worse they would change the exhaust while under warranty. I guess I can live with it if it is normal and doesn't get any worse.

 

What flaps opening under full load are you talking about? I thought the PSE was either on or off, based on the switch setting on the interior console, at least that it the way it is on my 997 GTS. Maybe the PSE operates differently on the 991.

 

It is either on or off but the action is regulated by rpm mappings as well as the botton. In both your 997 and the 991 and every other model with PSE, to get from one state to the other the button operates a solenoid that moves a little flat flapper valve that routes the exhaust appropriately.

 

Well from what was explained to me, with pse on, depending on how hard you accelerate there is some valve/flap/membrane(whichever terminology u prefer) that further opens as required but not always. That creates the fluttering sound. No idea if the 997 gts is similar.