Heat-shield like sound at low rpm
06-27-2020, 06:58 AM
#46
Took mine in for service and the dealer confirmed they can hear it. We then reproduced it on another c2s off the lot but it was more muted. The dealer claimed it might be exhaust or turbo sounds and offered to keep the car and attempt to disassemble in an exploratory search. Given that it was also present on the other car I decided to keep my car intact and deal with it for now and hope that Porsche finds and issues a recall. For now I will just consider this a slightly annoying part of the 992 character like the HomeLink interface.
For me it is definitely not an intrinsic turbo or exhaust sound (ie not something rattling within a component). What I do think is that at a particular engine speed, some component is vibrating, and that it comes into contact with a heat shield or something similar (eg an exhaust pipe against a heat shield or a gear box against part of the chassis). I feel strongly that it is a ‘contact’ rattle.
06-27-2020, 09:42 AM
#47
Rennlist Member
For me it is definitely not an intrinsic turbo or exhaust sound (ie not something rattling within a component). What I do think is that at a particular engine speed, some component is vibrating, and that it comes into contact with a heat shield or something similar (eg an exhaust pipe against a heat shield or a gear box against part of the chassis). I feel strongly that it is a ‘contact’ rattle.
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JHesketh (06-27-2020)
06-27-2020, 03:46 PM
#48
I agree a contact rattle is a possibility, but I also think it's possible it's a resonant noise from a panel or heat shield. I have noticed that the noise seems more muted if I have a passenger. Can't figure out that one, but it makes it more difficult to demo. I hope to do my own look see late next week.
09-12-2020, 04:37 AM
#49
Short update:
(1) Dealer finally reproduced the sound 🙌.
For me, it is dependable once the car is warm. Slow down so revs drop just below 1400, lightly accelerate to keep car rolling, and voila, a resonance that turns into a rattle.
(2) Dealer‘s loaner 992 C2S suffers the same ‘feature’ but the sound is not as pronounced and the rev threshold is not quite the same.
(3) Engineer thinks that’s this is a flywheel balancing problem. They are in consultation with Stuttgart. I will update here as things develop.
(1) Dealer finally reproduced the sound 🙌.
For me, it is dependable once the car is warm. Slow down so revs drop just below 1400, lightly accelerate to keep car rolling, and voila, a resonance that turns into a rattle.
(2) Dealer‘s loaner 992 C2S suffers the same ‘feature’ but the sound is not as pronounced and the rev threshold is not quite the same.
(3) Engineer thinks that’s this is a flywheel balancing problem. They are in consultation with Stuttgart. I will update here as things develop.
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rouxeny (09-12-2020)
09-12-2020, 05:30 AM
#50
Short update:
(1) Dealer finally reproduced the sound 🙌.
For me, it is dependable once the car is warm. Slow down so revs drop just below 1400, lightly accelerate to keep car rolling, and voila, a resonance that turns into a rattle.
(2) Dealer‘s loaner 992 C2S suffers the same ‘feature’ but the sound is not as pronounced and the rev threshold is not quite the same.
(3) Engineer thinks that’s this is a flywheel balancing problem. They are in consultation with Stuttgart. I will update here as things develop.
(1) Dealer finally reproduced the sound 🙌.
For me, it is dependable once the car is warm. Slow down so revs drop just below 1400, lightly accelerate to keep car rolling, and voila, a resonance that turns into a rattle.
(2) Dealer‘s loaner 992 C2S suffers the same ‘feature’ but the sound is not as pronounced and the rev threshold is not quite the same.
(3) Engineer thinks that’s this is a flywheel balancing problem. They are in consultation with Stuttgart. I will update here as things develop.
Good luck! Hope it gets sorted out for you.
09-12-2020, 07:14 AM
#51
Rennlist Member
Thread Starter
Short update:
(1) Dealer finally reproduced the sound 🙌.
For me, it is dependable once the car is warm. Slow down so revs drop just below 1400, lightly accelerate to keep car rolling, and voila, a resonance that turns into a rattle.
(2) Dealer‘s loaner 992 C2S suffers the same ‘feature’ but the sound is not as pronounced and the rev threshold is not quite the same.
(3) Engineer thinks that’s this is a flywheel balancing problem. They are in consultation with Stuttgart. I will update here as things develop.
(1) Dealer finally reproduced the sound 🙌.
For me, it is dependable once the car is warm. Slow down so revs drop just below 1400, lightly accelerate to keep car rolling, and voila, a resonance that turns into a rattle.
(2) Dealer‘s loaner 992 C2S suffers the same ‘feature’ but the sound is not as pronounced and the rev threshold is not quite the same.
(3) Engineer thinks that’s this is a flywheel balancing problem. They are in consultation with Stuttgart. I will update here as things develop.
09-12-2020, 10:35 AM
#52
Rennlist Member
Yes, please keep us updated. I could not get my dealer interested in pursuing it. Even the zone rep would not even look at the car even though I demonstrated the issue to both the sales folks and the service tech. My own inspection using my own lift didn't turn up anything likely loose and rattling.
09-12-2020, 01:41 PM
#53
I know the sound, but not from 911s.
BMW, similar rpm on a 2012 M3. Only happens on the throttle, sound about right (this was 8 years ago, bear with me).
long story short, when the exhaust was warm and the metal expanded slightly, the baffles in the exhaust would vibrate under exhaust flow. Not cold, only when warmed up. Two replacement back boxes later, resolved!
My money is on something very similar, it needs a rolling road and sensor to pick up imo.
BMW, similar rpm on a 2012 M3. Only happens on the throttle, sound about right (this was 8 years ago, bear with me).
long story short, when the exhaust was warm and the metal expanded slightly, the baffles in the exhaust would vibrate under exhaust flow. Not cold, only when warmed up. Two replacement back boxes later, resolved!
My money is on something very similar, it needs a rolling road and sensor to pick up imo.
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JHesketh (09-13-2020)
09-12-2020, 02:49 PM
#54
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OK, so I have the same thing in my now-two-month-old C2S. Clear rattle at very low revs with reasonable throttle, and that chirping sound on light throttle across lower rev ranges. The chirping is most audible when passing through enclosed spaces like a parking garage. I've been debating whether to get it looked at but will call my dealer Monday to book it in.
09-13-2020, 06:54 PM
#55
I know the sound, but not from 911s.
BMW, similar rpm on a 2012 M3. Only happens on the throttle, sound about right (this was 8 years ago, bear with me).
long story short, when the exhaust was warm and the metal expanded slightly, the baffles in the exhaust would vibrate under exhaust flow. Not cold, only when warmed up. Two replacement back boxes later, resolved!
My money is on something very similar, it needs a rolling road and sensor to pick up imo.
BMW, similar rpm on a 2012 M3. Only happens on the throttle, sound about right (this was 8 years ago, bear with me).
long story short, when the exhaust was warm and the metal expanded slightly, the baffles in the exhaust would vibrate under exhaust flow. Not cold, only when warmed up. Two replacement back boxes later, resolved!
My money is on something very similar, it needs a rolling road and sensor to pick up imo.
i will keep posting any progress here.
09-15-2020, 08:52 PM
#56
Rennlist Member
Met with my dealer's general sales mngr today and wheels now seem to be in motion for the regional guy to meet with me and the local technician so I can demonstrate the problem to him. Sales mngr rode with me today and heard what I am talking about. Will report back, probably in 3 or 4 weeks.
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JHesketh (09-16-2020)
09-16-2020, 07:45 PM
#57
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09-17-2020, 09:53 AM
#58
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C4S, have had the same noise since the start when I got it earlier this year. I would have characterized it as a tin can with the lid partly opened and rattling just a little. The dealer tech took it out, acknowledged the sound, and said that all 991's seem to make that noise (not limited to the 992, at least based on what this tech said). It doesn't bother me tremendously, so just live with it - but would be great to have it sorted.
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JHesketh (09-17-2020)
09-17-2020, 10:00 AM
#59
The 911 Heritage Squeak Package is a no cost option
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09-17-2020, 10:13 AM
#60
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