[Fliz]

In my new 2018 BS with about 500 miles... Occasionally I notice what sounds like a sine wave around 150/300Hz from the engine area at idle. It can be constant or periodic - on every few seconds for a few seconds, over and over. I’ve heard it when the car is cold or after a drive so no correlation with that. Off idle it stops I think but then returns when back on idle. Or it's masked by other sounds.

I don’t have much experience with turbo cars or cars with “sound actuators” like ours have so not sure if this could be due to either of those. I suppose the engine (and car) itself has resonance frequencies but seems strange that it’s intermittent and sounds so tone-like.

Should also mention that the car drives wonderfully and I don't sense anything different performance wise when this happens.

Anybody else ever hear anything like that from their 718/S or have any ideas?

 

[trusted]

Interesting. I also do hear a "strange" oscillating sound occasionally shortly after startup. First I thought it comes from the speakers, but it isn't I think. I'm starting to suspect it has something to do with me activating PSE and Sport right after startup. Sound actuator is a possibility as well for sure. It doesn't happen frequently enough to really bother me and never when the car is warm so far. But after reading your post I'll keep watching if it becomes more frequent.

 

[Fliz]

Interesting. I also do hear a "strange" oscillating sound occasionally shortly after startup. First I thought it comes from the speakers, but it isn't I think. I'm starting to suspect it has something to do with me activating PSE and Sport right after startup. Sound actuator is a possibility as well for sure. It doesn't happen frequently enough to really bother me and never when the car is warm so far. But after reading your post I'll keep watching if it becomes more frequent.

Ah, ... maybe I'm not hallucinating after all.

It's also not really bothering me, more of a curiosity. Can't really bring it in to the dealer to ask as it's so intermittent.

BTW - I don't have PSE, though do tend to run in Sport a lot.

 

[johan]

Ah, ... maybe I'm not hallucinating after all.

It's also not really bothering me, more of a curiosity. Can't really bring it in to the dealer to ask as it's so intermittent.

BTW - I don't have PSE, though do tend to run in Sport a lot.

When your Sport mode the soundaktor is On for sure.
And think its always On in some way.

 

[ZuffenHouseRules]

In one of the many 718 articles and reviews I've read (sorry I don't have the link at hand), I very distinctly recall this point: Porsche engineered a Helmholtz resonator https://en.wikipedia.org/wiki/Helmholtz_resonance
as part of the new exhaust tubing. That would account for a tone at some select frequency (corresponding to a musical note I'd expect), although I've not been able to hear it myself.

 

[trusted]

In one of the many 718 articles and reviews I've read (sorry I don't have the link at hand), I very distinctly recall this point: Porsche engineered a Helmholtz resonator https://en.wikipedia.org/wiki/Helmholtz_resonance
as part of the new exhaust tubing. That would account for a tone at some select frequency (corresponding to a musical note I'd expect), although I've not been able to hear it myself.

Thanks for posting this. In my case I'm convinced that's it. The "tone" is only audible to me sometimes for a brief moment when the car comes out of startup mode.

 

[Fliz]

In one of the many 718 articles and reviews I've read (sorry I don't have the link at hand), I very distinctly recall this point: Porsche engineered a Helmholtz resonator https://en.wikipedia.org/wiki/Helmholtz_resonance
as part of the new exhaust tubing. That would account for a tone at some select frequency (corresponding to a musical note I'd expect), although I've not been able to hear it myself.

Ah.... that sounds like a definite suspect. I found this article...

https://newsroom.porsche.com/pdf/print/3f653a25-5500-4432-be92-192b326ae1df

It does actually remind me of the sound of blowing over the top of an empty bottle which is essentially a Helmholtz resonator.

Now I wonder why it would be intermittent and even periodic when sitting at idle... something must be changing the airflow across the opening of the resonator over time.

 

[johan]

Helmholtz on intake are quite common but have never seen it on an exhaust.
When i where looking at the soundaktor on the Tech pdf i also looked at the exhaust and the fact that one pipe is longer and that the mufflers aint the same.
But it did not say anything about one being a helmholtz.


Any ideas on how aftermarket exhausts are being designed?

 

[Alain44FR]

I heard the same noise at idle when I trailed a 718 CS brand new. I puted it on the sport mode to stop this.
However I just ordered a new 718 C GTS that Porsche ingénieurs will find a solution with the new turbo.
This car is so fantastic except this noise at idle.
I am happy too that somebody put that on the table.

 

[nineball]

Any ideas on how aftermarket exhausts are being designed?

i may have some input on this in a few weeks. during their sale i ordered a new exhaust from fabspeed, the turbo-back full system, and it only uses one pipe. i am hoping to have it arrive in the next week or so. i am going down to daytona raceway at the end of the month for a DE weekend and really want to have it installed by then.

 

[Fliz]

Any ideas on how aftermarket exhausts are being designed?

From the Fabspeed site regarding the Turbo back system for the 718:

Fabspeed's Supercup Turboback Exhaust System installed - we tested variants with and without resonators, ultimately deciding on a resonated version as it added refinement to the exhaust tone.

See: Porsche 718 Boxster / Cayman Supercup Turboback Exhaust System

 

[johan]

i may have some input on this in a few weeks. during their sale i ordered a new exhaust from fabspeed, the turbo-back full system, and it only uses one pipe. i am hoping to have it arrive in the next week or so. i am going down to daytona raceway at the end of the month for a DE weekend and really want to have it installed by then.

From the Fabspeed site regarding the Turbo back system for the 718:

Fabspeed's Supercup Turboback Exhaust System installed - we tested variants with and without resonators, ultimately deciding on a resonated version as it added refinement to the exhaust tone.

See: Porsche 718 Boxster / Cayman Supercup Turboback Exhaust System

Thanks guys

 

[Fliz]

i may have some input on this in a few weeks. during their sale i ordered a new exhaust from fabspeed, the turbo-back full system, and it only uses one pipe. i am hoping to have it arrive in the next week or so. i am going down to daytona raceway at the end of the month for a DE weekend and really want to have it installed by then.

I'll be really curious to hear (no pun intended) about this as well. The more I hear the sounds though, the less I think it is solely the exhaust. Especially since for me it is sometime cyclical with a roughly 2-3 second period of on and off.

Do let us know.

 

[trusted]

On a different note:
Drove the car for the first time in the low 40s last night. I did notice that the engine-turbo-exhaust symphony changes quite dramatically depending on the outside temperature. Also was surprised to see that the turbo still builds up to 20psi even when it's that cold. Car definitely feels faster then in the 90 degree muggy summer heat to me. (My Macan didn't do that. It adjusted the turbo pressures to the ambient temperatures and always felt pretty much the same.)

 

[jt4006]

I too notice a tone at idle when the engine is up to temp. It has a long period and takes a few seconds to rise and fall and is not always obvious; sometimes I hear it others times not.

 

[Fliz]

I too notice a tone at idle when the engine is up to temp. It has a long period and takes a few seconds to rise and fall and is not always obvious; sometimes I hear it others times not.

Aha. That sounds like what mine does.

Maybe we can correlate based on year/model/options.

I have a 2018 Boxster S with manual transmission but without PSE.

How about you?

 

[TheLip]

The last test drive that I took of a manual 718C, when I opened the window, I could hear a very noticeable whine as I accelerated. I assume that was the turbo as it rose in pitch as I accelerated. Schematics for the car show that the turbo intake is on the left side of the car which is the side we Americans drive on. Is that the sound that you are hearing? Does anybody else hear that turbo whine with the window open (or in a Boxster, with the top down) or was I driving a car that hadn't been properly PDI'd?

 

[Fliz]

Schematics for the car show that the turbo intake is on the left side of the car which is the side we Americans drive on. Is that the sound that you are hearing?

I don't think it's the Turbo because the sound is at idle and is cyclical i.e. on for a few second then off for a few second etc. Though... i wonder if some of the wizardry that is supposed to keep the turbo spinning could have something to do with it.

If anything it seems to go away when accelerating though it could simply be masked as it's pretty faint.

I'm going to try to characterize it some more. So far I'd say:

-at idle in non-sport or sport
-cyclic: on 3 secs, off 3 secs etc etc
-intermittent
-can hear it during accel
-doesn't seem to happen when car is first started... has to be at least a little warm or fully warmed up

 

[TheLip]

I don't think it's the Turbo because the sound is at idle and is cyclical i.e. on for a few second then off for a few second etc.

Do the revs fluctuate when the sound transitions from on to off or off to on?

 

[Fliz]

Do the revs fluctuate when the sound transitions from on to off or off to on?

No, I don't think so. I will verify tomorrow to be sure, but it seems like the revs are stable and at idle (~800-ish rpm) when this happens.