2 units are at the intake box, it is very easy to change.
I believe these two are; sound symposer and air cleaner box flap.

 

Another one is located at the far right in the engine bay, this is for water tube & heater.

 

3 units are located in the same area, it is quite difficult to see but it is changeable by hand.

- PSE Exhaust
- Tuning flap
- Engine coolant

 

Then for PDK, these two are the most critical.

You need to lift the car up and remove the protection tray underneath the car, you can see the PDK and you will easily find these two change over valves. Again, pretty easy to change.

 

It is recommend that you should check if the new one is working properly.
This is easy to check by connecting it with 12V battery then you should hear the sound as well as a little vibration.

You will not hear or feel anything from the bad one

 

This post is a little bit off the topic but I took photos of the PDDC system for those who want to see it.

 

Thats fantastic information iambon.
Thanks for posting.
I commend you on doing this yourself instead of hassling with the stealer.

I think my PSE valve is bad and who knows what others.
Although, I want to put a bad valve on the Symposer to keep it from opening..

What do you think the Air Filter Flap is for?
Is it just sound or flow/performance related?

Did you save your bad valves?
If I wanted one, would you accept a new C valve, in exchange for a confirmed bad valve, that is stuck closed (not open).

Do they always fail closed or open or either?

 

Hi thank to you too. I get a very good info from this tread.

- The tuning flap is for tuning the internal flap inside an intake box. It will open more when the rev is higher. This one should affect the performance.
- The air cleaner box flap, I am not really sure what it is but when I found my bad one with PSE, i switched the bad one from PSE to air cleaner box flap while waiting for the new spare part to arrive. It does not seem to affect any performance.

I did not keep the bad one but if you want then i can ask the indy shop if they still keep it. I am not sure if the bad one is struck in which position: open or close. I just know that a bad one for PSE is struck at open position since there is sport sound.

 

Thanks - aside from the labour, what do these babies go for and why wasn't this under warranty?

Does ANYONE know if a faulty one of these valves can cause the hesitation/ dead spot?

 

Hi,

One day I found out that I lost my PSE sound and my mechanic found out that the change over valve at exhaust was dead. They will replace it under the warranty however, they will not replace other good one.

According to the tread, Porsche is already issued the recall campaign to change the defected valves due to the seal problem however I live in Thailand and there is no recall yet.

I don't want to wait for it to fail and cause more problems so I ask my Indy shop to replace all since it is quite inexpensive (35 usd each).

They have removed the old one and re-checked if it is still working ok. They found out that three of them were dead. I am lucky that the bad valves are not controlled the critical components such as PDK heating system or engine coolant.

My Indy shop said some cars has heating problem due to these defected valves. You can imagine if this happens to PDK or engine coolant!

So they are controlling various components which should affect the performance of the car so it is well worth for me to be proactive.

 

Paid about $50 a piece (replaced the first three with my Indy shop. Started to work on it myself as I thought it was related to my aftermarket exhaust...). Porsche checked the other 5 but would not replace them as they were OK. A bit shortsighted IMHO.

I may have posted already, but someone mentioned on RL that Porsche has released a Technical Bulletin on this issue.

Not sure about the 'dead spot' have not observed it myself. Maybe a slight hesitation under full throttle that would be linked to the change of the intake flap position???

 

More like a stumble. Car jerks for a second..

 

Not what I have experienced, either when the intake flap valve was broken or working. I just observe a lack of linearity during hard acceleration around 2,500-3,500 rpm (engine sound more so than butt dyno). It is, I think, consistent with the torque & power curves of the 991S.

 

I wish it were that same for me.
The problem was fixed (albeit briefly) and came back with a vengeance.
After driving other 991's, this behavior is outside of the normal torque & power curves.

Will test the intake flap and figure out a reset of the DME. See where that goes.
Sadly the dealer won't do squat without a code..

 

After driving in the East Coast monsoons over the last few days, the car today sounded markedly different and much more drone in the cabin

Given one of the original issues with the changeover valves campaign was weather proofing, I suspect i have one that gave up its ghost in the rains. ( I had them all changed last year when the campaign came out).

I do not have PSE, but understand that there is a valve in the stock exhaust, too? (I do not think it is my sound symposer, because I have plugged that hose.)