Cayenne955TT

Hello,

I have a strange issue with my Cayenne's air suspension. The car will go up and self level no problem, it also doesnt leak either. However, when going down, it seems that it is having trouble dumping the air. The front end responds rapidly, but the rear (and it seems the rear driver side) seems to not want to drop air pressure. When this happens, the air suspension times out and throws an error. This error resets on restart and the suspension will generally settle out while driving/over time. Is there a bad check valve or something that could be causing this issue? Normally air suspension leaks on cars, not so sealed it wont drop!

-Will

hopsis

Could be the drier "cat litter" is not doing its job any more and there is moisture in the system. That moisture then freezes the outlet valve when blown out.

Cayenne955TT

Where is that located? And would that be a problem when it is 90 degrees out and only affect one of the air shocks (or two at most)? I know phase change, etc but still seems a strange

-Will

hopsis

I guess the outlet is somewhere near the compressor. I'm not sure if it could affect only one corner.

TomF

It is most likely the air valves on one or both sides of the rear. If you are reasonably handy mechanically, you can replace them both in less than an hour. See my comments in this thread:
https://rennlist.com/forums/cayenne-...-question.html

Cayenne955TT

Bingo! That sounds just like my issue. I'm going to live with it for a few weeks (as long as I dont move the suspension it doesnt give any issues). I have to do a big order soon (oil change, new brakes all around and those air fittings) so itll be a full day of Cayenne work. I bet that solves my issue. It didnt used to be like this and no other variables changed so that sounds like the culprit.

-Will

TomF

If changing out the valves doesn't remedy the issue, the other possibility is that the rear PDCC distribution block has a stuck or failed solenoid. This thread (do a "find" for solenoid, as it is rather long, but very good!) has very useful information. At some point, I plan on pulling both distribution blocks out of my 2009 CTTS and giving them an overhaul.

Cheers,
Tom

Cayenne955TT

Good call - Air components lasting this long without any work is already a miracle. This might sound dumb but is there any place or reason to ever lubricate the air system with anything? I know on certain military vehicles there are a bunch of air system problems that can be avoided by occasional air system lubrication...

-Will

TomF

Okay, my bad. Somehow the link to the thread I mentioned above about the distribution block got left out. Here you go.... https://rennlist.com/forums/cayenne-...yenne-gts.html

Cayenne955TT

Thank you - very cool thread on that 08 GTS. Lots of reading to do!

-Will

TomF

As a followup, my other air valve, on the driver's side rear, failed yesterday. Interesting that it didn't throw any code, however. I happened to notice unsettled handling in Sport mode. I am going to replace it and see if that is indeed the problem. I think that if it is a failed valve block solenoid, it would have thrown a code as in the thread I linked to about the GTS.

TomF

A quick update- I replaced the driver's side valve this morning and the uneven ride height issue went away.

A couple of observations:

1. If you are not using the benefit of a lift, ensure you know EXACTLY what will change in the suspension geometry before you let the air out. Failure to be safe here could result in death or arm amputation. Make sure the frame is supported on jack stands in multiple places.
2. Let the air out of the line slowly... for safety's sake.
3. If you are not staring at the bottom of the end of the gas tank, when lying beneath the vehicle, you will not have the right angle, nor the leverage, to remove the air line and the valve itself. I am 6'2" and 180 with pretty long arms, so take that into consideration.
4. It is done almost completely by feel. I finally gave up on my lights and did it by touch.
5. Prepare to be pretty bruised and banged up on completion.
6. The parts were less than $100, with about 2 hours of work total. A shop will have to dismantle everything and this will cost about $500 per side. Unless you are fully refreshing your suspension or rebuilding your air shocks, it isn't worth it having the dealer rip it all apart.
7. Have a beer or two when you are finished- it helps with #5 above.

Cheers,
Tom

Cayenne955TT

Tom,

Thanks for the extended follow up! I have actually been up in that area before where the air valves are located so I'm well aware of how awfully tight it is! I will probably just wait a few weeks until I can throw it on a lift/change the oil at the same time to take a look. I really dont change the suspension setting ever so as long as I dont change it, there is no problem. Good call on the safety factor though....with a complex suspension as on the Cayenne once that air lets loose everything gets wonky.

-Will

gundrted

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