GVA-SFO

Since few months, I replaced our old 2006 Cayenne S Tit. Ed., that had air suspension, (we did around 110k miles with it), against a 2011 CTT.
We always felt that the car was very comfy, and enjoy all the rides.

The CTT is an incredible SUV, but we have something VERY wrong : the comfort is just awful. It looks like the air suspension is stuck on a kind of “super stiff mode”, and when you try to go to “normal”, or “comfort”, it makes no difference at all.

It is true that we have not the tires that I used to like VERY much, i.e.: the Vredestein Ultrac Sessanta, but we have Continental M+S Cross Contact LX Sport (N0). Both are/were on 20” wheels.
Tire pressure is checked and is OK.

Anyone would have comments/ideas about the potential source of such behavior ?

Are the Conti being the culprit ?
Or, do we have suspension problem. (Piwis reading shows nothing wrong at all !)

GVA-SFO

Shall I understand that I'm the only one with this "stiff" problem on air suspension ?
(I can mention that I have a "fun/track" Boxster S, that have Bilstein PSS9 on each corner, ..and, the Cayenne is not really more comfy !!!)

mudman2

I wonder if something has been added, what about ride height, does that adjust ?

BlackTurboS

First thing I would do is check your PDCC resevoir. I'm fairly new to the Cayenne game as I've had my 09 Turbo S for about a month, but I did tons of reading before buying it. I would double check the PDCC resevoir to make sure you have plenty of hydraulic fluid, no lines are leaking, etc. In the weeks/months of research I did prior to buying my cayenne, this seemed to be a recurring theme every time there was an issue with the air suspension. The PDCC res is supposed to be replaced every 60k miles, I don't think porsche would recommend that unless they were known to occasionally fail.

If there is fluid in it, you may need to bleed it and empty the resevoir. There may be an air bubble/dirt/etc in the lines that are preventing the suspension from getting the fluid it needs to adjust. Just my ideas, sorry you are having the issues

mudman2

The AIR suspension does not use fluid and is not connected to the PDCC.

When my PDCC went the sway bars were inop

BlackTurboS

Shows how much I know! Thanks Mudman. I guess the PDCC is just for the dynamic control unit? Sorry for any confusion. I defer to mudman for sure.

endless_corners

PDCC is a hydraulic leveling system to keep the car flat on corners.

GVA-SFO

Thanks a LOT for the comments, was very happy to read.

Anyway, I do not think that I have PDCC, this is an option that is not in my list.
(Air suspension is standard on Turbo, as well as on GTS if I'm right !)

Yes, I confirm that the ride height do adjust as is should. I.e.: I use it all the time to connect and deconnect the trailer (I'm leasy !) or, : set the car "low" when backing up to be under the hitch, and then, set it "high", to connect it ! Idem, reversed to deconnect it !

But very clearly the ride comfort do not change if you select any of the 3 modes. It is more stiff than the sport mode was, (by memory) with our CS (a 955 that had air suspension), with which we had 110k happy miles !

endless_corners

Perhaps you are going to have to do the dirty. Take it to the stealer for diagnostics.

garrett376

It's not that the reservoir fails, it is because there is a built-in filter in the reservoir that can only be replaced by changing the entire reservoir.

GVA: something isn't right as there should be a significant difference between sport and comfort especially noticed on rough roads. And a properly functioning 2011 turbo has a very smooth comfortable ride in Normal and Comfort, and a nice stiff one but still smoothly damped in Sport setting. Have someone scan it with a PIWIS to see if the shocks/PASM are working right, though I'd think you'd get a chassis error if something was amiss, though there are a lot of system failures that produce a fault code visible with the PIWIS but do not show up as warnings the driver sees.

GVA-SFO

Thanks Garrett376,
Yes, it has been "Piwis scanned" at the "P" dealer (where I bought it), and no errors were reported.
I doubt that the Conti (M+S) are the culprit.
The good thing is the car is under CPO, but, will not keep it like that.
We had a CS Tit. Edit, with air suspension and put 110 k miles on it, ..before having this CTT, so, we have a good feeling of what it should be if the air suspension would work as it should.
Definitively something is wrong, ..but seems to be quite hard to find what !

Rennaissance

GVA, does your multipurpose display show anything when you switch between different PASM modes? It should display the selected mode when it is selected.

It seems to me like this is not a PDCC problem but a PASM / control unit problem. PASM sets the comfort modes, while PDCC maintains stability using hydraulics.

Here's some food for thought:

https://rennlist.com/forums/997-foru...t-working.html

http://carsguns.com/porsche/porsche-...-intermittent/

https://www.pca.org/tech/pasm-workin...ow-do-you-tell

http://www.6speedonline.com/forums/9...ilure-too.html

The links above generally refer to cases where an error message has lit up. I understand that this is not your case. Perhaps you should try going to the local Pep Boys who will show you whatever they see on the OBD II scanner. It might be that trouble codes are showing up intermittently.

Anyways, I hope the above links provide good suggestions. Feel free to contact me if you'd like to try our CTT for comparison (we met at PofB a month ago). There is a tangible difference between the comfort modes on our stock 21" tires.

GVA-SFO

Hello Renaissance,
Very nice to read from you here, and thanks a lot for your message.
Yes, when selecting the suspension mode, the displays shows the selection exactly as it should, but, ..the feeling do not change.
Thanks a lot for the links, I did check them all, but I'm still at the same stage, ..searching.
If you have time, I would love to do a comp ride, i.e.: to ride a same road together with both cars, and then talk ! We can each drive ours (no need to drive, the passenger get the same feeling) to get the feel of the ride. (Freeway / speed is not needed at all.)
By the way, I'm on 20" (which should play in my favor !), but I have (bought it (atPofB) with them) Conti "M+S", while I read you are in 21".

GVA-SFO

By the way, thinking to be prepared for such a ride comp, and thinking that an iPhone have accelerometer sensors, I went to the iStore, ..to find :
https://itunes.apple.com/us/app/icar...453239854?mt=8

So, it looks like we could have a serious and neutral judge with us !

(Just got the app and install it, will do some try.)

125shifter

My 2011 CTT is very noticeable from comfort, normal, to sport settings so if you're not feeling a difference something is wrong. I would likely leave mine in sport all the time because the handling is so much better but it is rough so I usually leave it in normal especially when cruising down the highway. Comfort is too soft and wallowy, best left for carrying old people and transplant organs.