Hi all, sorry if you saw this on the RL forum, just posting here as well for anyone who may not be on RL as I've lurked on 6speed forums for a while and there is some great advice here and would love any input:

Hi all, long time lurker and lover of all things automotive! I've perused the forums for common 1st gen/955 CTT issues and have looked at several, but there is one around me that I'd like some advice on a few things if you would be so kind!

First off, I'm no stranger to other german makes and have had and personally maintained several Mercedes and BMW, and I'm not afraid to do some of my own wrenching and diagnositics (i've rebuild air struts, repaired MB PSE air lock pumps (for the door locks....yes it IS stupid to use pneumatic door locks and soft close actuators when every other manufacturer uses electric motors), coded key fobs using programs like AK90+ (so you don't have to pay the dealer to install a new DME/immobilizer when you need new BMW keys), etc...not saying I'm an expert on anything, but just that I should be able to handle minor to moderate issues if they arise).

So enough BS (sorry!) heres the lowdown on what I'm looking at:

Overall a very clean 2004 (approx 130K miles) CTT that runs smoothly and exterior is in great condition, as well is the leather and interior panels. There are three main issues that I saw (1-2 of which may be user error on my part/lack of familiarity with the CTT):

(first off major common things have been done at local Porsche dealer: coolant tubes, cardan shaft, and coils (only 3 replaced...if I get it I will just replace all remaining originals as a precautionary)

1. What level of boost should register on the right hand side of the cluster boost gauge? I drove it around a bit granny-ish and am ashamed to say I never exceeded much over 3500 rpm, I don't recall seeing the guage move but wasn't paying close attention - later while parked I revved to around 2.5K rpm and didn't see the needle budge...on other cars I've had that are TT's (no german makes though) and it seems that the boost guages would move readily even if a single turbo car and would show at least some small movement even at lower revvs (maybe build 2-3 lbs of booost?)...maybe I'm just not thinking right and I just need to go stomp on it and take her to 6K and see if it moves...my question here is: What is normal boost levels for a given rpm range? (from looking at prior posts it seems that even on the highway accelerating moderately you should see the guage move...those posters with no movement were later found to have a boost leak, often involving the N75 valve)

2. Transmission seems a bit harsh while shifting..still gets into each gear fine (under 2K rpm at 65+mph and had 4 'shifts' so was in 5th gear)...this isn't an earth shattering clunk, but just a bit harder that a benz or lexus...is is normal to have a bit harsher shifts on a Cayenne?? I was expecting if there was anything trans related it would be the 4-5 kickdown issue that was from a sticking valve body (or maybe this could just be the valve body as well if a typical CTT is silky smooth??)

3. Radio not connected...an aftermarket radio was in, but now the original unit with Navi is back in and I'm told the the present owner that he 'did not want to pay $1000 for porsche to hook it up....) should I assume PCM/elect issues (obviously we are going to the dealership the aftermarket unit was removed at so they can give the full story, but I wondered it it was a tell tale sign of issues (all other electronics work on dash and climate control etc). Anything to worry about here specifically or to ask the dealer about?

Bonus question: any other things I should look closely at/have the Porsche place look close at that are rarely discussed on here (ie that I may have missed in my common issues searches)? We are taking it to the same Porsche place it has been serviced at and it is also where 3 friends of mine (who have 993's, 911_50, and cayman) go to regularly (and they gave me the name of the 'best' mechanic to ask for for a PPI).

Anyways would greatly appreciate the input (and obviously the possible issues are priced into the car or will be on negotiation so I will be sure not to get it if the cost plus repairs approaches what a sub 90K mile example can be had for around me)

Thanks for all responses!! You all/this forum is a great resource!

 

Cayenne is gonna shift some what hard. Def hared then a Benz, the shifts in my Sclass aren't anything like the Cayenne. LOL.

Get that radio hooked up, if it was aftermarket it was replaced for a reason. no one replaces a perfectly good radio...

Check fuel pumps...

 

Rather obvious things:

1. Coolant pipes under the intake manifold. Have they been replaced with the aluminum ones. This is a WHEN job not an IF job.

2. Cardan shaft center bearing support - when's the last time/mileage it was replaced?

3. Hard trans shifts can be a sticky valve body. There are fixed valve bodies available - figure $1,500-$2,000 or so if you have someone do the whole job.

4. Radio/PCM - uses an optical fiber loop - that has to be in place for everything to work right. If it's not - $$$. Not too many places can troubleshoot it - most just throw parts at it.

Boost - I'd expect to see some. Not a lot - perhaps 1.5-2 bar under moderate hard acceleration in 3rd gear. The problem seeing max boost is you're already WAY over any speed limit in the US before it hits max boost.

 

Thanks for the reply!

I'll def get the radio looked at, sounds like an undertaking similar to an S class radio (fiber optic system as well)

Glad to hear the shifts are more noticable so it may be normal operation..I will still ask about possible valve body at PPI

Thanks for the heads up on the fuel pump, does that just mean look for rough idle or cutoffs at high rpm (ie are the fuel pumps known issues in the 955's?) thanks!!

 

Thanks for the reply!

1. Yes coolant tubes done in last 40K miles

2. Cardan shaft done approx 30K ago (I think they go about 50-60K before ideally replacing again??)

3. Thank you! I was planning on this being about $2k for a fix, seems like valve body is the main issue as I don't see many/any complaint of trans failure completely (clutch packs etc)

4. Thanks, def gonna get the radio investigated at the dealer (they should know as they removed the aftermkt unit), sound like a MB type of issue as there is no easy plug and play/fiber optic connectors

5. Thanks, I'll def look close under spirited driving...seems like if there was zero bar showing at all times there would be a check engine light or code or something to key off of, but it doesn't appear to run rough or anything even when driving 65+mph

Thanks again!

 

Look for engine cutting out or hard starting for fuel pumps. They'll prob go soon...

I hated the radio in the S class lol, just remember that Porsche have to be driven, not just driven, like you stole it. They'll break/ start to act up if you don't drive them. I try and drive mine every other day.

 

Thanks! Yes there was nothing that seemed like cutting out, but given the responses here from you guys and from further searching it looks like this one won't be worth it vs getting a fully sorted lower mileage CTT (this one is around 9.5, and even if I got some knocked off I'd rather pay 12-15 for something with no questions as it looks like the radio unit alone could cost a few grand if there is damage to the fiber system - not to mention a possible need to look at boost issue and valve body!). Thanks for the input, I'm definitely going to hunt down a CTT, - this one just had my attention because of convenience - the owner lived just a few minutes from me...but we all know how those stories go, don't buy something just b/c it's close by or convenient as it will likely cost you in the end to not make the effort to find a better example!

 

The factory boost gauge on a 955CTT only shows .8 bar max. If you were driving timidly it may not have been boosting hardly at all. Parked it won't move. Take it out and find someplace safe and flog it a bit. I made the mistake of NOT doing that when I test drove mine and paid for it later. Find a parking lot or long stretch of road and have someone watch the boost gauge. When flooring the throttle it should peg the needle at .8bar and hopefully hold there or near there. You don't have to keep going to 165mph watching it, but let it shift at least into 2nd.


If the valve body is bad it will show itself pretty well by cruising along at about 50 and then flooring it. Felt like hitting a stump, it was a violent and LOUD thump. I really thought I had hit something or broken the driveshaft it was that bad. I suppose not all will diagnose the same way but as soon as I pulled over and googled the symptoms I found many links saying the same thing.


As for the stereo if this is a good car other than that don't worry about it but go have a decent aftermarket system put in. The nav is garbage and the Bose sound is only semi-decent. You can get a good system for less than trying to fix the original.


Just my $0.02.

 

Thanks! thats very helpful on the valve body, I just wasn't sure the extent...it looks like the more I search it seems to be an 'if' not 'when' as many of not just the CTTs but also CS's seem to have had this done even by 70-80K miles (probably age is a factor with many 955's getting up there at this point).

Thanks again! I'll definitely take the advice on the stereo as well

 

I know you prob want a TT but maybe look at the S's also, they're not so bad lol. Turbo does have some features that I wish mine had like the headliner, so I can't blame you. But don't settle. If you really like the one that's closest to you, buy it. Take the risk!

 

Mine was pushing 10 years old with about 75K miles on it when I bought it. The valve body was bad when I bought it. I didn't figure it out until about 3 days later. Not a big deal if you are a DIY kind of guy. ~$1000 to swap in a rebuilt one.