Yes thanks for your description of the behavior.
Obviously there's lots of expertise here, maybe someone with knowledge can help.

It appears to me the TC only meters torque to the front wheels, that it cannot cut torque to the rear wheels.
The rear wheels are direct-drive from the transmission.
Consequently, -----> if there is a power loss to the rear wheels, it has to be the transmission that is slipping, not the TC.

Am I correct?

I'm a 'new' Cayenne owner, just trying to understand the drive system and this TC problem.

 

Doug, did you get a new one recently?

 

Welcome. Basically, only thing to do is change TC fluid every 10k-20k miles. Some people are happy with this but personally I am not.

 

From what I read, they’re replacing with more of the same. Nothing changed. From what I read, P decided to cheap out and use a VW toureg TC instead of getting a new one built for Cayenne. Cayenne requires a larger sized TC than VW therein lies the problem. But they keep replacing them with the same TC. This is what I found out during my research.

 

My dealer replace my 2016 TC in September. The warranty expires in August 2022. The dealer recommended at least bringing it in just before the expiry to have the fluid changed and then if anything goes wrong afterwards they would go to bat for me with Porsche. So I agree, the problem is not totally fixed but is better and fluid changes will help if you plan to keep it to a high mileage.

 

That’s a good dealer/advisor.

 

Got the call from dealership here on Long Island that the TC is bad and they will be getting a new one in for the Cayenne. All covered under the recent 10 year warranty.
I'll report back on how it goes.

 

No. Just curious if you guys came up with a new protocol.

 

Huh? I am not sure what kind of garbage information you came across in the research you did, but the active clutch transfer case that has had historical issues in the Cayenne (which this thread is about) is not the same as the VW toureg self locking differential transfer case. Nor is the current Porsche Cayenne active clutch transfer case replacement exactly the same as prior units.

 

Can you share the sources of this research with us? The diesel TC is basically a VW case, but the gasoline-powered ones are not. I'm curious where you might have seen something claiming otherwise.

 

To close the loop on mine, they drove it felt the jerking, disconnected the awd connector problem confirmed. Replaced the transfer case, control module, vent line and spacer ring. It is now smooth and good to go.

For a brief time they lost the canbus system and wanted me to authorize 1 hr of time to diagnose the Cayenne apparently healed itself 25 minutes however so I am guessing they missed a connection. Waited on site took about 4.5 hours from check in to out the door.

 

OK so can someone critique my "understanding" of this problem?
I've read a lot of posts, which is time-consuming, but I think I have it.

=================
My current understanding:

The Cayenne is direct-drive to the rear, with an active, computer-controlled clutch that engages the front axles to make it "AWD".
The active clutch system squeezes the clutch disc pack and throws power to the front axles upon command from the traction-control system.
There is some mechanical component squeezing the clutch disc pack too.

The jerking is the front axles clutching in and out, which is the Cayenne alternating between 4wd / 2wd / 4wd / 2wd.
Consequently you have to be accelerating hard enough for the rear wheels to be breaking traction, to feel the difference between 2wd / 4wd / 2wd / 4wd

When you disconnect the electrical plug, the Cayenne becomes a rear-drive 2wd and cannot do the 2wd / 4wd / 2wd / 4wd.

Without electrical signal, is there NO squeezing of the clutch pack?
Or is there a little squeeze, such that the clutch slips, and wears out, contaminating the oil?
And as such, changing the oil often buys time.

So is this a problem that is felt only by drivers who 'get on it'?
Would a driver who never pushes hard enough to slip the rear wheels never notice a TC problem?
Or perhaps this gentle driver simply never wears out the clutch pack?

I see a lot of folks here navigating the warranty program and I'm happy for that info, but I'm kinda interested in understanding the mechanical part of the problem too.
Anyone whose car is out of warranty, or the extended warranty, should be interested too.

I'm being rather persistent on this, If you all don't wanna get into the mechanical part - please let me know if you think I should post a new dedicated thread to TC internal operation.
Or does anyone know a better thread for discussion of TC internal mechanics?

 

Ours did it under light or heavy throttle application.

I would think that if you are seeing the problem cured by swapping out fluid that it is not a wear issue with the clutch packs. Fresh fluid wouldn't correct that but it would remove contaminants from the system allowing for normal operation. My plan moving forward is to do the transfer case fluid change regularly to keep it healthy

 

Agreed fluid change solving the problem tells you the clutch pack is not yet worn out.
Problem with that is, other fellers who wear theirs out, get new TCs.
Prob better to wear out the 'original', get the replacement TC, and baby that new one with frequent fluid flushes.

Interesting that you could feel it under light acceleration.
This is messing with my understanding of what the TC does (which is engaging the front axles upon command).
Could you feel the jerking on light acceleration __on dry road__? Or Wet road?

 

You could definitely feel it under light acceleration dry or wet conditions. They ordered the case in so it was there when I brought the truck in. They just confirmed it was acting up and then swapped the parts. No attempt at a fluid change by the dealer If they wouldn't have replaced the case, I would have done the change and gone from there.