gimp2x

Cayenne 955 Turbo S

I've got a new valve body in my transmission, fresh fluid/filter- all of that is in order

I still get a rough shift from 2-3 and coast down from 3 -2, I have a valve cover leak on the passenger side that I'll be fixing when the new seal arrives, I've replaced almost all of the vacuum system, check valves, air/oil separator, filler cap seal, throttle body seal, etc- really running out of places a leak can be.

I do not see any posts on here of those with valve cover leaks having erratic behavior out of the drivetrain, so I was curious if others can share their experience.

Dilberto

You should have added Lubegard Universal, when dropping the new VB inside

gimp2x

Brainz

Vacuum leaks will create the weird 2/3 shifting you describe. Likely candidates include the vacuum line to the brake pump, and the lines under the throttle body including potentially a leaking purge valve. I suppose if the valve cover gaskets were leaking, that too would be suspect.

gimp2x

Brainz

One more thought, having re-read your original post: Did you have this 2-3 shift issue before you replaced your trans VB? If not, I suspect your trans may be underfilled. Read my post on this thread: https://rennlist.com/forums/cayenne-...ssue-help.html

Note that the 2/3 shift can also be related to vacuum leaks, but given the recent transmission work (and frequent underfilling), you might want to re-focus there. And per Dilbertos suggestion, I agree that a bottle of Lubegard Red seems to make things smoother.

J'sWorld

Did you reset the adaptations on the trans control unit? This needs to be done.

gimp2x

Yes, I reset the adaptation, I will flush the fluid and refill to 35deg C and see if that resolves it, new valve cover is going on this weekend

I find this particular behavior to be quite frustrating and the dealership did not seem to know a resolution to it, other than you need to replace your transmission and transfer case (cost prohibitive solution on a car of this year/age)

Will report back my findings, I'm determined to resolve this

nodoors

Any luck?

gimp2x

gimp2x

This engine vent line/breahter hose was bad so we are ordering a replacement one, we repaired the existing one as best as possible with heat shrink, but until the OEM part comes in and goes on, I'm going to hope this is to blame



https://www.ecstuning.com/b-genuine-porsche-parts/engine-ventilation-line/94810721552/

PTEC

I have seen transmissions act funny when there is a intake leak. A pinched or badly leaking valve cover gasket might let enough false air into throw off the reading. That breather pipe is probably broken on almost every cayenne turbo on the road so I doubt its your problem but still think you should go ahead with replacing it. Are you hitting full boost when you're at full throttle? Should hit 1.0 bar for a bit then taper back as the rpm gets higher.

Brainz

I think you're on the right track. More trans fluid and replacing that breather should both help your symptoms. Underfilled trans and vacuum leaks == Cayenne driveability and shifting weirdness.

gimp2x

we had smoke checked the intake path (air filter -> throttle body) and not found a leak, we believe this hose was damaged when removing the valve cover for that gasket replacement, here's what the valve cover gasket leak looked like:

Brainz

And keep resetting the transmission control module with each change. Also, consider driving with the PSM turned off (button above the NAV) for the first couple days post reset. In my experience, that will cause your shifts to be more firm and generally snappier as the transmission learns your preferred driving style. I eventually got mine exorcised of the weird-shifting-demons, but yeah, it can be a frustrating process of elimination...