david996

I have a 2004 Cayenne Turbo that has a vibration or shudder below 2000 rpm regardless of the speed of the car or the gear it is in. It also regularly feels like I just went over a washboard surface at low rpm even though the road is smooth. I have replaced the transmission and had the driveline indexed, both by the dealer. On the highway at 80 the car is smooth. Does anyone have any suggestions? Thanks.

r553

What are the condition of your motor and transmission mounts?

david996

I would assume that they are in good shape because the dealer told me they had to drop the engine to replace the transmission so I would think that is something they would have checked but who knows. I will take a look. Thank you.

r553

Was the vibration present before the transmission was replaced?

david996

Before it was replaced, there was a very slight vibration that the dealer attributed to the transmission and only started in the week before it was replaced. Before that, there was none at all. Now the shudder is much more noticeable unless I manually keep the revs above 2000 rpm. I replaced the transmission because the clutch pack failed and while it would shift very smoothly if I let off the gas at 2500 to 2700 rpm, it would downshift rapidly on moderate to hard acceleration and then would either not go into gear for a while or would violently clunk going back in gear. I have to believe that with the mechanics making this fault happen over and over again that they damaged something in the drive train. The car has 90,000 miles and does have a replacement driveshaft from the prior owner, who knew the transmission was bad but didn't tell me. It also has an aftermarket exhaust. The mechanic did check the valve body in the original transmission, thinking that was the culprit, but determined it was working properly. I never experienced the washboard symptom before the transmission was installed. Thanks.

r553

I believe your engine has torque dampers ( one on each side ) that may cause vibration when they fail. They connect the cylinder heads to the body and are easily accessible in the engine bay.

https://www.pelicanparts.com/techart...eplacement.htm

Here is a link for replacing the motor mounts:

https://rennlist.com/forums/porsche-...he-mounts.html

david996

Thanks again. That looks pretty promising as a fix.

r553

You might examine your bill from transmission replacement to see if new motor mounts , subframe bushings or torque dampers were replaced. Also the fact your car is a turbo may make mount replacement more difficult. I hope it turns out to be something easily replaceable.

david996

Thanks. I’m hoping it’s the torque bar at the top of the engine because that’s the only fix I could do myself.

MAGK944

dr914

it usually is always the driveshaft maybe they should check again

david996

Hi Tia:
The problem was with the transmission that the dealer installed. They had agreed to install a brand new transmission but instead, without my prior knowledge, installed not only a remanufactured transmission but the incorrect one for the vehicle. While I was able to reduce the vibration by replacing pretty much everything under the sun, I was never able to eliminate it. The car did not have that issue before the dealer replaced the transmission. I ended up trading the car in when other things started to go wrong and took a huge hit. The only advice I can give is stay away from the dealer and find a good independent mechanic. Best of luck.

Brainz

Sorry to hear about your [expensive] situation -- wish it'd turned out better.

Out of curiosity, did you replace the Evap Purge Valve? I ask, as that was determined to be the cause of my "washboard" rumble around 2000-2500 rpm on my 2006CTT. My theory is that the valve fails open, creating a vacuum leak that seems to play havoc with the transmission controller which appears to use manifold pressure as an input. I think what it does is confuse the TCM and disrupt torque converter lockup -- as a result you get a slipping/judder from the torque converter that feels like a washboard road under certain rpm/driving conditions. Note that I had no idea my purge valve was bad until I started getting the usual hard start after filling the fuel tank. But upon replacing the purge valve, not only was the hard start fixed, but my washboard rumble was exorcised. Weird.

david996

No, I replaced the cardan driveshaft, motor mounts, tires, the support for the transmission, the upper engine support and had the driveshaft balanced. I may have also had an issue with the transmission controller but did not replace it. After spending over $20k on repairs, I just gave up and decided to live with it.

Brainz

Ugh. Sorry to hear about your experience.