leftlane

Hi all -

I am taking my 14 GTS in for service tomorrow - oil change and to try to find a vibrating rattle somewhere in the dash.

My bigger concern is hard downshifts that literally throw me forward when I brake. If I am cruising along at 50 mph and need to brake for an upcoming red light, my car is insistent on hitting every gear on the slowdown and really bangs hard from 4-3 and 3-2. It is the most jarring shifting I have ever experienced in a car and I am not driving it aggressively at all. If I give myself a long runway to slow down it is much smoother, but sometimes the light turns yellow up ahead and I need to brake with more force - and bang bang bang.

I'm sure I can reproduce with a tech tomorrow, but any idea if this is transfer case or tranny? All other aspects are totally smooth and I love the car, but hate these downshifts, especially when someone else is in the car with me. It is that bad.

TIA,

Todd

elite1

Do you have sport mode on?

My Turbo does this same thing with sport mode on and is less pronounced with it off.

ScootCherHienie

Make sure the differential lock is not activated (if you have that setting on 958x, I'm a 957 owner). Locking the diff is only for off-road use.

CarGuyNVA

The symptoms you describe sound like the 955/957 gen Cayennes that experienced transmission valve body issues. I've never heard of that problem though with the 958s?


And I doubt it would be this severe just because sport mode is enabled. You do get sharper more pronounced downshifts in sport mode especially when driving in a spirited fashion, but I'd never consider it severe or harsh in it's operation as you describe. Something else going on here.

leftlane

I drive in Comfort mode all the time with the air suspension in the middle and no diffs locked. I also never use the tiptronic buttons - I just let the tranny shift on its own.

Dropped it off today and was able to replicate for the tech so we'll see what they say. Sometimes it gets hung up in 2nd gear after downshifting if I start to accelerate again without coming to a complete stop.

Service advisor said he's seen some transfer case issues but never in a GTS.

It seems to happen only when I get all the way into 8th gear and then have to stop a little more suddenly and it is intent on banging through every gear on the way down and not skipping any.

CarGuyNVA

Please let us know what you find out. I'm thinking transfer case, although the symptoms you describe are different than what most of us have experienced with a failing TC. Hopefully it's not the transmission itself.


Again, please let us know when you get a solid diagnosis on it.

leftlane

Will do - even though I demonstrated it to the tech when I drove with him, the advisor told me today they find no faults and no abnormal behavior. I told them to keep looking - it is obvious and I'm tired of dealers saying they can't duplicate when I already showed them and it is pretty consistent.

Stuff like this is frustrating and it makes me very irritable. I think I'll call it a day and go get a margarita.

abiazis

I had very same complaint with my 14 GTS and had mine re-flashed or reprogrammed according to service receipt. It is much smoother stopping now. Satisfied with the adjustment. Your dealer should know how to handle.

leftlane

Thanks abiazis - the first time I brought it to the dealer (different one) they said they did that but I didn't notice much of a change. I changed dealers this time because after the first one having my car for a week for a dash rattle and this shifting issue, I got it back with a dash rattle, the shifting issue, and 4 trim pieces put back together incorrectly or not at all. Ain't nobody got time for that.

I love this car and I'll get it squared away. I'll report back for the benefit of others when it is done.

leftlane

Got the car back today - basically inconclusive. The tech said he can find no issue with the shifting, there are no faults, and everything is operating as designed. We went for a ride and I demonstrated the hard kickdown shift and he said it is normal. Another tech thought it was ABS kicking in but that is definitely not it as there is no pulsing in the pedal or ABS noise anyway.

It's documented now and he told me to bring it back in if I feel it is getting worse. I'm not going to worry about it as I tend to make things bigger than they need to be.

He was very familiar with the transfer case issue and said I certainly do not suffer from that.

ScootCherHienie

If this vehicle has been driven for some time WITHOUT doing this and is now doing it, something is definitely wrong in spite of what they say. If this has been happening since you acquired the vehicle, perhaps you should drive another one that's for sale somewhere to see if it does the same thing with you driving that one.

leftlane

Good point - it has not been getting worse and it didn't just start. I had it in once before to a different dealer and they supposedly updated the software, but I didn't notice any real change.

The most likely scenario is that it is normal and I am an idiot trying to manufacture a problem where there is none. I blame this on my prior BMW 750 ownership experience where everything that could go wrong did go wrong.

I'll see if I can drive another GTS to confirm.

cuttinsod

check this out... https://rennlist.com/forums/cayenne-...d-driving.html

elite1

I could be completely wrong on this but, I really think you're dealing with the Porsche's shift point adaptive setting. I don't think you will experience the same situation by driving another GTS unless you drive under the exact same conditions.

I drive 2.3mi's daily and not aggressive. My cayenne is very sluggish for this duration. Seems I'm in 8th gear all the time.

During the weekend when I drive on the highway and get to enjoy the power a little, I encounter this hard shifting sequence, especially on offramps under braking. This shifting sequence is powerful enough it does throw me forward a little.

I experience this same behavior Monday, even Tuesday morning on the same 2.3mi route. Back to a sluggish behavior on hump day.

On a positive note, this radical shifting behavior does knock a few secs. off my commute time.

deilenberger

Yup: https://rennlist.com/forums/cayenne-...l#post14502895