AGARubberDuck

My 11 CTT is better than my previous 04 CTT in nearly every way, but I am disliking some of the transmission behavior. I'm looking for either "mine does that too, probably normal" or "Not normal Duck- get it checked out."

1st, and most noticeable, is that I can't engine brake like I used to by downshifting. Well, I can, but it is too jerky to want to do it. Say I'm coming to a stop and downshift from 3rd to 2nd with either no brake pedal, or only light brake pedal. I'll feel an immediate slowdown, followed by a period where it seems to be free-rolling, then a much more harsh slowdown effect. From 2nd to 1st produces the same effect, only much more jerky. That free-rolling portion seems inconsistent, but usually a lot longer than I'd expect. In stop-and-go traffic in automatic mode it can get quite irritating not being able to predict how much brake pedal I actually need to come to a smooth stop.

2nd, (less frequently encountered, but probably more worrisome) when having a spirited acceleration after taking a corner, usually from a stop, the 2011 wants to hold the gear WAY too long - to the point where it has actually bogged down bouncing off a rev limiter. Think, stopped at a 2-lane turn light. Green arrow show up and you blast away from the light, taking full advantage of the PDCC. About 1/3rd of the way down the ramp the revs are up much higher than they ought to be and there is no more acceleration to be had until an upshift takes place, usually about 3/4 of the way down the ramp. My 04 did this to some extent, but would never bounce off the limiter- and I could always manually select the next gear and it would comply. When my 11 refuses to shift, I cannot even make it do it with the paddles.

I mentioned this to my service adviser, but beyond stating that it was unusual for it to do that, didn't try and have their techs look into it further. I made the mistake of asking what it takes to check the transmission fluid level, possibly tipping my hand that I thought about what the problem might be (low fluid) instead of coming in wide-eyed with problem symptoms and an open wallet.

wkearney99

I found the way the transmission in my '17 'learns' to be somewhat quirkier than I'd expected. But I've never run into it hitting the rev limiter. I have felt what seemed like it holding a shift when the body was under heavy lateral acceleration (as in, heaving around a turn). I'm guessing it's wanting to avoid upsetting the body weight with an ill-timed shift while going around a corner. But I've not hit the rev limiter during that, perhaps only because of not being quite THAT aggressive around most turns. I don't typically need to bother with the paddles as it seems to be quicker/smarter than I'd ever be.

If you've got a repeatable stretch of road might that be a good place to demonstrate it for the service associate?

Downshifting manually for engine braking has always been a bit more aggressive than I would normally chose. Not dramatically so, but certainly more forceful than in other vehicles. I can't imagine doing it manually would be any smoother/better.

So I don't have a specific answer other than to say, yeah, sometimes the way the transmission learns shifts is 'interesting'.

deilenberger

The description you give of downshift behavior doesn't sound normal. At no time does mine feel free-wheeling. Makes me think perhaps transfer case?

AGARubberDuck

Thanks for the reply. It makes sense to not upset a corner with an upshift, and I get that. My issue is that going straight after an aggressive corner is still holding the shift too long, or maybe that it simply cannot shift due to some problem. (since I can't upshift manually) So here I am redlining at 60mph for about 3 seconds waiting.. waiting.. waiting for a shift. Kind-of a buzz kill.

I thought so too, so I did change out the transfer case fluid last weekend with the Ravenol off Amazon, recommended on this forum. I've since put on about 500 miles but figured I'd do the 2nd round over labor day. My original fluid was a bit dark, but not cloudy. My assumption is that water contamination would give the oil a milky look. Really no difference pre-post fluid change at all for me, with this behavior or any other driving characteristic.

wkearney99

Yes, when you add the detail of it holding the shift even after exiting from a weight-transition situation then it does sound like something's amiss. I don't know what it uses to determine readiness for shifting manually. How many miles on the transmission fluid? Not that I'd think that would cause shift-holding though.

AGARubberDuck

This cayenne has 45k miles on it. I need to look into the procedure for checking the fluid level myself.

cuttinsod

I had this same behavior on my 2011 CS.....complained to the dealer several times...hooked up the PIWIS...they couldn't find any issues....this went on over the course of 2+ years....most frustrating thing was when i took them out to show them, it wouldn't do it.....

Took it in for an oil change last month, and brought it up again to them...seems as though Porsche has issued a bulletin on this....they check the software, but it was up to date....but according to Porsche, it should be reinstalled again....as it turns out, the reinstall worked, and there was an additional fix for the trans programming.....

Ever since they reloaded the current SW, it has been smooth as silk.....perfect down shifting, and all of the jerky/inconsistent downshifting issues are gone...

AGARubberDuck

Awesome! I was going to file this in the "deal with it" bin. I'll take this info to my dealer as I have both the rev limiter issue as well as jerky downshifting, specifically in rush hour traffic.

Any chance you have the service info on that bulletin?

cuttinsod

i don't have the service bulletin, but here is a snapshot of the service record....the dealer was perplexed as to why this worked, but I would have them do the same for you....

cuttinsod

here the attachment...

deilenberger

If they update or reinstall the control software, stored "adaptations" are reset. Wonder if that's what cleared it up. The iCarScan has the ability to clear the transmission (and throttle and other) adaptations.

Just sayin'..