RhinoComp

I have had a few instances in the past couple of months where I've had a lot of trouble getting going in the mornings when it's cold out (sub-40F temps). Typically the transmission seems to not want to lock the torque converter in these temps, I would assume it's to try to heat up the fluid. That's fine, and it's done that and seemed normal since I've owned my vehicle. However, these same conditions have given some very strange issues more recently and it seems to align with having my transmission fluid and filter changed about 15k miles ago (done by a very reputable shop in the Seattle area, Dobson Stuttgart).

On some cold mornings, I will back out of my driveway which is a somewhat steep incline and sometimes it will feel like I am "neutral dropping" it into first gear when I'm trying to slowly drive away. So I'm lightly pressing the gas, engine is revving but I'm not moving, and then it feels like it slams into gear and I can drive off okay. On mornings where it's at its worst, I will arrive at a stoplight or something far beyond my house and try to accelerate away, but am completely unable to because the engine is lugging, which is where I've noticed my transmission shows that it's in 6th gear... at idle.

My concern that I've had for awhile now is that these seem to correlate with what I've experienced in the past from an underfilled transmission, especially the feeling of it slamming into gear as I'm just trying to drive away slowly. But I also sometimes have to wonder about if this could be transfer case related since I'm at 113K miles on the original transfer case now, and these issues just so happened to become more frequent recently after doing my most recent 30K my transfer case fluid change (which strangely I've always had a couple of hard jerks the couple of days following a fluid change regardless of ambient temperature). But as soon as the transmission is up to temperature, it behaves and shifts flawlessly. Perfect shifts under power, and perfect driving manners aside from getting going after auto stop/start occasionally, but I don't think that's transmission related frankly. I personally feel like it seems that the issues go away once the fluid expands due to heat and is no longer "too low" which points towards low fluid, and the jerks also seem to point towards a potential TC issue, but adding into the equation the getting stuck in 6th gear with seemingly no way to get it out until it randomly decides to after 5-10 seconds has me stumped. What does the hive think in this situation?

Couple of other points that may or may not correlate, but it seems to occur more often when I park on my inclined driveway with the nose of the car pointed up versus pointing down (so gravity draining fluid away from the torque converter maybe?). I'm stumped y'all! But I do have a pressure fluid filler arriving this week, so I may at least try to do another drain and fill of the fluid myself soon. And I always park on this incline by engaging the parking brake in neutral, rolling onto the parking brake, and then shifting to park. So the jerkiness is not what someone would feel when parking on an incline and resting the weight of the vehicle on the "park gear" without the brake when shifting out of park to drive or reverse, etc. And there's no codes or anything associated with these conditions, and I have no seen the PSM light illuminate as if the car thought I was losing traction like some have reported it may do when the TC is slipping.

Surf SD

I posted basically the same issues a couple months back after being up at Mammoth for a few days with overnight temps close to 0. Not really any other replies like yours, so I hope we can figure it out together. This all started after a 80k mile transmission atf change. In normal temperatures I was initially ok, but the few days in Mammoth made me wonder wtf is going on. I took the CS back to my Indie and he verified everything was ok, but I continued to have occasional transmission surges that I never had previously. I took it to another Indie and he stated he found an old Porsche bulletin that mentioned similar transmission surges when overfilled, so he removed about 16 oz of transmission fluid. It did feel better (likely in my head) but it did occasionally still have a surge in normal temperatures.
The owner of the shop I have gone to forever called me up to discuss the issue and he thought it was the beginning signs of the Transfer Case failing. I have not noticed any of the other symptoms for a failing Transfer Case other than this new surge issue. I guess I will have to take it to the dealer for my next service and see what they recommend unless you discover a solution for us.
Regards, JW

RhinoComp

Overfilled... that is interesting. A few weeks ago I did actually try to see if I could add a bit and as I unscrewed the drain plug, fluid came gushing out even when far below 35C. So I had the thought that perhaps it could be overfilled, or maybe the green fluid level thingy wasn't screwed in far enough (or not at all). Wasn't going to risk either scenario unless I was ready to do another drain and fill to learn though. But I still have to imagine that since these issues are only occuring in the cold temperatures that it could only be underfilled if anything since I would imagine overfilled symptoms would primarily occur at operating temps.

My only thing that does still make me suspicious of the transfer case is just the coincidence of a few of these events following shortly after changing of the TC fluid. Just another reason I wish the 958.2 S was offered with a manual transmission!

garrett376

Why not just drive for a period of time with the transfer case unplugged to completely rule it out?

RhinoComp

I have considered doing that as well, but with temperatures warming up I don't think I would be able to actually rule it out since it doesn't happen frequently enough to reliably "force" the symptoms to be present. I mean we're talking maybe 3 or 4 times this has happened since December on a vehicle that gets driven 600+ miles per week. And the few times I have tried to perform the TC diagnosis procedure per the Porsche service bulletin (turning the wheels all the way to one side, aggressively mashing the throttle, trying to feel a clunk, etc) it's felt as close to perfect as I could imagine.

Doing more thinking though, it's an issue that has only ever been present when leaving my house where it will be parked nose up on an incline a lot of times and has never presented itself when leaving work where it is parked outside in the same cold temperatures 100% of the time, but always completely level. So I really just can't see it not being transmission/fluid related... or so I hope!

Surf SD

Guys is it easy to unplug the TC (like pull a fuse) so I can rule that out on my 2016 CS?

RhinoComp

Yes, I believe it is just this single plug here I circled.

Surf SD

Being that I think it is more of a cold weather issue, I am going to have to wait 10 months. My CS drove perfect yesterday.

garrett376

Not sure if it helps you, but transfer case performance due to clutch problems worsens when the transfer case and oil are hotter, not colder, while underfilled transmissions perform worse in the cold versus warmed up.

Surf SD

Garrett, what you're saying makes total sense to me, except an Indie in looking at my car stated they felt the surging gear/transmission issue was related to an overfilled transmission when I took it in for diagnosis. At my next service I was just going to have all the fluids changed (TC, transmission, etc) and pray that helps my issue. If that doesn't work then I guess I have to go to the stealership and see what they think.