Hard Upshift During Acceleration: HELP!
 

Last week during a spirited drive, my 2005 CTT cated up. For the first time she was "exploding" into higher gears. She felt like she was slipping then slammed into the next gear.

This only happens under hard acceleration at some speed--not as much as I am the SUV are used to.

When I went to passing, she down shifted properly.

However, during the last event I saw her creep past redline and shift hard at ~6,600.

Technician plugged in and we found no error codes.

I have ~92,500 miles and under warranty until the end of August. The problem is I am about to tow a small trailer down the Alcan Highway to puck up a rather large Travel Trailer in early August.

Indeed, I need to sort thos out before I get on the highway. Any and all ideas on what I should be looking for shall be appreciated greatly!

Thanks!

Sounds very odd. Love how inconsistent these issues can be. Sounds like it might be something with your tranny controller.

BTW - you have an extended warranty? Porsche?

Yes, I still have the Porsche CPO Warranty.

I repeated this enough during that road trip that after half a dozen HARD upshifts, I don't want to do it again. Besides, that young State Trooper was very nice in giving me a warning. I don't think I can replicate this under legal speed limits. Must be >70

While the computer analysis came up completely clean, I have an appointment with the dealer and I have an appointment with the independent (and far more experienced Porsche mechanic) to pull transmission and differential service as well as brakes and coolant hoses. I am hoping the "160,000 mile service" may reveal the culprit and/or take care of it.

I remeber your problem, though.

Yeah - I hope you are not heading the way I did. My tranny shifted perfect right up until I dropped it at the mechanic.

One of the issues they told me that they found oil had somehow crawled up the cable sheath to the tranny brain and could have shorted that out in due time as well.

Fingers crossed.

IS there anything I should tip the mechanics to look for?

I had this same issue in my 2004 CTT, ended up replacing the valve body on the transmission which fixed the issue. About $1500 installed if I remember correctly.

My issues started with a small leak and then we found the tranny issues. They only found the tranny oily brain issue after they pulled it apart. Valve body sounds interesting.

Reborn, Was it slamming into gear like mine?

With the power of this engine, those are downright scarey shifts.

Yep, sometimes so hard it felt like the transmission fell out! LOL

It was mostly on the 5-6 gear change for mine but I have heard it can happen on others too. I believe there was a TSB for the control unit for harsh shifting as well (TSB #3730) and mine was replaced along with the valve body. The dealer said something about the new valve body requiring a matching controller to go with it.

FYI, because it was a mechanical/hydraulic issue with the valve body there were no DTC codes on mine either.

sounds like a valve body issue. With your mileage, I'm pretty sure thats it.

I have a similar probe on mine. Very intermittent (mostly when hot or on the why for more htan 20 mins) if Im in 6th and floor it, my 3rd to 4th shift is brutal! The whole car bucks and it almost feels like the trans is going to explode.

Apparently, the cost of the valve bodies have come down. In Canada, you can pick one up for around $1400 + oil & gasket. THe parts guy also recommended an new trans ECU but I have a friend who's a mechanic at the local dealer and he said it was not necessary.

I've been waiting until mine gets worse before spending the $$$

Is your traction control turned off when this is happening?

Transmission hydraulic valve body sounds suspect. They have been known to have faulty solenoids inside them causing the hard shifting.

Sounds like the solenoid is faulty requireing the entir vale body to be replaced. 3rd to 4th gear shifts are BRUTAL. This occurs with the PSM on. It is a recent development and I don't want to experiment with it much least I risk more damage. I am lucky--this is under warranty.

CTTinT--I printed your message and am taking into the dealer on Tuesday. Thanks for the tips, y'all.

I just brought my 2006 s to an independent for th same issue.. no error codes were found but it hasn't happened since I brought it there, its very intermitten, but fels/sounds horrble when. It does happen.