Had my car for over a year. Never experienced anything strange with the torque converter. Note: 2 weeks ago I replaced the suspension with Koni FSD. Drove the car hundred miles or so since suspension, all good. Then out of nowhere the car developed a VERY noticeable hesitation when accelerating n 2nd gear @~2300rpm. It NEVER had this before, and I have driven 10,000miles on the car. Even worse, when stopping at a light, the car has a minor shake as the torque converter disengages. I had my indy check trans fluid, they said its at the proper level. They suggested replacing the trans fluid and filter. Car has 68k miles. Is this normal and I never noticed it with my former dead suspension?

 

Seems to be issue as described here TSB: 6/02 - 3701
As per TSB, I drove the car in 2hour stop and go traffic. Going to have my indy reset the learned values in the TCU...

https://rennlist.com/forums/996-turb...tiptronic.html

"Its a well known problem and the "fix" is to install a new Tiptronic control unit with modified software. The newer control module has the part number 996.618.180.04 (or greater). I just noticed that you have a 996 C4S and not a turbo so you want a control unit with the part number 996.618.180.07 or newer. Have your dealer look at the Technical service bulletin 6/02 - 3701, dated February 14, 2003".


More helpful info for anyone else hitting this:
There is a TSB about a problem that sounds similar to what you have described. The symptoms include, inter alia, a hesitation/stutter in second gear (in the 2-3000 rpm range) and a grinding sound at very low rpms (e.g., below 1700) in third gear. The problem is generally intermittent and caused by stop and go driving. The Tip ECU defaults to an inappropriate program to accomodate the stop and go driving. As stated, the problem is intermittent, and may not occur for many months and extended stop and go driving. The problem can be temporarily remedied by extended highway driving, which causes the Tip ECU to revert back to its normal program. The fix is a new Tip ECU (the dealer will replace the ECU under warranty).

Try the following: find an open highway (minimal traffic) and drive 20+ mins at 70+ mph without stopping or slowing. If the problem goes away, it is likely the issue addressed by the TSB.

Also try starting in first gear, and running the rpms up to 5500+ before shifting to second, such that you are above the stutter/hesitation range (2-3000 rpms) upon hitting second gear. If you don't experience the stutter, it is likely the TSB problem.

Finally, the TSB stutter/hesitation problem only occurs after starting from a full stop, as opposed to reducing your rpms while in motion. Thus, try driving in second gear and, after the first hesitation/stutter, drop your rpms back down and go back through the stutter/hesitation range. If you don't experience the stutter/hesitation on the second pass through 2-3000 rpms in second gear, it is likely the TSB problem.

If you have the TSB problem, have your dealer order a new Tip ECU.

"The reason for this is the adaptation of the torque converter lockup clutch in the Tiptronic control unit. If the 996TT is driven in a restrained manner or is frequently driven in stop-and-go traffic, the Tiptronic control module adapts itself to unfavourable values that cause the grinding/rattling noises."

 

 

Yeah. Car is gonna get full trans service by my indy next week (which they confirmed they also reset the adaptive learned values as part of procedure). But glad to find out ahead of time that would not have fixed the issue. I might have to seriously investigate sourcing an updated TCU as I do lots of stop and go traffic driving, or buy a durametric so I can reset the TCU myself. I am hoping the reset makes the problem go away for a long time, as I have had the car 16months and this is the first time it happened. Anyone know what exactly I have to buy to reset the TCU adaptive values myself?

 

 

I don't have a TT, but my 03 with Tip gets a little confused on the shifting in extended stop and go. My solution, I put it in M and shift it manually. Never had any grinding or shudder, just a hard shift.

I also did the "reset" thing where you hold the throttle down and that cleared up a lot of wonkiness when I first bought it.

 

..dup

 

I don't have a turbo either, but it apparently affects TIPs in both MY 01 and part of 02. I only drive in "M" mode as well, but my 2nd gear is acting exactly as described above. The actual shifting is flawless. Its all the torque converter engagement where you can feel the notchiness. Really the only part that is bothersome is stopping while in 2nd.

What are the steps you did to reset? Even though I believe that only rests the ECU learning, and not the TIP TCU.

 

For anyone interested, or people who hit the issue in the future.

Well some good news.... For the hell of it, I stopped at my local dealer and asked them to reset the TCU. They said they did not have time today to do it... They did print out the full TSB for me and quoted me the TCU replacement! <Expected sticker shock>. So I followed the TSB, and drove the car on a highway in a "sporty manner" for about 50miles. Speeds avg 80 and alot of full throttle acceleration, hitting all shift points. The Tiptronic TCU computer seems to have learned "good" adapt values. So far the problem is completely gone. I restarted the car since and drove and all is well. Test will be tomorrow when I cold start it and make sure problem is gone (till next time I get stuck in 3hours of traffic and TCU learns bad behavior again). Might try to hunt a used updated TCU (Part 996.618.180.07) and have my indy install.

 

Year later update, incase thiis helps anyone else.. Problem came back. I purchased a Durametric and was able to in 30secs reset the adaptive values of the TCU. Drove off right after and the problem was completely gone. I drove the car up the highway in AUTO mode, letting it shift thought all the shift points. Letting the car idle for 10mins to write out new values to the TCU. I would be very happy if I can fix this without having to drive the car "SPORTY" as Porsche states for 75miles.

 

Porsche service manual page 5611 says Tip holds 9.5 liters of fluid, and change quantity is approximately 4, so more than half of old fluid still there. If that is correct you should only be charged for 4, and I would ask what brand was put in so won't be mixing fluids next time.

Our '02 Tip I never notice the torque converter engage. In old '06 Jag XJ the engage/disengage was very noticeable, acceleration on freeway was slow until disengaged. Our 911 at freeway push gas and it straight goes zero waiting. Computer says 21.6 mpg average mostly freeway.

I believe in older vehicles with locking torque converters there was an external wire to the transmission. If ours has that a switch could be put in line to disable the torque converter when desired.

 

I never got the fluid changed. I had an amazing indy where I used to live, but I am not sure who to trust locally with that job. Was debating taking it to a dealer for the trans service. Normally I do not notice the engagement, but if you have the bad TCU part number.... and it adapts bad values....you sure will know it! It almost adds an extra "shift" in 2nd gear, and jerks the car forward as to come to a stop. Lucky it appears easy to reset the problem away with a Durametric. The updated TCU installed was quoted ~$2200 from a dealer.

 

Yeah Shawn, thank you very much! My '02 Tip is exhibiting what appears to be the same problem. Accelerating in 2nd gear from a stop often has a "thunk" sound and hesitation just like this thread describes. And about once week I do hear some grinding sound that is very concerning and very hard to associate with anything. It's a daily driver, and I have stop-n-go regularly. I suspected a loose control arm, but really it feels like slop in the drivetrain. Since it is inconsistent, clearly the torque converter seems like the right place to look.

And buying the Durametric for about $300 sounds like the right path, since would confirm the root cause, and then I can use it for other things as well.

Thanks, reading this thread and the embedded link to another Rennlist thread on the same subject is providing some very good leads and hope.

 

The tell tale sign is it feeling like its still connected pushing you forward as you are coming to a complete stop. You FEEL and hear the disengage. The car will also feel like it has a 2nd shift occuring while in 2nd gear around ~2800ish rpm. If you let the RPMs get very low in 3rd it will actually make a grinding sound (cannot imagine this is good for trans). I just took the first long "sporty" drive since my quick durametric reset and idle. It feels like I have a whole new transmission.....clearly the TCU settings have never been right since I bought it, but twice in 2.5yrs it got bad. I drove it to "not so bad" setttings...but not GOOD settings like now. The car shift SOOO smooth now in all gears, up and downshifting. Very happy and wish I knew this last year when it first started going bad. Good luck, hope it helps you! Any questions let me know. I have talked to two other 02 TIP owners on FB who have had same exact issue.

Stop and go traffic seems to def be what causes the microcode bug to start. First time was ~2 hours of stop and go that did it. Second time it was only about 20mins....

 

Here is the TSB my dealer printed out.

I like how Porsche blames the customer for hitting stop and go traffic and driving the car in a comfortable manner....LOL!