flatsixx

I have a 2002 C4S with tiptronic. Sometimes, in 3rd(manual mode) at 20-30 mph if I try to accelerate there's a grinding noise under the car. Also when it's in auto mode with slow cruising speed - again at 20-30 mph(still in 5th)and I give it a little gas. There's again a grinding noise from under the car. Should it stay in 5th in such a low speed??

The problem started back in 2002 when it had less than 600 miles. The dealer changed transmission flulid and the problem seem to be solved. Now at only 3,500 miles, here it is again.

The Porsche dealer is having trouble fixing this. Has anyone seen this problem, so that I can give the Porsche dealer a pointer?

Shin

djantlive

If the car still under warranty? Does the tranny have any fault code? Is it on the latest software.

If under warantee, it may be a good time to get a new tranny. Auto tranny is very complicated. I'd have the ATF drained again to see if you get metal particles. If so, the tranny may need a rebuild and replaced. Have the ATF filter changed too.

At such low mileage, esp given past repair, the tranny should be replaced if dealer can't figure out what's wrong with it. Even if your warranty expired, I'd think PCNA should cover you. Once fixed, drive it more often to make sure you don't have the issue again.

Nicolaasdb

give your Porsche dealer this pointer: stop trying to fix it!! and replace it with a new transmission!!!
You have to tell them what to do, because if you are nice they will take advantage of it!!

JasonAndreas

See my post in this thread.

kent

hello guys, i found my car has this problem once a few days ago, so how i can get my car to fix? going to the dealer or any good indy shop ? thanks in advance.

Pac996

20-30 in 5th NOT NO BUT HECK NO. I think something is goofy. Should be down shifting into at least 3rd when creeping down past 30. I think mine even if still in manual mode forgetting I'm there or it got bumped there will automaticly downshift. At least that's what I've noticed. Maybe my shifting map is just all chocked full of yah downshift to keep around 1.5-2k but I still think 5th at 20-30phm means somethings wrong.

Graufuchs

My tip dumps out of 5th I believe at 45....definatly glugging around...you need a software update or start manually downshifting when you start slowing to avoid this.

Torontoworker

The grinding noise is what is the worry here - shifting into 5th at such a low speed may just be another symptom on top of a lot larger problem. Could be a torque converter issue?? There should be a code coming up if it is but may it might not be a 'display' code that a CELL get's turned on for. I'd really be hesitant to drive this car in this condition. I would be flat bedding the car to the dealer and getting this resolved for good. Coming in under it's own power doesn't get their attention as much as a flat tow at their expense under warranty. If you keep driving it this way trying to figure out what is wrong they will try to nail you with the 'you made it worse by driving it' excuse.

TCR

I have some bad news for you here; the trans needs to be replaced. I just had mine replaced because of a whining noise with a "new" tip at the local dealer. After waiting for over a week for the "new" transmission to arrive, I finally got my car back. After driving for about 100 miles, I began to hear the grinding noise of which you speak. Specifically, if I was going up hill in 2nd gear, and shifted into 3rd before winding the engine up in RPM's, the grinding noise was very apparent. The grinding appeared to happen just as the torque converter was locking up as it should.

I returned the car to the dealer who found that the front shaft in the "new" transmission had excessive play and was the cause of the issue. A second trans was ordered and arrived from Germany 1.5 weeks later. The second new trans appears to have resolved the issue.

The dealer claimed to have never heard of this issue before, but it certainly seems to be a similar issue. The trans is about a $12,000 replacement cost and can't be repaired in the field.

PM me and I will send you my phone number if you would like to discuss any further.

Tim

kent

Thanks Tim for your response, I got confuse now, from another pose, it states as follow------------
Quote:
Originally Posted by flatsixx
I have a 2002 C4S with tiptronic. Sometimes, in 3rd(manual mode) at 20-30 mph if I try to accelerate there's a grinding noise under the car. Also when it's in auto mode with slow cruising speed - again at 20-30 mph(still in 5th)and I give it a little gas. There's again a grinding noise from under the car. Should it stay in 5th in such a low speed??

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.


Quote:
Originally Posted by flatsixx
The Porsche dealer is having trouble fixing this. Has anyone seen this problem, so that I can give the Porsche dealer a pointer?

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. With the TSB and prior (wrong) attempt at fixing the problem you should be covered under warranty.

roadsession

I know I am resurrecting an old thread but because NO ONE seems to have posted a resolution here it is:

I had this exact same problem start last week - that's right : about 600 miles after my new engine replacement.

I feared that my transmission was toast after scanning this forum.

Well, the problem turns out to be bad adaptation values that the transmission learned from my feathering the car during the break-in period. There is a TSB that calls for the replacement of the transmission TCU - which is about a $1,600 part.

So I decided to simply reset the transmission adaptation values and then drive aggressively. ALL NOISES and slippage/grinding noises ARE GONE.

318touring

How do you reset the trans?

roadsession

I had the dealer use his PIWIS

Pac996

Won't disconnecting the battery for a period of time reset?

nizzki

I just got my 996TT and it hasn't had this TSB applied.

Roadsession, do you have to keep resetting the TCU often so it doesn't re-adapt to the crappy settings, or do you just drive it more aggressively now?

Also, can someone send me the full TSB text? I'm curious if it's potentially damaging to the transmission, or just sounds godawful.

Oh, and does disconnecting the battery reset the TCU as well?