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

JasonAndreas

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.

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.

flatsixx

JasonAndreas,

Thank you very much for your help . I found TSB:3701 on rennTech and I believe it is the problem. Now, the hard part is the deal with my dealer. My car ran out of warranty a year ago and I'm sure it will be such a pain to get them covered for the problem.

Anyway, Thanks again

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.

Ji H. Jung

Hello there~




I assume that I have same issue on my 996TT, Did you solve the problem by updating a TCU module??

Timothy Kee

I had the same grinding noise. I just avoid accelerating in high gear by shifting down. Problem solved.

cdk4219

Thanks for replying to a 13 year old thread with a fix to avoid the grinding by not accelerating in high gear. If your wipers stop working it can be fixed by moving to the desert.

Timothy Kee

The noise is only apparent if the box is push from below ~2200rpm to accelerate. I think it is reasonable to shift down a gear to get better acceration and avoid putting excessive load on the engine.