Gr8White

I bit the bullet a couple of weeks ago and bought a 99' 4.2 Quattro that had a suspected bad transmission. My 12 year-old dream come true! Thanks to this forum and http://www.audipages.com/Tech_Articl...servicing.html, I decided to pull the tranny pan and replace the filter and fluids. To anyone with a suspected bad ZF transmission, please start here!!! It's better to throw away $200 and find out you do need a several thousand dollar transmission job than to get a several thousand dollar transmission job when $200 would have fixed it.

The transmission now shifts like silk, but I'm having a nagging issue where the torque converter locks and unlocks randomly, mainly at part throttle in a tall gear or when letting off the gas from freeway speeds. With Ross Tech VDS, I am able to see the stall speed drop to zero as the cars RPMs drop slightly.

I realize that this issue has been beat to death but I have yet to find some methodical troubleshooting procedure that would allow any of us to isolate what is precisely causing this type of headache. From what I've seen, there are some great minds on here; surely, someone has such a procedure???

I truly look forward to the day when I can take someone for a ride without them asking about the up and down surging is as the torque converter locks and unlocks or the little jolt that occurs when getting off of the freeway.

TerminA8r

There is a fix to the TC drop out problem.

Scroll down about 1/3 of the page.
https://www.audiworld.com/forums/sho...php?p=15613320

Gr8White

I did see this post when I first started researching the thump problem. For me, there were too many opinions on what causes the converter to lock and unlock. I was hoping that someone had some troubleshooting procedure that would methodically zero in on what was causing these transmission problems for us.

I will make some time and follow the procedure outlined in that post though; it's certainly worth the shot. Thanks for reminding me of this post.

It may also be worth mentioning that when I was using the Ross Tech software, the amperage for the torque converter did not appear to change when the converter would spontaneously lock. It was usually stay in the 0.5 ish amp range, even when the stall speed would drop to 0. Is the refresh rate of the software just too slow to show the related spike in amperage associated with the spontaneous lock/unlock? When the converter status would go to and stay locked, the amperage would be around 0.744 amps.

I'm curious as to other peoples experiences with this adjustment.

Have any of you followed the procedure?
Has it resolved the thump?
Miles on the adjustment?

TerminA8r

Yes
Yes
About 7-10k (car was hit and totaled)

I did this mod on my 99 A8 at around 110k. TC never dropped out again. http://forums.quattroworld.com/a8/msgs/17301.phtml
There is a downside in teori however, "if you hit the brake hard (emergency situation) the engine could stall and the car will become hard to maneuver."
That never happened to me, however, I belive it to be true.

Cj7

Its the vb

Get your vb bored or replaced

http://www.freddiestransmissions.com...alve_body.html

Gr8White

I'm not going to say that the problem does not lie within the valve body, even though the quality of the individual shifts are near-flawless. My reason for this post was to see if anyone has a diagnostic tree that could isolate specific problems within the ZF transmission.

With all of the reading and digging I have done, it seems that people just start throwing parts at these problems. On one of the forums, I even read of a rebuild that failed to cure the problem, suggesting that the problem was external.

I don't want to be that guy throwing parts at problems. For now, until I find such a diagnostic tree, I'm going to follow TerminA8r's advice and turn the adjustment slightly up on the EDS4 regulator.

igotav8

My feeling on this is a lot of the problem lies in the tcu programing. Unsure how you would fix but if they can remap the tcu to change all the shift perameters on my chevy truck their must be a way to do it on this car. I can put this many miles on a gm transmission without the valve body wearing out in it. Why not this one. Any ideas on reprogramming?

Pchelka01

Have tried that, replaced with numerous TCUs and drove on them for a few weeks each, giving each one time for any adjustments.
Nothing happened.

igotav8

What I mean is the tcu needs remapping. The programing is defective not the tcu.

Gr8White

So how does one:

1. Determine if the TCU needs remapping
2. Go about remapping

Ross-Tech??? Dealer only??? Did it work for you?