audinutt

I haven't resolved it yet, but think I found some good information.

I really need to call in a favor with someone with a vagcom and a tip transmission

When i'm logging The engine fuel comsumption on the transmission measuring block 9-4 it's reading 0.00ms.

I have a hard time believing this is normal.

I swapped ECU's already to no avail.

Any ideas?
The engine is running like a top (no fault codes at all), the transmission does not exhibit the hunting while the trans computer shows it in warmup mode. The hunting starts once into regular mode.

Any help would be appreciated very much!

BTW, already did a filter change the other day hoping it would help (made no difference)

Thanks,
richard

CalG

Continuing on the pursuit of expert knowledge on the topic of uncontrolled TCC release (hunting) I did come across a reference in the ZF service and rebuilding profession. The suggestions received were simple, and this reference sounded confident (I will hold back the identity lest this be just another red herring).

The suggestions:

1) "Set the Trans to "European mode"
Presently, this trans is coded 00001 RoW. I may try the sport mode someday.

2) "Go over the grounds in the passenger foot well." Friday evening I took a look at the fuses and relays and the ground studs on the e-box in the right footwell. (I wish I would have read the TSB to service the ground studs located above the fuse panel. Oh well another trip in there with Stabilant or DeoxIT is in the planning)

3) "Unplug the TCM let it sit, then "cold boot"

Actually the words given were "disconnect the battery and tie the terminals together for 12 hours"
This bit of instruction. is a bit vague I feel, but the idea can be appreciated. These TCUs have a "learning" feature that may be best to clear. I disconnected th TCU in the plenum under the hood right side for about 15 minutes while I disconnected and re made every other connection in that box.

4) "Drive it like you stole it!" This to put in a new "learning routine" I am sure.

The bottom line is "Poor connections and grounds make it hard for the controler to make up it's mind about how to process light throttle conditions. The controler "hunts" for a solution. The symptoms ar just blind obedience to the commands that are generated due to poor quality inputs.

My results? After doing the operations listed above, (the drive it like you stole it" was th best part ;-)) This A8 behaves much differently. There is some "hunting" under some conditions, but much reduced frequency of ocurance and diminished amplitude of fluctuation. There is now some lock-up and unlocking of the TCC "harshness" that I had not noticed previously But, the shift points have moved up the RPM scale. (relearing?)
The transmission response and Hunting has been entirely "rearranged". I am convinced that we have electrical situation that can be improved.

What next?. Well, I'm off to radio shack to see if they have DeoxIT and then I will go through all the connectors and ground studs in the right side foot well again. Included in the service will be the multi pin connector for the VB solenoids. ( front of the transmission pan).

I wish I knew how to read the wiring schemes to better know where all the connectors are located on the car. I would be sure to service all the electrical connections.

Now, Why do I think the electrical gremlins are worth pursueing.
Water coming into that area from plugged drains!
This car was soaking. I have the floor mat out and hanging next to the wood stove drying right now. I have set the passenger side climate control to 28 degrees C and the air control down to dry that area.

VAG shows that the slip is associated with transient current changes to the TCC.

The TCU has a learning mode that must be easily confused.
I wish to know precisely what the differing codings do to the TCU and it's learning process. That may be the part that Audi does not care to admit, for I am to understand that control modules are expensive to reproduce. (custom circuitry) The AUDIWORLD pages on coding the transmission are subjective, and my own experience differs, but admittedly is to little to be definative.

What I am cautious of? That clearing the TCU may just restart the learning process, and the condition will return every few days. (That is not an acceptable solution , but has been proposed on this forum.

Well, Enough writing for one post,I am very upbeat on the notion that we are getting MUCH closer!

Sorry, Nothing on the thump yet. That may be a spring in the VB. {:-(

More to follow I am sure,


CalG

rompbogger123

i also feel that there must be an answer for this. but i can definitely say my hunting is gone after coding it to 00012. but i am sure that this thump we all encounter is related to the hunting. it must be in the valve body or the torque coverter programming etc..