Paul, are you ready to recommend people look to the TPS as a fix? My car has only a mild hunt, but if that would clear it up, I'd like to go ahead and spend the $150-200(?) as a preventative before any serious wear/damage is done. Hopefully it's not too late.

I was looking through the classifieds and noticed another 98 A8 here in Raleigh, advertised as "Best Offer" and "needs rebuilt/replaced transmission". Is that anyone in here? If not, I'd like to pass along some of the D2 forum wisdom to that person, or at least try to make a few bucks fixing/flipping it...

 

I'm with ttulling on this one.

There is a system that is deficient. We may address weak links one by one to improve the situation. Wouldn't it be nice to have the full support of the operating parameters.

But, TozoM8 may have a good thing with the VB replacement. If you noticed the post I made on the many changes associated with the TCC of post DTE transmissions, there is evidence enough to think there could be an improvement contained within the later parts list.

But again. If it's hard parts, How can a change of any other part cause a temprary improvement? Something remains secret.

So, Call it $1k to replace the VB with an upgrade "just to see". What then?

We still have a TC and transmission with 100K + miles, and what if there are seals there with excessive leackage etc.

Additionally there may be fault with the variable output of the oil pump. That is really "outside" the autobox proper, and may only can be serviced with a transmission TC pull.

It would be expected that there are no hard parts failed if there are no other symptoms, but there have been many reports of the very last piston seal in the entire transmission failing with the result that reverse works, but little else (I may have this wrong but you get the point) Do a bunch of work and still some other little bit fall to pieces. The entire job is repeated again.

A total rebuild starts to sound prudent, IF it is a good one. (No rebuild includes every part! Which are replaced and which are reused is up to the rebuilder, Some may know VB's, some may not. NEw TC or rebuilt? Who has the skill?) Will a rebuild include the stuff that matters? (yet to be determined).

The first suggestion I will make for any car that hunts is to do a reset of the TCU and see if the hunting symptoms diminish, even temporarily. (50/50 warrantee?50 feet or fifty seconds?;-) Thus far, a reset has realized positive transmission performance for about a week on my car.

My next effort is to log the input signals that feed to the TCU as well as monitor the pressure solenoid control values before and after a reset. This will be a lot of data to sift through. 12 channels can be recorded at once with VAG=COM.
With the recent replacement of TPI, Spark Plugs and O2 sensors, I feel to be good to go. Time????

Step two of the effort will be to make a straight purchase and install of a contemporary Valve Body. New would be nice, but a qualified rebuild will suffice. I am working on this through an authorized ZF repair facility Although a specialist rebuilder has been helpful as well.

Presently, there is uncertainty about the compatibility of the electrical, and electronics of swaping units across transmission series and m.y. ZF doesn't recomend it, but have stopped supplying some parts associated with the older assemblies, substitution with newer P/N. (wiring harnesses, I am told).
TozoM8 may offer his experience on this.

IF the VB effects a long time cure, That is an easy swap. I want to do this myself, and wait for warmer weather to clear out the shop and not need to work with cold hands.

That's my present state.

CalG

 

Mine still hunts in 5th gear after shifting into it 5th at 42 MPH and then slowing to 39-40 MPH with very small amounts of throttle.

I keep remembering why I wanted an 03 S8.....to get a transmission that works properly.

 

We're in the process of acquiring a new vehicle for the wife. As part of that, I'm trying to figure out what I'm doing for my vehicle. Essentially the options are to keep my A8 and trade her truck on the new vehicle, or to sell (trade?) the A8 and have me take over her truck. All kinds of factors to sort through, like payments, payoffs, interest rates, and expected "repairs". Just trying to gather up all the pieces of the puzzle.

At this point I'm going to have to assume, for the sake of calculations, that I'll need transmission work in the next year or two- in the neighborhood of $1500-$4000.

 

but that should get you another 100,000 miles down the road!