Malc_UK

Hi co-owners. I've owned my '97 A8 4.2Q Spt for one year, and prior to purchasing thoroughly reseached the possible pit-falls of runnning one. So I knew what to look for when buying. The obvious 'weakness' being the transmission! I final found my total Audi Dealer serviced example with NO discernible faults. Taking notice of the nunerous horror stories regarding transmission failures I quickly changed the trans fluid & filter at a not insignificant (using Audi ATF) cost.

12,000 miles of fabulous driving later, my transmission isn't playing ball;

Upon coming to a stop after driving in TipTronic mode the autobox wouldn't select 1st or 2nd drive gears. When trying to `pull away' in `D' the revs rise briefly then the autobox goes into `SAFE' mode and selects 3rd gear with a big kick, which I believe is due to the suddenly realised line pressure.
Prior to this event, I did experience one irregularity with the transmission when towing a heavy load (approx 1750kg of braked trailer). When slowing, coming down the gears the transmission occasionally selected 2nd, 1st and `N' with an uncharacteristically large `kick'. However, there has been no repetition of this during normal driving.

The car is driveable if coaxed slowly away in third (I believe its default gear??), then it will change up to 4th and 5th when needed. However, the TipTronic (manual override) does not operate. I limped the car to a Transmissions Specialist.

I loaned the Trans Repairers my VAG-COM enabled laptop to help identify the cause. The results thus far are;
· The car starts in normal autobox mode, selects `Reverse' OK, but upon moving the lever into `N' or any of the `D' (drive positions) the reading from Measuring Block 002, No 4 (Engaged Gear) reads `m1'. Unfortunately, we don't know what this means. However, the gear lever position sensor (Measuring Block 001, Reading No 1 corresponds correctly with the position the lever is in. This leads us to believe that there is a poss. ECU or electronic problem???

· The following fault is recorded: 17114 - Incorrect Gear Ratio P0730

Which Audi (BentleyCD) diagnoses as either;
1. Sender for transmission output RPM (G195) faulty. - We've replaced this but no change.
2. ATF-level not OK or ATF contaminated. - Checked and all OK (only 12K old).
3. Clutch slipping/faulty or solenoid valve dirty/faulty. - Possible, but want to know what 'm1' mentioned earlier means, before embarking on the cost of box removal?

We have also disconnected the battery and cleaned the autobox ECU connections, checking there hasn't been any water ingress. No change.

Finally, I'm also awaiting a response from ZF UK who have referred the query to their German counterparts. And rather interestingly, one of their Technicians mentioned that the A8's 'Air Mass Meter' can, if faulty (which is common) contribute to transmission problems, ie incorrectly input info (engine load settings, etc) which causes inappropriate gear selections. Hummm? However, having previously working in the trade for 17 years I am reasonably astute to any defects and am confident I would have noticed such abnormalities.

Wow, what a monolog!

I would welcome any knowledgable input on this issue as my gut feeling is that it's electronic, not mechanical - famous last words! Cheers.

PaulW

TozoA8 had EXACTLY the same symptoms as you did with his 97......he came to my house 3 times and we troubleshot the heck out of it.....and he did this 2X over at his place, running jumpers etc.

In the end, it was one of the three clutches that was toast.

If you can put it in reverse and it hooks up just fine and powers the car normally, it's your clutch.

There are three wet clutches in the tranny, just like a motorcycle clutch.

You can get the tranny rebuilt with new clutch plates, it would fix it.

Check your email, I may have another solution for you.

pw

Malc_UK

Thanks Paul. Knowledge (experience) is a wonderful thing. You seem very confident. Is there anything else I need to do to make doubly sure?
Malc

PaulW

TozoA8 should chime in anytime tonight....maybe he'll have pictures of the failed clutch plates

tozoM8

Paul is right, I had the EXACTLY same thing. You have lost the fluid pressure in the tranny. DO NOT drive the car! Have them to check out the valve body. The main problem with our tranny is the valve body and the TCU. Mine had a cracked part in it,( yours sound like the same )
<img src="http://pictureposter.audiworld.com/80919/dscn1035.jpg">
<img src="http://pictureposter.audiworld.com/80919/dscn1069.jpg">
<img src="http://pictureposter.audiworld.com/80919/dscn1070.jpg">
<img src="http://pictureposter.audiworld.com/80919/dscn1290.jpg">
but all that jerking comes from the TCU. After the tranny rebuild it felt like you are on the rodeo. Lots of jumping hesitating. After 2-3 days it started to learn my driving behavior and after a week it is much better. I drove it too far after the crack, but I believe yours is fixable if you did not drive it too much. It is worth to try to fix it because it can be done fast and cheap.

Mitaka

Scary stuff

Malc_UK

I'll instruct my trans specialist and keep you updated, hopefully with pics.
Apart from the 3 clutches and the obvious, is there anything you would recommend we replace, ie solenoids or the Air Mass Meter, etc?

I can't help thinking that towing my mates 40 (hopefully pic uploaded - he's the one still smiling) contributed greatly to the failure - the tranny really didn't like it. And I never got to drive his 40!!

Malc_UK

<center><img src="http://pictureposter.audiworld.com/84760/towing_the_40.jpg"></center><p>My friend (GTD40 owner, foreground) and my son (background)

ryoung

GT40 !!

<img src="http://www.gtd40club.co.uk/images/FOS2003/DSCN1598.JPG">

PaulW

Hey, at least you were towing a GT40!!!!

Latest standard question when somebody's car goes into limp mode: Have you been towing anything with your A8/S8 that weighs more than 2,000 lbs with trailer???

Heck, it could of been your mother-in-law's furniture 'cause she was moving in your house!!! At least you have this picture!!!! ;-)