allroaddave

Car is a 2004 Allroad with 61K, tiptronic and no issues the whole time we've owned it, always serviced at the dealer.

We were on a trip to Colorado, from KC, on the way home way out in western Ks on a smooth backroad, doing about 65 on the cruise control, all of a sudden it was like I hit something in the road (which I didn't) and I noticed the tach was at about 3500 instead of the 2800 or so it had been. Within a few seconds all was normal again, and it didn't do anything wrong the rest of the way home.

One week later, my wife is driving in town at about 45 and it did it again, no cruise control this time.

Ruh-roh........

We've had no reverse engagement issues, in fact none of the issues that seem to normally crop up with these automatics whatsoever.

So, rather than just pull it and buy a new remanufactured trans, I'm wondering if I could have a valve body problem, or an electronics problem or...??????

As far as I know the tranny has never been touched, unless it's done under the "free" routine maintenance program in the first 50K miles.

Any ideas?

No codes are stored.

amiram

Did you replaced the automatic transmission fluid and filter? Check the condition of the oil. And its level. It sounds like the TCC problem. At first no fault codes.

allroaddave

TCC problem?

I don't know why guys on forums assume everyone will know what their acronym means......

Fluid is full, it's a bit of a procedure to check it .... you have to have the fluid temp between 80 & 104*, then take out a plug and let it leak - what a ridiculous way to have to check the fluid - why not a simple damn dipstick?

But I digress.......

As I said before, we've had no reverse issues, and my understanding of the most common problem these have shows up as a reverse issue first. I can't see either low or old fluid as causing this particular problem, and since it's only happened once to me and took me by surprise, I'm not sure exactly what happened. Plus we drove it another 500 miles after it did it with no further incident.

To me it was almost as it we'd hit something, it was a very sudden and harsh event, same with the wife only she thinks that since she was only going about 45 the severity was much less for her than when it happened on the highway.

I wonder if I could have an electronic issue instead, but with no codes I don't know how to check it.

Anyone in the KC area with a VAG-COM that we might hook up?

We're going to swap cars for the short term so she won't get stranded coming home from her work at 2 am, and I'll see if it does it again.

GTA_Driver

If your RPMs spiked after the "boom", sounds like the torque converter isn't locking up, or maybe the at dropped a gear down.

Old fluid when dirty with metal shavings can interfere with the operation of the valve body, and you could experience any number of issues.

I would first obtain VCDS and scan the car for codes, specifically the transmission control unit. If no codes show up, try measuring blocks and see what's going on with the TC.

Finally, consider changing transmission fluid and filter. Your tranny could have leaked some oil out and the level could be too low.

G0to60

I had something like this happen to me on two occasions. Just like you said where it seemed that I hit something or it downshifted quickly and then back. It turned out that anytime this happened I had my bluetooth OBD (On Board Diagnostic) scanner attached to run the Torque app on my phone. I verified this by doing it in my driveway and slowly down my street. When I unplugged the scanner things were great but when I plugged it back in it would lurch every once in a while.

Now, I'm not saying that this is your problem but it may be something electrical similar to the scanner screwing up something.

After all of this I replaced the fluid and filter for piece of mind. It's not too difficult and good preventative maintenance.

amiram

Just update: the TCC indeed locked up, but in a BIG Bang because the surface friction does not exist anymore. Then iron on iron friction Gives you a Bang, from there the metal chips that penetrate the block valves.It cost me Two years ago about 350 dollars. $ 100 to refurbish the TCC and other pay for work. You waiting for two hours and get the refurbish TCC. If you still do not know, tha TCC is the torque converter clutch. It's his job to prevent slipping in the torque converter by lock him up.Each up or down shift.Except first gear and reverse gear

allroaddave

Interesting thought.....I did have a Garmin Bluetooth dongle plugged into the OBDII port to give my Garmin unit info to run the gauges....I have this plugged into my MINI all the time, but put it in the Audi for this trip, I took it out the other night and haven't driven it since, and it was in the car when the wife drove it too. My understanding of these units is that they are passive, read-only units, but I suppose one could develop a glitch that could affect the car. Why it only did it twice over a 2,000 mile plus trip is still a mystery, but it does give me something to look at.

I think my next move is to drive it some more and see if it does it again, so I can get a better description of what happens.

Thanks for the tip, goto60.

amiram, I'm not discounting what you're saying, but it just didn't feel like a torque converter lockup/unlock situation, but since it only happened once to me so far, I don't have enough info to make an informed decision yet.

allroaddave

Update:

Well, so far I've driven it a few hundred miles under all sorts of conditions and it hasn't put a wheel wrong, same as always.

I'm beginning to think that GoTo60 might be onto something, but I'm not brave enough to plug the Garmin Bluetooth module back in to see if it causes mischief - besides, it took close to 1500 miles the first time before it acted up.

The wife seems confident enough that she's started taking it to work again (she works nights) so, we'll see....

I still wish I could find someone local with a VAG-Com so I could look at it in depth......

I am planning to change the fluid tho, just as a matter of course.

G0to60

You might try some low speed tests. I did one test on the street in front of my house at just enough speed for the trans to shift. First I drove down the street with the OBD scanner unplugged. Drove down and back. Turned off the car and repeated with the scanner plugged in. I could feel a slight lurch when it shifted into second but at these low speeds it wasn't as drastic as it was on the highway.

jjrichar

Here's my take on what has happened.

If there was a loud thump and jolt when this happened, this tells me that it's not from the torque converter clutch disengaging. If it disengages, it's just going to allow a smooth increase of RPM, and not create a jolt. Also, the increase in RPM you talk about seems too much for just the TCC unlocking.

I think the transmission has momentarily gone into limp mode, which just shoves it into 4th gear. The transmission normally uses electronics to control the solenoids that change gears. Because of the electronics involved, this makes the changes nice and smooth. If this system fails, there is the manual valve on the side of the valve body that can put the transmission into either P, R, or 4th, depending on the gear lever position. It bypasses all of the electronics and most of the valve body, and for this reason the change is very abrupt. In this case because you were probably in D, it has just shoved it into 4th, and due to the abrupt nature of the change, it feels like you've hit something. I've had our transmission go into limp mode before, and just selecting R or D from a standstill feels like you've been hit from behind.

Why has it gone into limp mode? Could be any number of reasons, but the first things to do are what you are doing. Change the fluid (don't just check the level and top up), but most importantly get a copy of VAG-COM and read the codes. They will tell you what is going on. If the fluid level is correct, it's most likely an intermittent electrical fault. Only the error codes will tell you this.

Prior to fixing the problem, my advice is to not drive the car too fast, as it dropping into 4th quickly is going to put a lot of strain on the drivetrain. It makes sense to me that when it happened to your wife at slower speed, the feeling inside the car was less abrupt.

The problem on our car was the gear selection switch that sits on the outside of the transmission. Massive job to change, and expensive due to the price charged by Audi for the switch, and where it is located on the left side behind the transmission mount. I hypothesised it was just some corrosion on the contacts inside the switch, so I just put the key in position 2 (engine not going), and moved the gear lever back and forth from P to Sport about 100 times to try and clean up the contacts. 2 years later it hasn't happened again.

I also had a similar problem on my BMW, which also has the ZF 5HP19 transmission (RWD version). In this case it was just the contacts on the plug that comes from the switch. I cleaned these up and the problem has never repeated itself.

If the codes tell you this is the problem, taking it to a dealership will just result in them telling you it needs replacing, with the associated huge bill (here in Australia it was going to cost about $1500). My experience tells me this isn't normally required.

I've pulled apart one of these transmissions, including the plug. The plug design makes them not prone to fail internally, so it's normally a electrical contact problem. If you want to have a look at the switch and what it does, have a look at the link below.

http://forum.e46fanatics.com/showthr...0#post14551400

As an aside, I don't think the Audi transmissions have the same reverse fail problems that other ZF 5HP19 transmissions have. The reverse drum that fails is a different design on the Audi transmissions, which is most likely a result of failures on other cars.