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Discussion Starter #1
Hello,

I have an Audi a6 3.2l v6 with the tiptronic transmission.
The problem I am having is that the rpm jumps up and down at around 1000rpm. Just around where I think the converter seems to engage?
When in idle or over around 1500rpm it seems to be fine. It changes gear smoothly.
Could this be the torque converter? Could a simple oil change or complete flush fix this?
Milage: 140 000km
Transmission oil is never changes I think.
No faultcodes in VCDS

- Thanks!
 

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Without more info about your symptoms, hard to say.

the rpm jumps up and down at around 1000rpm.
Do you mean, abruptly? In a way that makes the car lurch forward or slow down more quickly than normal? Has it always done this or is this a change?

Just around where I think the converter seems to engage?
Engage? The torque converter is always "engaged," do you mean the torque converter clutch?

I don't know how much you know about cars, so excuse the recap if you know this...

The torque converter is a fluid coupling between the engine output (flywheel) and the transmission input shaft. It doesn't really "engage" or "disengage," it just lets the engine and transmission input shaft spin at different speeds, and multiplies torque when the engine is spinning faster than the transmission input shaft. Kind of like a "mushy, wasteful CVT.

The torque converter clutch (TCC) locks the engine output to the transmission input. In other words, it "bypasses" the torque converter so there's a solid connection. This gives better efficiency.

The TCC doesn't engage in low gears or at high load/acceleration. It doesn't engage in gears 1 or 2, not sure about 3, probably 4, definitely in top gear, when cruising at a steady speed. But if you step on the gas, it should disengage.

No faultcodes in VCDS
OK, so you have VCDS, good. You can log what gear you are in, and whether the TCC is engaged or disengaged while you drive. (I am not advocating watching the screen as you drive, just setting it up to log and reading it later.)

You would probably want to log these (at least)

Speed
RPM
Gear
TCC
Throttle position and/or load

As far as whether a fluid change will help, I can't say. That's a whole 'nother debate on changing fluid in a high-mileage unmaintained transmission. But, if your car has a sealed transmission (as I think all recent VW/Audi have) it's filled from the bottom while the car is raised level, so it's not a simple job for DIY.

Most dealers I have talked to recommend only topping up transmission fluid in non-maintained transmissions. If you don't know how full it is (as you wouldn't if it is sealed,) I would recommend taking it to a dealer and have them top up the fluid and tell you how much it took. (It will probably cost in the ballpark of $100 for them to do this.)

If the fluid was low, and the problem goes away after topping it up, there you go.
 
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