Audi A4 - strange behaviour

I've had my 2003 Audi A4 1.9TDi for nearly a year and been very pleased with it however on 3 occasions I've noticed odd behaviour. After approx half an hour of enthusiastic driving on A roads (i.e lots slowing for
junctionas etc and then rapid acceleration) I seem to loose most of the power, acceleration is VERY sluggish. There are no warning lights or other symptoms. If I stop and re-start the car immediately the problem is gone. It's only happened on three occasions some months apart with plenty of similar driving in between
Any ideas as to the cause?
Mike
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auto or manual.
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tpow wrote:

Manual
Mike
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OK it was just that the auto's have a remember function (mine seems to) whereby they get used to driving techniques. I travel the same roads every day for 5 days per week, if I take a detour along a certain road that has a fairly steep hill, when I reach the top the box stays in 3rd or 4th for a while over the top. No matter what I try it will only change when it wants to.
yes yours is probably turbo related.
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Mike wrote:

It sounds like a sticking VNT mechanism on the turbo. It will probably leave a code 'overboost detected' or similar. The vanes stick, the turbo overboosts, so then the ECU shuts down the turbo. That's why turning it off clears it. This almost always happens after or during hard accelleration.
The official fix is a new turbo, though you may get an improvement by working the VNT mechanism back and forth a bit by hand.
http://forums.tdiclub.com/showthread.php?t 0910 may also help you out, and http://www.technologie-entwicklung.de/Gasturbinen/VNT15-Turbo/body_vnt15-turbo.html
shows the VNT mechanism in action.
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Chris Bartram wrote:

http://www.technologie-entwicklung.de/Gasturbinen/VNT15-Turbo/body_vnt15-turbo.html

Thought it might be turbo related, fortunately I have a warranty so I won't be getting my hands dirty!
Mike
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