Robbirt

I have a 2005 A4 Avant Auto 2.0TDI which, for about the last month or so, when I accelerate to over 50mph the car seems to lose power. It actually feels like acceleration drains and the car is being held back however the revs still rise slowly. I just noticed a couple of days ago that when this problem occurs, the cruise control can not be operated. Once the problem occurs, the only way of clearing it is by switching off the engine and restarting the car and when this is done, the problem does not re-occur for the rest of the journey.

When the problem first started it only happened once in a while but it has now got to every journey. It's fine at slower speeds but once I accelerate to between 50-70mph, the problem kicks in.

Any advice would be genuinely appreciated.

nealbaldwick

This happened on my 2.5L tdi and the dealer replaced a valve in the air supply system to rectify the problem. It was not too expensive and carried a 3 yrs warranty.

gtmp

Robbirt - this is well described and matches the symptoms I'm getting. The fault is slowly getting worse, I have no confidence in overtaking due to missing power. I suspected Turbo related issue but the suggestion by nealbaldwick seems to make more sense, entire Turbo failure is pretty obvious I'd think.

Was nealbaldwick's answer correct? Did you find the problem?

Best, Gavin

the_duke

Last post on this was in 2012 so you'll most likely not get a reply. My best suggestions would be to post this in the forum matching your car and get someone to read the VCDS codes. Otherwise it's just speculation.