Dave,
Did you get this problem sorted out? I've got exactly the same problem with my 2005 A4 B7 S-Line Diesel but the difference is that mine is a 140 PS. I was thinking of getting a re-map to solve the problem but I don't really want to spend all that money if it is an easy thing to rectify.
Funny you should mention it but the problem is ongoing and the car went in last week for further diagnostics. It's been a while, but I've not had chance to take it back since the first visit.
I collected the car late so didn't speak to the technician but the the invoice (FOC) states "Attended to vehicle running issue. Carried out guided fault finding checks and found issue recorded with DPF pressure sender. Replaced faulty sender and all now ok. Will follow up with a report to Audi UK".
The problem definitely isn't resolved but I don't know where to go from here. I've had two 2.0TDI courtesy cars (140 A3 and 140 A4) and they both exhibit the exact same behaviour. There is an obvious hesitation in power between about 1800 and 2500rpm, especially noticable in first gear.
This never happened before the software update at the first service.
I'm due a second service in a month or so and will reopen the incident before it goes in. I'm tempted to try another dealer but I feel the problem is due to the software update. This must have been changed by the factory to rectify or prevent another issue. I've requested that software is rolled back to the original version, even just temporarilly so I can prove the problem. This can't be done apparently.
I would pay for a remap if it would iron out the problem but as far as I understand remaps won't affect running characteristics at low rpm.
If anyone has any other ideas I'd gladly accept them. If there are any other dealers with similar stories then please let me know. Apparently it's not a known issue and there have been no other reported incidents.
As it stands, I'd never touch another DPF Audi. I'm considering trading for a 3-series coupe, probably in about 6 months time. Either a 335i or the 335d twin turbo (although Evo mag has just taken an Alpina D3 onboard which I'll be watching with interest). BMW recently ran an offer on the M-sports pack so there should be some nice cars filtering through the used market shortly. I'll test drive an A5 quattro too, but despite its superior looks I really hope I prefer the beemer!
Regards, Dave