A4 power loss

[black a4]

I have had a persistant loss of power since buying my A4 TDI automatic, new MAF has gone in, had a service, including new oil,oil filter, air filter etc, my local in N Kent Audi independant says he has done a diagnostic, can't find a fault code showing

He says thats that there is a noise from the turbo sowing on idling for a while and says that revs go up a bit after idling for a while, I listened when I got home cldnt hear anything over the normal diesel clatter...


He says he needs to remove the turbo labour and check around £150
labour plus replacement turbo if shot,

any ideas guys please?:(

[black a4]

PS Car is a 1998 S reg 110bhp model

[paul b]

Was it a genuine MAF?

[black a4]

Yes it was, thanks for any help

[biker_bits]

Plastic engine cover off.
Is the turbo actuator rod free to move all the way IN and OUT? Mine was very sticky when I bought it. (Whereas my old Espace TD one required soaking for a few days to move at all!)
Check it with engine off - push it with fingers all the way in and it should return to all the way out freely. Is it attached to the turbo? It is not easy to visually check as the lug it attaches to is right under the turbo unit. Can be done by feeling it with your fingers though. Mine came detached on motorway as the clip retaining the pivot pin (and hence attaching the actuator rod to the turbo) fell off! New clip from breakers and a few hours trying to get the pin in and put the clip on - with the turbo still on the car, only air duct and the engine plastic cover removed.

Next, get somebody to rev the engine and check the the rod moves. Should see it do something from 1200rpm upwards. And hear the turbo 'whine'. Certainly should see it move quite a lot at 2000rpm (all the way up) - when the turbo should be at full boost.
If not, check there is vacuum at the turbo actuator hose- should increase as the engine is revved up. If the rod not moving, but the vacuum is there....
Engine off
Check the actuator diaphragm is intact by applying vacuum (suction by mouth if you don't ming the taste) to the vacuum unit of the turbo actuator - it takes a bit of effort, but this should make the actuator rod move.

Some useful hints : http://tdiclub.com/TDIFAQ/TDiFAQ-8.html#e

Don't rush to take it to Audi - do your checks first to save a good few £££ on a new turbo and labour! If you got new MAF and there is no fault codes on VAG-COM or other electronic diags - there's a good chance it is mechanical.