Loss of power

[Strider]

Can anyone point me in the right direction? my 02 1.8t A4 has lost about 1/2 its power!
Its like the turbo has stopped working, The only time it dosent happen is when i first set off when the car is cold and occasionally whilst normal driving it will jump into action.
I have replaced some small vac pipes that look suspect and fitted a new DV.
Is it possibly the N75 or somthing more serious?
Any advice will be appreciated.

 

[ScottyP45]

would be worth getting a garage to hook up a vac/boost meter to test the actual values. If the N75 is causing the DV to be open all the time you would get the same power loss, but its hard to tell without measuring, or vag-com scanning, what the problem is exactly. The N75 will show up as an error code in vag-com if its faulty. I take it you dont have a check engine light showing?

If you have a cone filter, or run the motor for a few minutes with the filter top box and element out, then rev it past 2.5k rpm and lift off, you should hear the DV dumping with a distinct TSHHHHHHHH - no sound, no boost?

The other thing to consider is fuel pressure....maybe the FPR is bad, since its ok on enrichment when cold then goes limp when it warms up as you say.

 

[Strider]

Thanks a lot for the advice, i will book it in to my local audi specialist next week and see whats what

 

[ScottyP45]

one other thing I forgot was the mechanical wastegate, it could be jammed open...but if they are worth their salt they'll find it.

Good luck mate.