Whine sound from turbo?

Dubsmb

Car: 06 Passat 2.0 TDI

I recently started hearing my turbo making a whining noise at low revs even when idle. I didn't want to keep going until the turbo would fail so I brought the car in to have them check it. At first they said the alternator is making the noise and then they called me later saying it is actually the turbo. I ended up getting a NEW turbo, not reconditioned and now the new one doesn't give out boost until about 2400-2500 rpm. If I floor it in second gear it slowly makes it's way up the revs and then suddenly a surge of boost. It's annoying trying to get out of intersections quickly as I can't get up to speed fast enough.

Also the noise I was talking about is still there but it's slightly quieter now. BTW it's a whining noise like a siren and it can only be heard low in the revs if I accelerate or press the clutch in to make it idle.

Any thoughts on what the noise could be? I read around saying it could be intercooler piping but just asking maybe someone has experienced something like this. I will also be bringing the car in again on Friday and I will update.

mookishboy

Lack of boost could be from the Actuator adjuster on the body of the turbo not being set right. The actuator is prevented from closing thereby leaving the by-pass open for much longer than normal.