06 jetta-BRM turbo failing?

Would a failing turbo overboost like so?

I have a slight squealing after about 10-12 psi on my boost gauge

I don't notice any oil usage. Could a vacuum leak cause the overboosting? And what would cause the squealing noise?

Your screen shot is not showing much, not enough to qualify any diagnosis. Try posting single acceleration actual log, 3rd gear, flat ground, foot on the floor from 2000 to over 4000 RPM. The log can be graphed and it would tell more. A log of group 10 would help too, that would show MAF data next to actual boost to see how that sensor is responding. Scope screen shot doesn't look quite right, just can't tell a whole lot - you were in and out of the throttle too much.

Vac leak would tend to cause a big lag and underboosting, not what we are seeing so far from what you posted. Depending on how severe a leak it is possible under certain conditions for an overboost to happen, but not like what your pic shows. Were there any DTCs? If so, what?

If the turbo is howling you should be able to remove the convolute tube from the airbox, the plastic manifold on the turbo compressor it attaches to and inspect the compressor for shaft play and contact with the housing.

Possibilities? Maybe gummed up VNT in the turbo, dodgy N75 valve, super weak return spring in the VNT actuator, MAF sensor issue perhaps...

Edit: At first glance I confused requested and actual boost. Revised post to correct myself.

A5INKY said:

Your screen shot is not showing much, not enough to qualify any diagnosis. Try posting single acceleration actual log, 3rd gear, flat ground, foot on the floor from 2000 to over 4000 RPM. The log can be graphed and it would tell more. A log of group 10 would help too, that would show MAF data next to actual boost to see how that sensor is responding. Scope screen shot doesn't look quite right, just can't tell a whole lot - you were in and out of the throttle too much.

Vac leak would tend to cause a big lag and underboosting, not what we are seeing so far from what you posted. Depending on how severe a leak it is possible under certain conditions for an overboost to happen, but not like what your pic shows. Were there any DTCs? If so, what?

If the turbo is howling you should be able to remove the convolute tube from the airbox, the plastic manifold on the turbo compressor it attaches to and inspect the compressor for shaft play and contact with the housing.

Possibilities? Maybe gummed up VNT in the turbo, dodgy N75 valve, super weak return spring in the VNT actuator, MAF sensor issue perhaps...

Edit: At first glance I confused requested and actual boost. Revised post to correct myself.

Click to expand...

Alright. I'm just now starting to figure out the vcds so I'll do the 3rd gear accell and post the results with block 10 included. I'm probably going to pull the turbo this weekend and clean the vanes so I can rule that out. And while its out I could inspect for shaft play.

There's 3rd-4th full throttle. then towards the end just some driving in town.