Polo 6n2 1.4 TDI (2000) Undercharged Turbine: Error 17964, Replaced Sensor, N75 Valve & Vacuum

I have a small problem with the turbine in the 1.4 tdi from 2000. From the dynamic logs it looks like an undercharged turbine to around 2500.
Polo catches the note, after restarting it is ok. Vag crashes error 17964 - i.e. undercharging.
I replaced the boost pressure sensor, checked the vacuum to make sure I replaced them all.
I also checked the N75 valve and it works fine.
I also checked that the barbells do not cut and it also looks ok (pumping air with a syringe works throughout the entire range)
Logs from group 11 look like this http://vaglog.pl/log-011_x4osf9.html
Or maybe a clogged catalyst can show such symptoms?
When looking for the reasons, it turned out that the flexible connector is slightly leaky, I will replace it and I wonder if I should cut the catalyst immediately.


Maybe someone had similar problems or will be able to tell me something that can still be checked to find out the cause of the problem.

First of all, I would detach the lung from the blade bar on the turbine and check whether it can be moved in the entire range, without any cuts, and whether the blades do not cut. Second, a flexible joint, if it is leaky, the exhaust gases will run out, but it is behind the turbine and should not have much of an impact. I am puzzled by this undercharging at lower revs, only at the revolutions of 2079 is the first reaction of the N75 valve. Write how you made the logs.

I checked the barbells in such a way that I connected the syringe and pressed the plunger. The barbells walked in full range without cuts.
I made the logs in such a way that I spread out on three and somewhere from 1500 gas to the floor and to the end. The car was definitely warm because I chased it away on the bypass.

Write down how you checked the correct operation of the N75 valve. Did you check the 011 group with VAG in Basic Settings where the computer controls the N75 valve to periodically open and close the turbine geometry?

I wrote it wrong, there is no n75 but n21 as in the attached diagram. I took it out and checked that it closes and opens while energizing.

If you can, do the static logo 011 in BS and we will see how this valve is actuated.

like here in this video:
link

Only today I managed to make logs, see the link below
http://vaglog.pl/log-011_xqec3l.html
I would like to add that I always catch a note when it is cold in the morning, right after starting off. Later in the day it is already driving normally.

The logo shows that something is wrong. Whether the valve is actuated to 100% or 0%, the boost pressure does not change. This is how I look at this drawing and photos of turbines on the net and it turns out that you have no geometry in the turbine, only a wastegate valve controlled by an overpressure-controlled coo. If you have the option of connecting a pressure gauge to the hose that comes to the coo, check if there is excess pressure there by making the 11 BS static logo.

Unfortunately, I was unable to get a vacuum gauge, but I checked if there was negative pressure by connecting a syringe to the turbine bulb. I fired up the BS and group 11 again and it turned out that there was no vacuum. It is also not present before n21. What could be responsible for this

The pear is controlled by pressure from the collector, not by vacuum. Check that the valve is not letting the wastgate close.

I checked again and my pear is controlled by negative pressure, drawing air from the pear, the barbells move. In the first post I wrote wrong it should be pulling the air out.
In that case, what creates a vacuum for me that controls the pear. Unless I think wrong

Follow the thread to the ball. Check where the hose is led from. If you're lucky, you'll find a wipe. If not, replace the valve. Normally the vacuum gauge is connected in several places to find the cause.

I am still fighting the note, I replaced the n21 and unfortunately it did not help.
I replaced the boost pressure sensor, n21, all hoses and the error continues.
Could it be a pear that opens the valve not fully or too late, i.e. n21 gives pressure to the pear but it opens only at a higher pressure than it should

Have you checked the flow meter? What error throws?

Crashes error 17964 - low pressure regulation doladowania
I have not checked the fish pass, as it can affect it, I will check it.
The strange thing is that it always strangles it in the morning after firing the first time, then after turning it off and restarting it, it already runs normally.

Check the vacuum hoses going to the EGR solenoid valve and the EGR itself.