Audi A3 8L 1.9TDI 130km: Turbo Vacuum Absence and Power Loss Issues

Hello. I have read a lot of similar topics and I have already learned a lot about this engine but I still have a problem with my tdi.

Hello.
Pajient Audi a3 8l 130km 1.9dti.

The car stopped pulling from the bottom some time ago (once from around 1800 it was already felt that it was pulling and sometimes from 2800-2900) the diagnosis made by the mechanic was a turbo. He took out and sent to a company that deals with regeneration. He came in and he was supposed to be around 2,000, but after a month he started to fail something, once he does not. Sometimes it pulls up to 3,000, sometimes from 3,000 and sometimes it falls into emergency mode and generally does not pull and then the maximum speed is 120km / h.
At the beginning I cleaned the egr - a noticeable difference on Plus but that was not a problem. Still not pulling. I cut off the flow to see if there would be any difference but it wasn't.
It turned out that there is no vacuum on the turbo. I took off the hose from the vacuum valve, sucked air in my mouth and inserted the screw in the hose - test drive and car regained power.
The first diagnosis is a vacuum valve, but when extinguishing the car, the throttle flap will not vibrate (and while sucking the throttle hose normally goes without any resistance), it is strange for me that both sensors should fail, unless the damper has not worked for a long time and now it has broken from the turbo.
But I had an interface from bmw and it is the same as from vag so I installed the vagcom program and there were two engine errors from the flow but by cutting it off on a trial basis and a second error from overloading the turbo and probably by driving on the screw in the hose.
Errors cleared short test drive and errors not recovered. (But to be sure tomorrow I will connect when I get back from work, maybe it would be a short trip to make a mistake come up again)
Amazingly, there were no errors on the n75 and egr vacuum valves I was betting on.
Further on, I come to the vacum pump. The high vacuum (checked with a finger) draws in strongly and the brakes work properly even when the brake is applied frequently.
And connecting the hose from the vacuum from the turbo to the Tee just behind the vacum pump (bypassing the vacuum valve) the car drives as it should, i.e. pulls from below 2 thousand.
So I bet for this pump is efficient but as I have read I like to loosen the metalwork from the pump and for me it is also loose when I move the hose. But despite this, the turbo turns on and the brakes work
Does anyone have any suggestions ideas what to check? I will add that the pressure hoses checked by the eye seem to be good. Also connected correctly to the valves checked with etk.

Since the vacuum to the turbine solenoid valve occurs, so do the solenoid valve from the extinguishing flap and these elements do not work, then you need to check whether these solenoid valves have a plus after the ignition switch and then the continuity of the wire between each solenoid valve and EDC - wires that give ground with EDC.
See if the pear changes position after starting the car. If it changes rather the valve is controlled.
There may be badly inserted hoses or damaged solenoid valves - you can actuate them briefly to check them.

So after driving 50km, error 17964 turbo undercharging appeared. (Install the original without any modifications and work around) (the first error 17965 was turbo-charged or short-circuited)
I checked the voltage on each solenoid and after turning the ignition on all 3 valves on Plus is 12v
And on the mass control: n75 constant value after ignition 8.8v on egr 11.7va on this small valve voltage jumps from 8-9v 8-11v 9-11v etc.
For each valve giving 12v for a short time you can hear the ticking as if the contactors / relays so suggests that it works.
I saw the vacuum hoses today and they are certainly well connected and tight.
I just didn't check if this pear moves after firing because not by e-mail as it did by itself. But I'll check it today.

I will add as a curiosity that while checking, e.g. n75 I connected the hose to the outlet (to the end that goes to the turbo) and blowing into it and sucking and at the same time giving voltage from +12 battery so that it is turned on and disconnected, the air was still flying, the valve did not cut off air supply.
But I don't know how this valve should work properly and what voltage to get.

I will write again that the car fires once and once it has to turn a few seconds, it has to turn 7-8 times.

Can the error about not topping up the turbo be caused by the n75 valve despite the fact that vagcom has no error about it?

Today, I also spent some time with audi, took apart and cleaned the vacuum valves, by the way I looked into the check valve and turned out to be broken, I replaced it with a new one full of hope that it still sneezes without power.
Observed with the car in the evenings as if it would drive faster (still not fully functional) more responsive to gas and how would the turbo be more often.

See if the pear pulls the turbine bar after firing the car. One person is enough for this. If it pulls it in, will it let go after unplugging the plug from N75.
Since you have a VAG, you can control the N75 so that it will open and close cyclically and you can watch if the bar moves. Block 11 in basic settings.
It is worth buying a large syringe and connecting it to the pear and see if this is the way the turbine barbell moves and whether the pear is sometimes leaky and therefore does not hold pressure. Having a vacuum gauge you can check the vacuum before and after the N75 and thus determine whether it works correctly.
In the error description there is information whether there is overload or undercharging - you have not written anything about this part of the error description.

What would I do if I were you?

- he looked carefully at the vacuum pear controlling the VNT operation - in these VAGA models the pears are the stem upwards, so with time the water flowing down the lever likes to get inside the pear causing its corrosion and problems with proper turbine control
- another aspect is the vacuum hoses and the vacuum accumulator

You have a diagnostic cable at your disposal, make group logs 003,008, 011, upload results to Excel and put it here, it will be easier to say something.

As for turbo pears, it is completely functional without holes and it runs smoothly.
The problem is that I don't have a vacuum gauge and I check the pressure at home.
I made logs 003 008 011 but static because I don't have a good laptop battery and it won't last longer than 2-3 minutes.

Today I also buried a bit and with the syringe I did a test (10cm3) I gave out just behind the tee for the vakum and sucked it in (but not immediately after about 10 seconds) later I gave the valve n75 and did not want to suck. But as I plugged the vacuum hose that goes to the air filter, the syringe sucked in easily and did a test drive (with the screw in the hose that goes to the air filter), the car goes normally, and when I remove the screw, the turbo does not work anymore. I will add that with this screw there is also a fire extinguishing flap in egr where without this screw it does not work like a turbo pear.


The error I had was:
17964 - Charge Pressure Control: Negative Deviation
P1556 - 35-10 - - - Intermittent

from the translation comes: 17964 P1556 462C
Turbocharger pressure (TC) - limit not reached> valve, poor intake flow, TC damage

If I have a screw in the vacuum hose that goes to the air filter, after firing the car, the pear barbell comes, but I don't have to wait a bit. And it doesn't move without this screw.

Vacuum connected according to this picture. In red I marked the place where I put the screw in and everything started to work.


And one more question I have, can I permanently disconnect the egr in this engine? From what I read, some do so because they say it is not needed

It was supposed to be log 11 in basic settings or basic settings.
If after clogging this hose the car drives and the hoses are fitted correctly, you have a damaged solenoid valve.
Replace it for the EGR solenoid test.
You attach the syringe directly to the pear and you do some strange tests. You unpin the hose going from N75 to the pear (unpin at N75) and here you give the syringe.

I replaced the n75 valve with an EGR valve but without any result.
You made the syringe stick in the pear hose and I did it too. Pear with a syringe alternated, pear functional as I wrote earlier. And since I already had this syringe, what was wrong to plug behind the valve (I did not have a vakuometer to check the pressure on the pump and behind the valve) so I used a syringe to check if the valve works at all and it turned out that it did not suck.
I put in the screw and rode for 3 days, yesterday evening I washed the engine and today the car started firing and went out. I took out the screw from the tongue because the n75 valve was buzzing and the car started to drive normally, I do not understand what's going on.
I exchanged a non-return valve in all this business because it was permeable both ways and cleaned the egr but it was 3 days ago and then I did not want to drive properly.
At the moment the car is fully functional, pulling from 1700-1800 rpm as it used to be.