Help with error 575, I'm at a loss and have read through technical articles

Hello, after reading here for a while, I now need your help.
"On my 1996 1.9TDI A4 Avant (AFN), I have the error code 575 17-00, which indicates a 'Intake Manifold Pressure - Control Difference' issue."
I have attached a log file, but I'm not sure how to better organize it in Excel.
It has already been exchanged.
-LMM
- Air filter
- Charge pressure control valve (1H0906627A)
-div. Vacuum hoses from a friend of mine.
It's noticeable that, in my opinion, after replacing the turbocharger boost control valve today, the car pulls better and has improved acceleration/performance. Symptoms: Lack of power, maximum speed approximately 165-170 km/h. Current maximum speed approximately 180-190 km/h (not yet tested on the highway).
I've noticed that the difference between the target and actual boost pressure is high; I'm only getting a maximum of 1285-1295 mbar under full throttle.
Previously, the pressure didn't exceed 1025-1100 millibars, but unfortunately, I don't have a record of that.
He told me that the wastegate valve was defective, which I have now replaced.
Does anyone have any other ideas? I'm not sure how to best inspect the VTG rods, as they are located underneath the can.
Thank you for your help!
The log file is located at www.julian-koerpel.de/LOG28jun.xls.

Does anyone of you have any other ideas? I'm not sure how to best inspect the VTG rods, as they are located underneath the can.
Thank you for your help!!

The VTG rod can be seen relatively well; you might want to use a mirror to help. I think that your problem will be found exactly there.

For the testing or inspection process (e.g., using VAG-COM), simply browse the search results or read the relevant articles. If it's difficult to operate or feels jerky, the cause is almost certainly identified.

Okay, thanks for the tip. I tried it with a 60ml syringe. As far as I can tell, the VTG (variable geometry turbine) seems to be moving properly, however: When I maintain the pressure (i.e., keep the syringe pulled), the VTG initially moves "up" = closed. But after about 2-3 seconds, it moves back down = open, even though the pressure remains. I initially thought it might be due to the syringe, since I connected it directly to the vacuum chamber (potential leak, etc.), but it doesn't seem to be the case. I know, it's a very vague description, but do you have any ideas?
The error message is still 575 17-00 (sometimes also 17-10). Is there anyone here who is reading this and is from the Rhine-Main area?

Thank you for your help!

Hi.

Quote:

After approximately 2-3 seconds, however, it moves back down = open

Then there must be a hole somewhere, for example, in the hose leading to the pressure vessel or in the membrane inside the vessel. If I were you, I would replace all the hoses, as damage from rodents may not always be immediately visible.

Best regards, Rainer.

Okay, I'll check it out. Although, the hose connecting to the turbo is brand new. Could the turbo itself be faulty? Has anyone here checked the turbo's values? Thank you all!

The turbo pressure is much too low. I suspect a leak in the hose, broken plastic T-pieces in the hose, or a faulty vacuum pump (which would affect the brakes).

In short, either there is insufficient vacuum reaching the diverter valve on the loader, or the diverter valve itself, or the loader, is defective.

-> Ulf wrote something about that once, mentioning things like injection tests, etc.

Best regards, Rainer.

Okay, the brake is working normally. I'll do a more detailed spray test tomorrow. Is there a way to see the pressure that's being applied during driving (i.e., the vacuum at the canister)? Could I use a T-piece and connect it to the car with a gauge? Or is there an easier way to do this? How much pressure should it be at? I seem to recall something about 600 millibars.
P.S. Since I've had the car (2 years), there's been a whistling sound coming from the front when I accelerate. I think it might be the turbo, but it only happens at the beginning when the engine is cold, or during the first few kilometers. It only occurs at a specific pedal position, but I can't describe it more precisely. It changes when I press the accelerator, and then it disappears completely.

Greetings.
Julian.

Ah yes, whistles: A large hole in the intercooler piping = loss of boost pressure. It's almost too obvious; you probably already figured that out yourself.

Best regards, Rainer.

Jo Rainer So, definitely no big hole. I think that's the "typical" turbo whistle. Can you perform actuator diagnostics with the VAG entry-level version (I bought the kit from here), or is that only possible with the full version?

Hi,

The actuator test is likely to be less functional (a license may be required). Just try it out; I don't have anything else I can do right now .

Best regards, Rainer.

Okay, I'll try translating it now. What I've noticed in group 3 is: I almost always have a higher MAF (actual) value than MAF (specified). Is that normal? You can see the data at www.julian-koerpel.de/MAF.xls. And at www.julian-koerpel.de/Group10.xls, there are also, in my opinion, too low values (Mass Air Flow + Manifold), at least when I compare the values to the specified data from http://www.dieselschrauber.de/Solldaten_4_Zylinder_VE.html.
Sure, here's the translation:

"Do you have any ideas?"

LG
a desperate A4 driver.

Quote:

I almost always have a higher MAF (actual) value than MAF (specified). Is that normal?

Yes, that's good.

The cause of the error is most likely as I described. In neutral, the adjustment lever of the VTG (Wabeco coupling) must be pulled all the way to the stop.

Best regards, Rainer.

Okay Rainer, did you also look at the data from Group10? I'm going down now to check the T-pieces, etc. Before my friend replaced the vacuum hoses, the car would intermittently go into limp mode at speeds of 70-110 km/h, and it was noticeably jerky. Since then, however, I haven't felt any hesitation, and the acceleration from low speeds is reasonably good, but I'm not reaching the maximum speed, and when going uphill, it feels like I have a full trailer attached . The boost pressure is there, but it's just too low.
Thank you for your help; I'll get back to you again this afternoon .

Something about this log seems very strange to me.
In the MWB 11, it is clearly visible that the target LD (light intensity) is not being reached, but why is the TV (transmission voltage) then above 90%? I think something is incorrectly connected (possibly the LD sensor is defective). Furthermore, with such poor values, the emergency mode should activate after a few seconds. Is the car chip-tuned?
You should double-check the catalytic converter (for leaks or cracks) and see if the exhaust manifold has any cracks or if it's not properly attached to the cylinder head.

Hello everyone
I'm incredibly frustrated with Audi and similar companies... After having absolutely no knowledge of turbos, engines, etc. beforehand (I'm a businessperson ^^), and having read up on the subject, I discovered the problem myself - a small mistake on their part. Audi assured me that the vacuum system was okay... However, since the VTG rod wasn't moving when the engine was idling, I disconnected the hose from the sensor. There was no vacuum. Then I checked the solenoid valve, the connections were correct, but again, there was no vacuum pressure. Further up at the AGR valve, there was also no vacuum. And then, on the first hose leading to the AGR (which then continues down via a Y-connector to the solenoid valve for boost pressure), I heard a whistling sound when I blocked it with my thumb. I turned the hose, and what do you know: a hole due to abrasion. Two hoses had rubbed against each other, and the one coming from the vacuum pump had a piece of shrink tubing on it, but it wasn't sealed. And: All values are OK, it's pulling better than before, that's my impression. It seems like an "X" piece had been missing for a while to keep the hoses apart. Small cause = big effect. Unfortunately, I relied on others who charged me money for a "diagnosis," a new mass airflow sensor (MAF), and a new solenoid valve (about 300€ total). Well, now I'm stuck with a MAF sensor that's working fine and a solenoid valve where I broke off 2 connectors while taking it apart... But: He's running again and it's fun!
Thank you all for your help. I recommend this forum to every diesel car owner!

LG
Julian.

Okay, Thank you for the feedback!