Emergency Mode: High Boost Pressure - Parts Replaced

Okay,
Here's a summary of my problem again. My GOLF IV TDI with 110 horsepower, manufactured in July 1998 and with approximately 160,000 km on the odometer, goes into limp mode whenever it reaches speeds above 130 km/h. A logging session (see attachment) shows that the boost pressure is always too high (error code 00575: intake manifold pressure control difference exceeded).
Regarding the car, it's important to note that this issue has existed since the purchase. The seller installed larger injectors (0.216 mm) in the car, but supposedly made no changes to the engine control unit (ECU). This whole situation is also being dealt with by a lawyer due to tampering with the odometer. He is trying to recover money. However, he advises against canceling the purchase contract due to the seller's financial situation. Therefore, I have to try to make the best of it.
The car had previously experienced turbocharger damage, requiring the replacement of the engine's lubricating system components and the turbocharger. In addition, the following items have already been inspected or replaced:

Boost pressure control valve (replaced for testing purposes).
The connector for the LD valve seems to be okay (if it's disconnected, then the turbo is off).
AGR valve (replaced for testing purposes).
Turbocharger replaced (due to damage, replaced with a rebuilt turbocharger).
Vacuum lines inspected and replaced.
VTG valve, easily adjustable when cold (tested with a syringe and VAGCOM).
A check valve was installed as an alternative to prevent backflow.
Boost pressure sensor (before the intercooler) has been replaced.


When starting up (from approximately 1200 RPM), a slight whistling sound can be heard. This noise occurs both when accelerating and when releasing the accelerator pedal (in which case it sounds like it's coming "backwards," similar to a turbine slowing down).


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Hopefully someone has a tip.

I'll check later to see if there's a hot axle, so I'll trigger the emergency brake, then head to a rest stop and also visit the VTG (a railway vehicle leasing company).
Otherwise, I'll check the MSG to see if there might be a broken seal.
Chip tuning is indicated.

First of all, thank you to everyone who has contributed so far.

Then read the owner's manual again carefully, and before you do any test drives with full throttle, fix the defective parts } first!

Simusas wrote:

How can you test a check valve? I just read that a check valve that is fully permeable can lead to problems with turbocharger boost pressure regulation? Yesterday, I blew and sucked on it, and it worked in both directions...

Is that supposed to be like that? }Then the thing is broken.
Could the engine possibly be chipped, or does it have a power box installed? Given the high proportion of (cheap/low-quality) junk on the market, problems with the emergency running mode are not uncommon.

See above. Post updated.

FA = Feature article... hovering over it will reveal more information. Try "FA".

See above. Post updated.

Have you ever tried adjusting the length of the VTG rods, either extending them or setting them back to their original length?
Turn it two more revolutions and then do another test run, but only using the MWB 11.

Best regards.
Sascha.

See above. Post updated.

I doubt your boost pressure sensor is faulty given the verschandeln curve you're showing (if you had logged diagnostic trouble code 8, we could be sure about it).

It looks like the engine control unit is trying to reduce the turbocharger boost pressure, but it's not succeeding.

If there were any blockages in the exhaust system, you wouldn't have a problem with excessive boost pressure. So, that's not your issue. It seems more likely to be a problem on the control side of the variable geometry turbocharger (VGT), specifically the vacuum system. Perform an actuator test while stationary. The turbocharger should then activate every 10 seconds for 10 seconds, and the VGT should move. If it doesn't, the vacuum system needs to be checked (are the hoses connected correctly, are they defective? is the solenoid valve working, or is it stuck at maximum boost?).

Have you already replaced the check valve?

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

See above. Post updated.

See above. Post updated.

Simusas wrote:

After having the engine cleaned, I experienced the same old problems again. ...

Water or water damage to the sensors?

See above. Post updated.

Simusas wrote:

I'm going to try driving the VTG in a second-by-second cycle. I read that to do this, you should activate the solenoid valve in the second-by-second mode using onboard voltage. How or where do I access the onboard voltage? Directly at the battery? What about the polarity?

Unplug the connector, connect two temporary wires from the battery to the valve, polarity doesn't matter.

See above. Post updated.

Simusas wrote:

I just took a look and found an additional cable between the fuel injector pump and the engine control unit (ECU) in the engine compartment.

I would say it's probably a tuning box or something similar, but besides a different connector, there's nothing else attached to it/inside it.
I've uploaded a photo. Could there still be something inside

Quote:

? If so, where??? The 10-ohm resistor, with its size, could theoretically fit into any connector housing. However, the photo looks more like a splitter, suggesting that the cables leading to the small connector continue towards a box. You can definitely assume that the engine has been run for an unknown number of miles and has been modified with an unknown chip and an unknown amount of fuel enrichment.

What about the motorcycle control unit? Would I be able to recognize a soldered-in chip there?

Quote:

If you are familiar enough with the normal appearance of an open MSG: yes. Chip tuning always leaves its traces in the diagnostic data (VAGCOM logs).

Is it possible to undo this? What costs will I incur if I replace the control unit??? } It depends on the tuner and where you obtain the new ECU from.