Classic: Intake manifold pressure regulation deviation on Passat 98

Hello everyone,

After carefully studying the numerous contributions on this topic, I would like to obtain a "second opinion" on my problem.

Here are the facts:
The mentioned error occurs during rapid acceleration (according to MWB11, at approximately 2.5 bar). According to the vehicle owner, this problem has been occurring for over a year. Back then, maybe once a month or even less frequently, but now it happens on every trip.
The engine is a 1.9 TDI with 110 horsepower and a VTG turbocharger.

The following tests were performed:
- Check the airtightness of the pressure vessel using a vacuum pump.
- With the solenoid valve closed, the pressure in the hose leading to the pressure sensor is approximately -0.8 bar (vacuum).
- Solenoid valve replaced for testing purposes.
- Turbo removed and cleaned at the workshop.
- Check the boost pressure and vacuum in the turbocharger's pressure sensor using a pressure gauge while driving.
- SG swapped temporarily.
- Flexibility of the control linkage with vacuum pump, or... Actuator diagnostics of the control unit checked.

In a post, I came across the following test:
Disconnect and seal the hose from the pressure sensor of the turbocharger.
The charging pressure should not exceed 1.5 bar (absolute).
--> Interestingly, the boost pressure closely matched the target value or the driver's desired level. The peak pressure was approximately 2.2 bar (absolute). I'm also not getting any error codes. According to my understanding of how a turbocharger works, this shouldn't be possible with the guide vanes open, right?!?
My guess is that the pressure sensor isn't reaching the full zero position anymore. Could this happen over time?
Before I start tinkering with the rod, I'd like to hear your opinions!

I took measurements using a laptop. Once with the error present, and once with the turbo function disabled. Each, MWB 3.8.11.

Please find the Excel sheets attached.


Thank you in advance for any helpful information!

Klaus.

Does anyone have an opinion *desperate*?

Quote:

My assumption is therefore: the pressure cylinder is no longer reaching the full zero position? Could this happen over time? Before I start tinkering with the rod, I would like to hear your opinions!

It's probably like that, or someone messed with it.

Best regards, Rainer.