2.5 TDI BDG turbocharger overboost

Hello,

I once logged the boost pressure (in 3rd gear, full throttle) because my variable turbo geometry (VTG) seems to be a bit stiff. The boost pressure temporarily reaches almost 2.6 bar. Is that still okay?

The engine is a 2.5 TDI BDG with 140,000 km on the odometer.

Thank you very much.

What should I log?

[Translating...]

VCDS Lite...

The car reminds me a lot of my experience from 'back then'. Some 2.5V6 engines have something special. Even without pre-/main categories, he had shown no improvement. Manufacturing tolerances

Is the dataset up-to-date? Theoretically, you can check if the VTG (variable turbine geometry) is working by disconnecting the vacuum pump, but I don't know if it's easy to access that part of the engine.

Best regards, Rainer.

dieselschrauber wrote:

...honestly, I don't know if it's easy to get to that part of the engine.

It's doable with small fingers, but it's not going to be pretty.

How can I tell if the dataset is up-to-date?

I tried testing the VTG with a syringe. I couldn't detect any stiffness. The rod followed the movement of the syringe plunger directly. However, I'm not sure if I fully extended the 60mL syringe; it probably didn't reach the very end. The vacuum seems to be okay (-700 mBar). Could it also be the N75 valve? Unfortunately, the actuator diagnostics constantly switch abruptly between 100% and 0%, making it difficult to test properly.

I've found another peculiar entry in the log. It seems the boost pressure regulation was oscillating correctly here. This might have occurred during thrust mode. That's why I have no idea if it has anything meaningful to say.

Quote:

How can I tell if the dataset is up-to-date?

By posting the VCDS control unit information and having someone check if there's an update available.

Can it be recognized from here?

Address 01: Engine Labels: 059-907-401-AKE.LBL
Controller: 8E0 907 401 T
Component: 2.5l V6 TDI G000SG 0004
Coding: 02002
Shop #: WSC 63251
VCID: 361F603F0149
00006059 130 106KC318_1.V14834812390
No fault code found.
Readiness: Not applicable.

Yes, dataset for VAG part number: 8E0 907 401 T, software version 0004.

That's probably not the most up-to-date version. Is there any way to update it other than installing a new control unit?

Your engine control unit (ECU) can be updated normally via OBD by a qualified mechanic (or tuner who has a current, compatible data set).

Best regards, Rainer.

Sure? I always find information stating that the 2.5 TDI engine control unit (ECU) cannot be reflashed, and the technical product information (TPIs) consistently recommend replacing the ECU as the solution.

If you have access to the TPIs, why don't you simply look for the answer to your problem yourself?

It's flashable, and it's an EDC15VM+ unit.

Best regards, Rainer.

Regarding that specific problem, I haven't found anything. Only in cases of other problems (e.g., idling issues) with the BDG engine is the engine control unit (ECU) replaced due to a software update.

Okay, perhaps the control unit has a fundamental hardware problem that cannot be fixed by changing the software.
I honestly can't think of a specific reason related to the boost pressure control for that.

Why don't you just try replacing the N75 sensor? It's not that expensive, and it rarely causes any other problems.

Best regards, Rainer.