Passat 3BG AVF: No Power Until 2200 RPM

Hello everyone...

I'm slowly but surely reaching the limits of my knowledge and I'm hoping for some helpful input from you.

Regarding children who are at risk:
Passat 3bg 1.9TDI AVF 4-motion station wagon with 347,000 km.

The previously reliable car has virtually no turbo boost above approximately 2200 RPM.
The actual pressure is always below the target value (already about 100 mbar too low at idle). This continues until approximately 2200 RPM, and then the pressure increases significantly and matches the target value.

LMM...new.
Temperature/boost pressure sensor...new.
N75...new.
Vacuum system thoroughly investigated...no findings.
Measurement of the vacuum pump: -0.9 Bar.
Measurement at VTG pressure: -0.8 bar...Deviation in VCDS during LDR test: maximum 70 millibar.
"Vintage, smooth and jerk-free operation when controlled via VCDS, and adjusts via the end-stop screw."

Adjusting the set screw (which was previously marked, of course) resulted in no improvement, regardless of the direction it was turned.

It's also worth noting that the current power consumption at full load doesn't really change much... it's just very sluggish. Before, when using full power, it would immediately jump up. Now, it only increases when the boost pressure exceeds 2200.

Hopefully, someone still has a brilliant idea.
"Or, which values should I log for better analysis?"

Warmest regards... funky.

Ich gehe davon aus, dass du das VTG Ventilansteuerverhältnis bereits in VCDS geprüft hast und dass das MSG auch bereits vorher wirklich versucht die VTG scharf anzusteuern. K"Is this correct?"

Then we need to figure out whether the vacuum pressure to the VTG is incorrect, or whether the turbocharger is not regulating properly.
Can you test the vacuum in the VTG valve housing while driving? (For example, using a long hose through the window, or attaching a pressure gauge to the windshield wiper, etc.).

Yes, the correct ratio during the control process was 0.0% or 99.9%, and during that time, a pressure of -0.8 bar was consistently maintained on the cylinder.

Okay, I'll do the test drive right after work today and will send you a report immediately.

Edit:
Vacuum pressure at idle is -0.6 bar and slowly decreases as the engine speed increases.

Hello,

I would check the basic settings in measurement block 10 of the engine control unit to see if the VTG (variable turbine geometry) is moving sufficiently.
You can expect approximately 1 cm of movement at the adjustment lever. Avoid turning the limit stops or the adjustment rod, especially if you care about your loader and engine.

Please also check the vacuum system for leaks and don't forget the calibration containers.

Best regards, Rainer.

Hello Rainer, and thank you for your input...

Measurement block 10 will be checked tomorrow morning on the way to work.

The path of the VTG is perfectly designed from beginning to end. I also checked with a mirror to see if the engagement point is reached during the LDR test, and it is.

The vacuum system has been checked and is in working order, as noted.

I will report in tomorrow morning regarding measurement block 10.

Best regards,
Funki

Good morning, everyone...

As promised, here's the log from this morning.

If I somehow missed it while quickly reading through: Has the intercooler system been pressure-tested and is it 100% airtight?

The Jup is sealed after all the gaskets have been replaced.

A friend of mine is experiencing the same problem with an identical Passat. In his case, the VTG (Variable Turbine Geometry) is the cause. It seems to move freely, but it doesn't reach its full range of motion when necessary.

Therefore, it seems like it's leading to a new turbo being needed...

We will disassemble, clean, and rebuild it, as everything inside is likely clogged due to the mileage exceeding 300,000 km. Alternatively, we could source a used one beforehand and prepare it as much as possible, which would prevent it from sitting around for so long.

Update regarding the problem...

The turbo is now new (Garrett original).
The problem is still the same.
No power output until 2000-2200 RPM; then full power.

I don't really know what I should do anymore...

Does anyone have any more brilliant ideas?

You could check the oxygen sensor, but if it's faulty, you shouldn't be getting any power from the engine after 2000 RPM either.

Just disconnect the exhaust from the turbo and take it for a short test drive, making sure to insert something to keep the pipe from coming completely off the connection.

I once had a catalytic converter that was clogged, and mine sometimes had inconsistent performance. Depending on where the blockage was, it would sometimes have power and other times not.

Hello,

Why don't you check the measured value blocks from the engine control unit to see if the limitation is active due to a fault/air mass issue?

I'm sorry, but I cannot provide a translation without the text you would like me to translate. Please provide the text from the URL you mentioned, and I will be happy to translate it for you.

The problem you have has such a long beard... just use the available options!

Best regards, Rainer.