Passat 2,5 TDI BDH Leistungsverlust und Geräusch | Posts 16+

I am now trying to present and summarize everything as clearly and comprehensively as possible.


If the two chargers are identical (according to the nameplate), yes. If I remember correctly, there were different VTG control rings depending on the charger revision, but I no longer recall if that applied to the motor.

I forgot to upload the signs because I wasn't completely sure that they were identical. This has now been corrected.


Okay, here's the translation:

'Something else:'
The same problem with our two identical Passats.
Does the turbocharger pressure control system not work correctly in both Passats, meaning is the actual boost pressure too high? If so, then chip tuning is very likely the source of the problem, especially if the cars are identical.

No, in the other Passat, the boost pressure is rather too low (LOG now also uploaded – unfortunately a bit short due to the missing turbo button). Also, in Passat number 1, the boost pressure was slightly too low at lower RPMs *before* the intercooler was replaced (which it still is now), but above 2000 RPM, it was very good. It didn't exceed +/- 100 mBar.


Make sure to address all the points that have been mentioned and .

I'm not sure what else I can or should do anymore. I have also tried to systematically troubleshoot performance issues as much as possible.

MWB 7 - Temperatures are correct and consistent.
MWB 10 - Ambient and air pressure match when the engine is idling.
When the accelerator pedal is fully depressed, it registers as 100%, and both brake switch bits change state simultaneously.

The torque and soot limits are likely close together due to the tuning modifications.
The LMM (mass airflow sensor) and the N75 valve were replaced some time ago (without a valid reason).

The start of injection timing (MWB 4) from the top dead center (TDC) never differs by more than 1 degree.

Intake air temperature during maximum acceleration throughout the entire journey was 12°C; it wasn't colder outside than that.

The value of the AGR has been posted, and since it didn't elicit any reaction, I assume everything is okay so far?

The injection rate ratio of the fuel injector is between 50% and 62% at full load – are these values within acceptable limits?
I also determined the injection start timing in the base setting for idle using the MWB (presumably a diagnostic tool). It was found to be late at 4.6° ATDC (After Top Dead Center) and early at 14.6° BTDC (Before Top Dead Center). When set early, it misfired significantly.

Unfortunately, the exhaust pipe diameter has not yet been checked. Neither has the compression.

While browsing through the articles in this forum that discuss performance issues and their analysis, I came across a test to identify problems with the vacuum system. To perform the test, remove the vacuum hose from the canister and accelerate to at least 4000 RPM under full load. The lambda value (LD) should not significantly exceed the target value.
That's exactly what's happening now; the LD (likely referring to a specific system or component) is adjusting nicely and reaching its target value. It also has significantly more power compared to when using load control. With it, there are 147 horsepower, and without it, there are 181 horsepower.
Only the air mass is lower without control than with control, approximately 800 to 1000 mg/h.


If the boost pressure is significantly below the normal maximum value, even without any active turbocharger control, then the fault lies within the vacuum system (hoses / vacuum pump / solenoid valve / cables / engine control unit (ECU)).

I ordered the solenoid valve as a preventative measure last week and will replace it as soon as possible.
Of course, I also have a log from the trip without the VTG control system, which is attached.

I will do the same with the Passat 2. However, I assume that this one will not behave in the same way, since the LD (likely referring to a specific parameter or value) does not reach such high values in this case.

I hope I was able to contribute something in terms of meaningful data and insights! }

Thank you very much and best regards.

The chargers are different revisions that technically differ from each other, but should behave the same way.

If the file "LOG-01-003-008-011 blue without vacuum.csv" was created without the vacuum hose connected to the adjustment valve on the loader, then it is definitely incorrectly configured because even the target loading pressure is being reached. This brings us back to the "experience" I mentioned in my first post on this topic.

'Thank you!'

Therefore, the log is described in that way. Blue is the color of the Passat, so I don't get confused. The blue one has the new turbo, the second one is gray.
'There wasn't much power in the lower RPM range, but above 2600 RPM, there was a noticeable boost (as expected), and it ran better than with the hose attached to the vacuum sensor. It produced 147 horsepower instead of 181 horsepower according to kpower.'

Could you explain to me why the loader is misconfigured? If the guide vanes are set to their maximum open position without vacuum, and they also move to the open position with increasing speed even when there is vacuum, don't these two states contradict each other?

Best regards,

3BGV6 wrote:

If the guide vanes are at their maximum open position without vacuum, and if they also move to the open position with increasing speed even when vacuum is applied, do these two states not contradict each other?

No, a fully open or fully closed state is never reached in normal altitudes in any part/full load condition (otherwise, there would be no reserve capacity for high altitudes). This can be seen very clearly in the duty cycle of the N75 valve on a functioning engine.

"If the part is already pushing with 100% open VTG at 2600 RPM, then the settings are way off; normally, nothing should happen below 3500 RPM. I've driven enough vehicles with worn-out hoses."

Thank you all!

As you can see from the log, it already reaches 2.1 bar at 2700 RPM, and almost 2.4 bar absolute pressure at 3000 RPM.

And I thought that the N75 wasn't controlling it properly. But after 13 years, you might need to replace that part.

Now I will try to get a working charger, and the performance should then be back at 180 horsepower, but I fear that the noise will still be present. I will definitely let you know again.

Thank you and best regards.