Boost Problem Audi A6 2.0 TDI BLB

Hi!

"I'm experiencing an issue with my Audi A6 4F 2.0 TDI PD, engine code BLB, where the turbo boost pressure is intermittently too high. The problem occurs approximately once every two weeks, and only when driving uphill. It then triggers the limp-home mode. If I turn off the engine and restart it, the performance returns to normal."

Address 01: Engine, Label file: RKS\03G-906-016-BLB.lbl
Control unit part number: 03G 906 016 BF. Hardware: 028 101 185 0.
Component and/or version: R4 2.0L EDC 0000SG 9553.
Encoding: 0000072
Operating number: WSC 29700 141 81827
"One error found:"

16618 - Charge pressure control: Limit exceeded.
P0234 - 000 - -
Environmental conditions:
Speed: 3171 RPM.
Torque: 134.0 Nm
Speed: 73.0 km/h
Last: 40.8%
Voltage: 13.68 V
Binary value: 11000000
Pressure: 1601.4 mbar.
Pressure: 2590.8 mbar.


Readiness: 0 0 0 0 0

I've already replaced the N75 valve, and the VTG adjustment is also working.

I once did a log analysis, and maybe someone here can spot an error.

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Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

Hello,

My parents' car has the same problem. The conditions are similar. It happens occasionally when accelerating fully. I'm currently preparing the log files.

Vehicle: Skoda Octavia 2.0 TDI

16618 - Charge pressure control: Limit exceeded.
P0234 - 000 - -
Environmental conditions:
Speed: 3045 RPM
Torque: 302.0 Nm
Speed: 104.0 km/h
Last: 67.5%
Voltage: 14.59 V
Binary value: 11000000
Pressure: 2152.2 mbar.
Pressure: 2519.4 mbar

After this, the engine goes into emergency mode until it is reset by turning the ignition off and on.

Hello,
The error message indicates a problem with the VTG mechanism.

My 2.0 BKD engine did the same thing. I fixed it by turning the ignition off and on. After that, I could put the engine under load without the turbo shutting off. However, the problem reappeared after a longer period of inactivity.

The VTG adjustment was checked using the injection method and showed no abnormalities.
Die Werkstatt sprühte die VTG Mechanik mit einem Keramikschmiermittel ein. That helped for now.
I suspect the problems are caused by the salt spread on the roads. (Winter issues)

Otherwise, the only solution is to replace the turbocharger.

Best regards,

Hello ChrisCross,

Even though it's probably too late: Your actual boost pressure is much higher than the target boost pressure. The turbo control system is unable to reduce the boost pressure.

I'm afraid your VTG diagnosis might be incorrect, or there might be a problem with your vacuum system. If you're still experiencing this issue, we can continue troubleshooting here.

Regards,
Guste.

@H.L.: Once we receive a log file, we might be able to provide further assistance.

Here is the log file: " color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

Please post in the upload section of this forum and link it here.

It's annoying when you want to help, but you have to click through several links and then, as a free user, you have to wait XX seconds.

Besides that, I would like to have a higher RPM range at full throttle (ideally between 1500-4000 RPM).

In your small diagram, I could only see that the boost pressure was significantly higher than its target value between 416 and 419 seconds. My assumption is that there's a problem with the VTG (variable turbine geometry) or its control system. However, a longer full-load log is needed for a more accurate assessment.

Regards,
Guste.

Okay, here's a log that was recorded after the error was cleared.

/viewtopic.php?p=165662#165662

Hmm, somehow the numbers don't seem to match the curves. Did you fit a curve function to the numerical values?

"During full load operation, between 90 and 95 seconds, the boost pressure oscillates slightly, dropping and then rising again between the gears. However, in the data between 90 and 95 seconds, only two data points are below 2000 mbar."

Without being able to consider the absolute numbers:
The LD (load disturbance) is being properly regulated under full load. While it drops off slightly with a bit of delay, I still consider this to be completely within acceptable limits.

In the log where the error occurs, the boost pressure is consistently too high. It looks like a problem with the VTG (Variable Turbine Geometry) control system, which seems to be working intermittently. Possible causes could include a faulty VTG actuator, but also the charge pressure control valve. Has the latter been replaced before?

Regards,
Guste.

Please also check the venting of the vacuum system. If no air can enter, the variable geometry turbine (VTG) will always be pulled to the 'closed' position.

Best regards, Rainer.

guste100 wrote:

Hmm, somehow the numbers don't seem to match the curves. Have you plotted a curve function over the numerical values? "During full load operation, between 90 and 95 seconds, the boost pressure oscillates slightly, dropping and then rising again between the gears. However, in the data between 90 and 95 seconds, only two data points are below 2000 mbar." Without being able to consider the absolute numbers: The LD (load disturbance) is being properly regulated under full load. While it drops off slightly with a bit of delay, I still consider this to be completely within acceptable limits. In the log where the error occurs, the boost pressure is consistently too high. It looks like a problem with the VTG (Variable Turbine Geometry) control system, which seems to be working intermittently. Possible causes could include a faulty VTG actuator, but also the charge pressure control valve. Has the latter been replaced before? Regards, Guste

.

"You're right, I chose a chart type that averages the curves somewhat. That's obviously not ideal, especially since the distance between data points is so large... I just did it quickly."
The error occurred immediately after the warm-up phase and the first full-throttle acceleration on the highway. After that, the error could not be reproduced. The car has less than 100,000 km on it, and no parts related to the turbocharger have been replaced yet.
Do you have any recommendations for lubricants that can be sprayed onto VTG rods?
Thank you very much for your help so far!

Quote:

Do you have any recommendations for lubricants that can be sprayed onto the VTG linkage?

For example, copper mounting paste. However, it probably won't make much difference, as the problem usually occurs internally.