Wissensfrage zum Fehlereintrag bei klemmender VTG am AFN | Posts 16+

Hello Rainer,
I was of course looking at the pole while the laptop was working hard .
However, if you don't know the exact moment when the duty cycle switches from 0% to 100%, you won't be able to detect a brief 'stuck' state at the highest position.
That's why my idea is to use a vacuum gauge in parallel with the pressure sensor. That way, you can see everything that the sensor is currently receiving.

Best regards, Kassen.

Hi!

I've done it myself on my Golf 4, taking out the turbo and cleaning the variable geometry turbine (VTG). It's been working fine so far, and that was quite a few years ago. But it's definitely some tedious work.

A few years ago, a friend asked me to do something for him, but I didn't have the time or inclination, so I sent him to a workshop that I know. I knew that in cases like this, the workshop would usually just remove the exhaust pipe and then spray some kind of turbo cleaner or similar product directly into the turbo housing from a spray bottle. I don't know exactly what else they do.
However, that also worked, and the car has been running perfectly fine with it ever since.

Perhaps we can think about that and maybe try it out sometime.
Removing the turbo is quite a job.

Hi there,

Often, the problem isn't actually caused by soot, but rather by rust that spreads underneath the VTG (variable geometry turbocharger), which then causes the guide vanes to become stuck. However, the M3 screws are also often a contributing factor.

Good evening everyone,

This evening, I unscrewed the vacuum pump housing, just as Rainer suggested.
The VTG lever moves extremely easily throughout its entire range (1 cm)! No jerking or jamming is noticeable. You can hardly tell that this shovel mechanism is hidden behind it.
The only difficulty with this attempt is that you have to keep the threads of the two screws centered over the hole, otherwise they will rub against each other.
I will now install another pressure gauge to monitor the vacuum at the valve body (or proactively replace the pressure transducer N75 if it were not properly calibrated ).
At the latest, just before reaching the maximum boost pressure limit, both indicators must move in opposite directions (boost pressure increases, vacuum decreases).

Best regards, Kassen.

Hi there,

An N75 doesn't cost a fortune, but it can also be quite easily checked.

I would try blowing out the pressure line to the pressure sensor in the MSG (manifold), as it might be clogged with oil sludge. The boost pressure should be sufficient for this. Alternatively, you could remove the MSG and verschandeln the bore and the rubber hose inside.

Hi everyone,

Okay, after the test drive with an LDA (Linear Density Analyzer) and a vacuum gauge connected to the VTG (Variable Turbine Geometry) control unit, I know for sure:
The VTG mechanism is likely stuck at the upper limit with a high gas flow rate.

The boost pressure smoothly increases from 0.3 bar to 0.5 bar with the slightest touch of the accelerator, then returns to 0 bar when the maximum boost pressure is exceeded.
If the system is working correctly, the pressure gauge should display approximately 0.2 to 0.3 bar at maximum boost pressure.

I disassembled the ATL last night. I had to heat ALL the screws until they were red-hot before they would come loose!

Now, let's discuss the cause of the error:
Inside the open loader, I noticed that the adjustment ring is likely blocked by corrosion on the loader housing (see photo). Otherwise, I didn't find any other issues.
Can you simply sand away the rust here, or does that potentially remove a surface coating, which would then cause the corrosion to progress even faster?
I had already scraped away the area in the photo with a screwdriver. Before that, it was just small bumps.
The rest looks good and also operates smoothly thanks to the carbon film.

Best regards,
Kassen (the one with the dirty fingernails next week).

Hi,

you can grind it away.

Best regards, Rainer.

Hey everyone,

Yesterday evening, I sanded down the rust spots, of course after removing all the soot beforehand (I really need to go get a manicure ), and then reinstalled the ATL.

I just finished a test drive.
Everything is working great again! .
The acceleration feels noticeably smoother. Also, the automatic high beam assist (LDA) seems to be working much more effectively.
Onward to the next 170,000 kilometers...

Thank you to everyone who has supported me here. .

VTG technology is always capable of surprising us.
The small lever definitely moved easily before. I even checked it specifically before disassembling the device.
However, when I moved the adjustment ring while it was in the open but sooty condition, it clearly rubbed against the combination of rust and soot.
My guess, since all the flaps were moving freely:
The exhaust flow must have pushed the ring (via the fins) towards the rust spots, making it impossible to reset it, even with the strong spring force of the can.
Once the exhaust flow had decreased, the can could push all the components back into their resting position.

Best regards, Kassen.

Thank you for your feedback!

Hello everyone,
Hi Oldi!

Thank you very much for your feedback.

Regarding the registered error "Intake manifold pressure sensor, short circuit to positive," I would like to add for completeness that this can also be triggered by the engine management system (EMS) if the boost pressure suddenly and continuously exceeds the measurement range of the pressure sensor.
If the boost pressure is excessively high, the engine control unit (ECU) may no longer be able to distinguish whether the regulated limit has been exceeded or if the manifold absolute pressure sensor is defective or short-circuited to the positive terminal.

Even if it seems insignificant now, it might be valuable to future generations.

Best regards from Munich!