Turboproblem AHH, kaum Ladedruck | Posts 16+

Herbert wrote:

- Check VTG/loader settings according to the technical article. /viewtopic.php?t=10810

Specifically, take a look at the pressure build-up in the default MWB11 setting!
If nothing happens despite a 2 cm (approximately) travel of the VTG control lever, the guide vanes inside the turbine casing are most likely not moving.

Hello!

Okay, there's some news to report, but it's not good news.

The turbocharger was removed and sent to the workshop for inspection (where it was repaired).
der kam wieder, und wurde wieder eingebaut. He is okay.

Then, all the fuel lines were blown clean (the filter was already new), the fuel level sensors were removed and inspected, and everything was fine.

Unfortunately, what I wrote about the low vacuum in the turbo control system was a reading error due to a misread scale. I apologize; the vacuum is actually 600 mbar.

AGR has been shut down, no changes.

I watched the MWB 11, and during the drive, the boost pressure drops down to as low as 750 millibars.

We also conducted test drives, focusing on the Passat AHH, which has been problematic, and for comparison, with my wife's Golf ALH.

It has been noticed that...
"The fuel injection amount requested by the driver and the actual fuel injection amount are different."
IST is approximately 30% lower than the desired value.
The same thing happens with my wife's car.

Furthermore, the fuel temperature in my wife's car was approximately 25°, while in the Passat I was concerned about, it was around 45°.

Okay, let's start from the beginning again, so you don't have to re-read everything:

The problem is a lack of engine power.
No turbocharger boost, otherwise the engine runs like a well-oiled machine, but like an SDI.
Subsequently, the turbocharger was removed and sent to a repair shop.

Okay, so the Passat AHH used to have a cheap tuning chip installed, which has now been removed. There was some kind of box connected to the fuel injector wiring harness. It's been removed, and the wires have been re-soldered.

The Passat starts normally, the engine settings are correct, and I've checked and adjusted the ESP settings using a diagnostic tool.
That fits.

The exhaust was detached, the intercooler system was completely checked. The intake manifold is not clogged.

The turbo is spinning, but it's not pushing out much air.
Membrane dose working. Piston moving.
If you disconnect the vacuum hose from the turbo actuator while the engine is idling, the linkage will lower. When you reconnect the hose, the actuator will pull the linkage back up.
Although the journey seems a bit too long to me.

The error code in the diagnostic memory indicates a "turbocharger pressure regulation difference."


Yes, it's a mess, and we're quite helpless.

The speculations:

The workshop that did the turbo work.
I would ideally like to buy the entire car, and they suspect that the engine may not be receiving enough fuel, which is why it's producing too few exhaust gases. Unfortunately, it's located several hours away.

The neighboring workshop that accepted the job also believes that.

My opinion is that there might still be something wrong with the turbo, even though it was supposedly tested on a test bench.
I'm wondering, if the engine produces, say, 60 horsepower, shouldn't it also generate enough exhaust gases to properly drive the turbo?

Is there a way, maybe, just an idea I had...
From turbo to safety: Remove the exhaust pipe and intercooler hose, then start the engine and let it run with a little throttle.
Remove the membrane housing and manually operate the VTG (Variable Turbine Geometry).
Something like a foolproof turbo test?
Then to see that more than just a gentle breeze is coming out of the intercooler outlet?

Or is there a risk of damaging the turbo?

Hello Steffen,

Could it be possible that the VTG (Variable Turbine Geometry) is not actually functioning correctly (e.g., it's internally blocked, the adjustment ring is broken, etc.)?
You can safely disassemble the exhaust side of the turbocharger; if there's rust, you can gently tap it with a rubber hammer. Simply loosen the M6 screws on the exhaust housing.

Warning: The exhaust housing cannot be rotated relative to the central section because there is a small pin that fixes its position.
I'll take a picture later (it's a different turbocharger, but it works the same way).

Best regards, Rainer.

Steffen G wrote:

Hello! Okay, there's some news to report, but it's not good news. The turbocharger was removed and sent to the workshop for inspection (where it was repaired). der kam wieder, und wurde wieder eingebaut. He is okay. Then, all the fuel lines were blown clean (the filter was already new), the fuel level sensors were removed and inspected, and everything was fine. What I wrote earlier about the low vacuum in the turbo control system was unfortunately a reading error due to a misread scale. I apologize; the vacuum is actually 600 mbar. AGR has been shut down, no changes. I watched the MWB 11, and during the drive, the boost pressure drops down to as low as 750 millibars. We also conducted test drives with the Passat AHH, which has been causing us some trouble, and for comparison, with my wife's Golf ALH. It has been noticed that... "The fuel injection amount requested by the driver and the actual fuel injection amount are different." IST is approximately 30% lower than the desired value. The same thing happens with my wife's car. Furthermore, the fuel temperature in my wife's car was approximately 25°, while in the Passat I was concerned about, it was around 45°. Okay, let's start from the beginning again, so you don't have to re-read everything: The problem is a lack of engine power. No turbocharger boost, otherwise the engine runs like a well-oiled machine, but like an SDI. Subsequently, the turbocharger was removed and sent to a repair shop. Okay, so the Passat AHH used to have a cheap tuning chip installed, which has now been removed. There was some kind of box connected to the fuel injector wiring harness. It's been removed, and the wires have been re-soldered. The Passat starts normally, the engine settings are correct, and I've checked and adjusted the ESP settings using a diagnostic tool. That fits. The exhaust was detached, the intercooler system was completely checked. The intake manifold is not clogged. The turbo is spinning, but it's not pushing out much air. Membrane dose working. Piston moving. If you disconnect the vacuum hose from the turbo actuator while the engine is idling, the linkage will lower. When you reconnect the hose, the actuator will pull the linkage back up. Although the journey seems a bit too long to me. The error code in the diagnostic memory indicates a "turbocharger pressure regulation difference." Yes, it's a mess, and we're quite helpless. The speculations: The workshop that did the turbo work. I would ideally like to buy the entire car, and they suspect that the engine may not be receiving enough fuel, which is why it's producing too few exhaust gases. Unfortunately, it's located several hours away. The neighboring workshop that accepted the job also believes that. My opinion is that maybe something is still wrong with the turbo, even though it was supposedly tested on a test bench. I'm wondering, if the engine produces, say, 60 horsepower, shouldn't it also generate enough exhaust gases to properly drive the turbo? Is there a way, maybe, just an idea I had... From turbo to safety: Remove the exhaust pipe and intercooler hose, then start the engine with a slight throttle. Remove the membrane dosing unit and manually operate the VTG (volume totalizer). Something like a foolproof turbo test? Then to see that more than just a gentle breeze is coming out of the intercooler outlet? Or is there a risk of damaging the turbo?

Don't believe it's a fuel problem; that would manifest as large air bubbles, difficulty starting, and engine misfires.

Are boost pressure and altitude pressure difference the same when the engine is stationary?

What is the maximum air mass flow rate at full throttle, at 3000-4000 RPM?
Seal the AGR (Abgasrückführung) with a metal plate for testing.

Turbotest: Unscrewing the male connector - too much work: Here's an easier way:
Please leave the exhaust pipes and the LD hose connected. Connect the hose coming from the VTG membrane sensor directly to the vacuum source and then connect it.
Here's the translation:

"So, set the VTH to 'Full LD', monitor the LD value with VCDS, and apply the throttle SLOWLY. The LD target should start building pressure from 1200 RPM and continue to increase with rising engine speed and throttle input. Do NOT exceed 2000 mbar – immediately release the throttle! If the LD target is not reached, try running with the airbox open. The result?"

By the way: Is the ZR setting correct for KW-NW? Could something like that also cause a problem with a tooth misalignment ?

I have already uploaded the images to the corresponding article.
Okay, I'm ready. Please provide the German text you want me to translate.

Hello!

I finally found out the answer to the puzzle today:

There was a piece of cloth in the LLK.
It was likely overlooked during the repair of an accident damage.

The authorized workshop discovered this using an endoscope.

Great!
I learned something new again.

Steffen G wrote:

During operation, the boost pressure drops to up to 750 mbar.

If I had read that earlier, I would have predicted that you would have a blockage in front of the boost pressure sensor, or, for example, a collapsing hose in front of the compressor inlet.
The patch in front of the LK perfectly matches the symptoms.

Does one actually have it more often than one thinks ?