Turboproblem AHH, kaum Ladedruck | Posts 16+

Herbert wrote:

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

Specifically, examine 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).
It came back, and was reinstalled. 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've looked at the MWB 11. During the journey, the boost pressure drops down to as low as 750 mbar.

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

It has been noticed that...
"The driver-requested fuel injection amount 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°.

Well, 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 be chipped/cheaply tuned, and that modification has been removed. There's some kind of box connected to the fuel injector wiring harness. Removed, re-soldered the cable.

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, and the intercooler system was completely inspected. The intake manifold is not clogged.

The turbo is spinning, but it's not pushing out much air.
Membrane dosage is working. The drawbar is 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 much to me.

The error code in the 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.
He would prefer to buy the entire car and suspects 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 and let it run with a slight amount of throttle.
Remove the membrane dosing pump and manually operate the VTG (volume totalizer).
Something like a foolproof turbo test?
To then 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,

It's possible that the VTG (Variable Turbine Geometry) isn't actually being activated (e.g., it's stuck in the closed position, the adjustment ring is broken, etc.).
You can disassemble the exhaust side of the loader without any worries; if there's any rust, you can help loosen it with a rubber mallet. Simply loosen the M6 screws on the exhaust housing.

Warning: The exhaust housing cannot be rotated relative to the central section, as there is a small pin for positional fixing.
I'll take a picture later (it's a different turbocharger, but it's the same principle).

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). It came back, and was reinstalled. 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've looked at the MWB 11. During the journey, the boost pressure drops down to as low as 750 mbar. We also conducted test drives, focusing on the Passat AHH, which has been giving us some trouble, and for comparison, with my wife's Golf ALH. It has been noticed that... "The driver-requested fuel injection amount 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°. Well, 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 be chipped/cheaply tuned, and that modification has been removed. There's some kind of box connected to the fuel injector wiring harness. Removed, re-soldered the cable. 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, and the intercooler system was completely inspected. The intake manifold is not clogged. The turbo is spinning, but it's not pushing out much air. Membrane dosage is working. The drawbar is 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 much to me. The error code in the 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. He would prefer to buy the entire car and suspects 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 and let it run with a slight amount of throttle. Remove the membrane dosing pump and manually operate the VTG (volume totalizer). Something like a foolproof turbo test? To then 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 in fuel problems; they would manifest as large air bubbles, difficulty starting, and engine misfires.

Are boost pressure and atmospheric pressure difference at sea level the same when the engine is stationary?

What is the MAXIMUM amount of air that can be drawn in at full throttle, at 3000-4000 RPM?
Seal the AGR with a metal plate for testing.

Turbotest: Unscrewing the menbrandose is too much work. Here's an easier way:
Please leave the exhaust pipes and LD hose connected. Connect the hose coming from the VTG membrane sensor directly to the vacuum source and then connect it.
The VTH (Vehicle Test Helper) is set to "Full LD" with VCDS LD being monitored, and the instruction is to apply gas *slowly*. The LD (likely referring to a pressure or boost level) should start increasing from 1200 RPM and continue to rise with increasing engine speed and throttle input. Do not exceed 2000 mbar – immediately release the throttle if that limit is reached! If LD (likely referring to a specific performance target) is not achieved, what is the result of driving with an open air intake?

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

I have uploaded the images directly 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.
Probably, it was 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 happen more often than thought ?