Performance Loss Above 130 km/h (AJM)

Hello,
I am newly registered, but I have also already read all the threads on this topic, unfortunately, none of it has helped me.

It all started with an engine failure: a broken valve, damage to the engine block, cylinder head, turbocharger component, and valves, with metal shavings in the turbocharger...

'After that, I ordered an AJM engine, including the turbocharger, from a car dismantler. The dismantler said it came from an Audi, but that the engines were the same, although, the engine's wiring harness was definitely different.'

The engine, including the turbo, has been replaced and it runs, but the power cuts out after 130 km/h.
Previous repair attempts:
- Solenoid valve replaced.
- LMM replaced.
- Pressure sensor replaced.
- Installed the charger box from the old turbo.

everything without success

'Yesterday, I installed a boost pressure gauge and did some test runs. The conclusion is that the power cuts out when the boost pressure drops below 2 bar; I suspect the electronics are going into a failsafe mode. The error code in the diagnostic memory says 'Boost pressure control difference'.'

Does anyone have any suggestions for what else I could do?

A friend of mine mentioned that it might be possible to adjust the travel of the VTG (Variable Transverse Gap) mechanism.

mgolz wrote:

The error code in the fault memory reads "Boost pressure regulation difference".

The error message "boost pressure regulation difference" usually indicates a stuck VTG (variable turbine geometry). How to fix a stuck VTG has been explained in many posts.

Using a diagnostic device, we were able to move the part .

It might be. A stuck VTG (Variable Turbine Geometry) simply means that the turbine blades are harder to move than usual. At increasing speeds, the blades open too slowly, and then the emergency mode is activated. In emergency mode, the blades open, and the engine delivers less power; the maximum speed is usually around 130-140 km/h. So, remove the deposits from the blades.

'The 'new' engine has only 8,000 kilometers on it, and it's already supposed to have deposits?'

To clean it, does the turbo need to be removed?

Should I drain the oil when I remove the turbo?
or doesn't much come out ?

Hello,

Before you start disassembling everything, I would recommend doing a measurement run.
Here in the forum, you'll find information on how to do it and which data is important.
The values might help to narrow down the source of the error.

PS: Have you ruled out all possible causes of the discrepancy in the rules (see knowledge base)?

all the possible errors that are listed here:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.
Can I rule it out?

I haven't found much information about that measurement trip.
How should I drive? I currently only have the LDA available.

mgolz wrote:

The "new" engine has only 8000 km on it, and is supposed to already have deposits

.

I also bought a vehicle with approximately 5,000 km on the odometer, about 1.25 years old, directly from VW in Wolfsburg. It seems they only drove it in the city and on the factory grounds. In any case, I also had a stuck VTG (Variable Turbine Geometry). The error code in the diagnostic memory was the same as yours.

Hello mgolz,

You can find everything about the measurement run under "Technical Articles" => "Tips & Tricks" => "Target Data".

@Michael II

That's fine, but I only have an LDA and no VAG tester available.
The test run with the workshop previously showed a boost pressure (at full load) of approximately 2500 mbar.
Unfortunately, I don't know any more than that.

and how does this now relate to the turbocharger replacement? should I drain the oil beforehand ?

Well, if you don't do everything yourself.

I found the bug; a small cause, a big effect.

My friend said that he checked all the hoses carefully.
and what do I find? a reversed connection of the hoses on the VTG pressure regulating valve!!!

Well, that guy, he's seen some things.

but still: if I want to remove the turbo, should I drain the oil ?

Hello mgolz,

'Hey, how fast was your car running with the hoses swapped?'

At 130 km/h, it went into emergency mode, but that's not surprising with a boost pressure of 2 bar.

Thank you to everyone:D

At 130 km/h, it went into emergency mode, but that's not surprising with 2 bar of boost pressure.

Thank you to everyone

Hi... so, with a boost pressure of 2 bar, you're doing pretty well. 2.5 bar would mean you have 1.5 bar of overpressure (which probably wouldn't be sustainable for the engine for very long). I also had that error message before, and I ended up replacing the boost pressure valve, and it went back to normal.

Best regards, Mike.