Boost Pressure Regulation Difference

Hello, I've already read several posts in this forum about this topic, but I haven't found a solution. The situation is as follows:
G4 TDI-PD engine with 115 horsepower, upgraded by *** to approximately 140 horsepower.
Während der Fahrt mit einer Geschwindigkeit von mehr als 140 km/h ca. 5 Minuten, tritt plötzlich ein Leistungsverlust auf. Motor aus wieder an läuft er wieder normal bis zum nächsten Ausfall. Das Steuergerät spuckt folgenden Fehler aus 7958 P1550 008 Ladedruck Regeldifferenz. Es have been so far.
The following measures were taken:
1. All vacuum hoses checked and found to be in good condition.
2. Vintage item, function OK.
Replaced the magnetic valve for turbocharger pressure limiting.
4. AGR has changed.

I don't know what to do anymore...
Can someone help me?
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Hi.

... the installation of a boost pressure gauge.

Or a measurement run with data logging (measuring block showing actual boost pressure and duty cycle at the solenoid valve) until the error occurs.

Or even both - this could allow for the detection of measurement errors in the area of boost pressure at the same time .

Then you can see what happens next...

The car is going back to the dealer on Thursday, and then the mechanic wants to take me for a test drive. I think he'll be constantly reading the engine control unit (ECU) during that time.

"Hey Ulf, are you also from the Saarland? Where exactly are you from? Do you work at Audi or VW?"

Hi.

Quote:

@ ulf, you're also from the Saarland! Where exactly are you from? Do you work at Audi or VW?

I live near Kleinblittersdorf and I do car stories, but only as a hobby.

Okay, this morning I had a test drive with a VW technician.

Read measurement data block 10.
906 mg/H
999 mbar
2223 mbar
100.0%
931 mg/H
999 mbar
2346 mbar
100.0%

Reading measurement data block 11.
2710/min 2223 mbar 1621 mbar 92%
2370/min 2223 mbar 1224 mbar 92%

Here are the values that the diagnostic device is outputting. Can you make anything of them?

That is exactly the problem I'm experiencing (Bora 115 HP TDI AJM engine, no performance increase) .

My car has been at the workshop since Monday morning, and they've been trying to find the cause with three master mechanics. They've actually already replaced everything that could be replaced!

I'm picking up the car today because I need it over the weekend, but I was asked to return it on Monday morning.

I hope they find something!

When I used VAG-COM to go through the values according to the table (only idle speed, as it was difficult to press buttons under load ), I noticed something that was different from the target values:

Expected data:
Ad group 2.
Field 3: Operating Status
Advertisement: Target: 010.

It was 111 for me.

Can anyone explain what this is about? Maybe the solution is hidden here...

cesys wrote:

So, this morning I had a test drive with a VW technician. Read measurement data block 10. 906 mg/H 999 mbar 2223 mbar 100.0% 931 mg/H 999 mbar 2346 mbar 100.0% Reading measurement data block 11. 2710/min 2223 mbar 1621 mbar 92% 2370/min 2223 mbar 1224 mbar 92% These are the values that the diagnostic device outputs; can you make anything of them?

Since you haven't mentioned anything about the measurement conditions:
Both measurement blocks only provide a reading if the engine speed is between 2500 rpm and 3000 rpm and the accelerator pedal has been fully depressed for at least 3 seconds.
The readings must be taken at full throttle.

Regarding measurement block 10: the boost pressure seems too high to me.
Please inquire with *** about the target value for your chip.
Measurement block 11: It appears that the control unit is already in a fault mode. A duty cycle of 92% indicates that the boost pressure regulation system is attempting to reduce the pressure almost completely, which also explains the low values.

Was the engine control unit already in a fault mode when data block 11 was recorded?

Best regards, Rainer.

Hello Rainer,
The values were measured immediately after the performance degradation occurred.
The accelerator remained fully depressed (throughout the entire journey).

P.S. Sorry for the late reply, I was on vacation.

Hello,

Ask *** about the target boost pressure for the chip tuning.
In my opinion, the problem lies in a faulty VTG (Variable Transmission Gear) control system.
Check the VTG adjustment on the centrifugal fan to see if it's stuck.
Using a large syringe, apply suction to the vacuum sensor and check if all positions engage properly.
Total adjustment range: approximately 1 cm.

Best regards, Rainer.

I spoke with a technician from *** today who said that everything seems to be okay with the boost pressure (I emailed him the error code data), but the problem is likely mechanical.
The VGT (Variable Geometry Turbine) has been inspected by the VW workshop, and they say it's okay. However, it was checked in a cold state! The workshop is now asking the factory about a new turbocharger. I'm curious to see what they will say.
Best regards, Jens.

Hello,

What is the target value for the boost pressure?
Well, if the skid-steer doesn't cost you anything and it doesn't break down immediately like mine did, then it works out fine.

Best regards, Rainer.

Target boost pressure. Damn, I forgot to ask.
Turbo, if I have to pay, then it's "only 30%."

I can hardly imagine a defect with the charger; it usually works perfectly fine and without any problems.
Could it still be a leak somewhere where the boost pressure is escaping, or perhaps in the vacuum range? Are these areas actually sealable?

Best regards,
Jens

Hi.

... can be easily recognized by the visible oil traces (from the crankshaft end seal).
For hidden areas, it may be necessary to look around corners (using mirrors, etc.).

The suction range is usually quite short, which means that leaks should be detectable with a thorough visual inspection. The section between the mass airflow sensor (MAF) and the turbocharger is particularly important because malfunctions in this area are common.

I checked myself, and I couldn't see anything wrong – no damaged hoses, no oil leaks, or anything like that. Today, my mechanic called me and said the car needs to be shown to a representative from the manufacturer on September 3rd, who will then decide what happens next. I think the appointment is quite rude; I have to drive around in a car that's not (fully) functional.

Hello, to the specialists.
I finally got a new mass airflow sensor at the workshop yesterday. However, I haven't been able to test it on the highway yet and see if it resolves the power loss issue.
I subjectively feel that the car pulls better now, or responds more readily to acceleration. Could that be possible?

cesys wrote:

I finally got a new mass airflow sensor at the workshop yesterday. However, I haven't been able to get on the highway yet to test it and see if it resolves the power loss issue. I subjectively feel that the car now pulls better, or responds more to the accelerator. Could that be possible?

Hi.

It could be quite good because PD engines seem to react even more sensitively to the LMM (mass airflow sensor) readings than VE-TDIs.
Even a replacement below the defect threshold could bring about significant changes.