Turbo Vacuum Sensor Problems: Troubleshooting Guide

Hello.
I went to the trouble of installing a pressure gauge in the vacuum line leading to the turbo's vacuum sensor. Here's what I observed:
Gebe ich manuell Druck (Handpumpe)auf die Dose bleibt er nicht konstant sondern sinkt sofort wieder auf Null. Normal, or leaky?

Beim Beschleunigen geht der Druck mit ruckartigen schritten von -0,6 bis 0 bar hoch und fällt dann nach ein paar Sekunden auf -0,2bar Steuerdruck d.h. er beschleunigt nicht voll aus sondern quält sich ab 3300U/min. langsam richtung 4000. NSure.

Best regards,
Mike.
T3 TDI.

Hello Mike!

It would certainly have been more helpful if you had presented us with some data from a data logging session. Your statement about the measured control pressure is very vague.

It would also be helpful if you at least told us your motherboard model number!!!

Based on your measurements, it appears to be a VTG (Variable Turbine Geometry) turbocharger that is controlled by vacuum. It is perfectly normal for the VTG to be fully closed at low speeds to build up high pressure. As the engine speed increases, the mass flow of exhaust gases increases, and the engine control unit (ECU) must adjust the VTG of the turbocharger to a position that allows for lower pressure buildup, as you have demonstrated with your measurement. Therefore, what you described as the normal control process, measured by the control pressure, may indeed be the normal operating procedure.

More detailed information and measurements are needed for more accurate diagnoses.

Have you checked the standard errors for performance loss (e.g., mass airflow sensor, difficult-to-turn variable geometry turbocharger, ...)?
Use the search function!

Regards,
Alex.

Hello.
'Thank you very much for the reply. I was with a representative from Bosch and his mobile KTS diagnostic tester, and he said everything seems fine: vacuum pressure, temperature, mass airflow sensor, boost pressure, throttle position. He could only detect that the injection timing is slightly too early. What bothers him and me is that the car seems to 'fall into a hole' in 5th gear at 3300 RPM, meaning it loses a significant amount of power. Is this behavior normal?'

Best, Mike.

The engine (AHF) is not yet a common rail direct injection (Pumpe-Düse) engine, but it has the same basic structure and was primarily used in...
Bora uses...
Best, Mike.

Dieselmike wrote:

If I manually pump pressure (using a hand pump) into the container, it doesn't remain constant, but immediately drops back to zero. Is this normal, or is there a leak?

The (intact) can itself is airtight. Your observation suggests that the can is damaged.

Okay, Ulf.
That means it's broken, and there are no replacement parts available, only the complete turbocharger, which costs €610 plus tax. I'm going crazy.

Best regards, Mike.

Dieselmike wrote:

... they don't offer it as a spare part, only the complete turbo, which costs 610 euros + tax...

If I remember correctly, you should read the technical article about the difficult-to-operate VTG (a type of railway wagon). It probably even includes the part number...

HOW DO I GET ACCESS TO THE ARTICLE?

Best, Mike.

Dieselmike wrote:

HOW DO I GET ACCESS TO THE ARTICLE

Uff I actually hope that this question is a bad joke And then also in demanding capitalization Arrrggg

Hey everyone! There are a few rules in this forum, and two of them are particularly important.
1. Reading technical articles.
2. Use the search function.

You can find technical articles by looking further down on the main page, under the section labeled "Technical Articles," rather than going directly into categories like "Engine, Transmission, and Electrical Systems." The technical article "VTG Adjustment on VAG TDI Engines" is already available under the first section, "General."

Sorry, but these are really the questions that I regularly forget .

I have read the technical article and also spoken with the company that specializes in turbochargers, but unfortunately, 'all' of the data provided only applies to the Golf III.

My VNT turbo is either not repairable or not yet repairable, but it's 150 euros cheaper at this company.

I'm going to install a different turbocharger now (I don't have the exact model number handy at the moment) and I'll let you know more details later.

Regards,
Mike D.

Dieselmike wrote:

My VNT turbo is not repairable, or not yet repairable.

It's strange, as far as I know, the cans are usually just screwed on and should generally be replaceable - or is your can, for example, riveted?

Hello Ulf,

The can is somehow attached, but definitely not screwed on.

I'll put it aside for now until it can be repaired.

With deepest sorrow.

Mike.

'Note: At the end of December, amh-Booster GbR will offer chip tuning boxes for engines that are not equipped with a common rail injection system.'

Hello,
Okay, I also tried to get a replacement housing for my AFN turbo through various turbocharger rebuild companies. I also consulted the source mentioned in Ulf's article. The conclusion from all the companies I contacted was consistent: Garrett has not been supplying individual parts since the beginning of 2004. They only offer complete turbochargers for exchange. This is very frustrating for both customers, like myself, and the rebuild companies. Therefore, I can fully understand the difficulty in sourcing parts that is described here. So far, I haven't found a way to avoid paying around 120 EUR for a new housing, as buying a rebuilt turbo would cost 5 to 8 times that amount.
Bye.
Max.