Turbocharger Upgrade: GT1749 vs. VNT15 - Low Boost?

Hello everyone,

I'm having a small problem. The variable geometry turbine (VGT) shaft on my VNT15 turbocharger broke. Then, I bought a used turbocharger with the same part number: 038.253.019D. However, the label on the used turbocharger said "GT1749". I disassembled both turbochargers and couldn't find any differences.
After installation, the boost pressure is far too low below 3000 RPM, and the car is overheating.

I've read that these chargers somehow differ, and that boost pressure isn't always the same . I would like to understand why? And, more importantly, I need someone who can adjust the engine control unit software (I live in southern Germany)... preferably via private message.

I would be very grateful to you.
kane326

Hi Kane,

To begin with: GT1749 and VNT15 are compatible type designations. For example, in my TDI with engine code ASV, a VNT15 is installed, but it carries the Garrett designation GT1749V.

However, first, please explain in detail how the old VTG linkage fails. The mechanical linkage itself probably didn't break. Was it perhaps the membrane of the pressure sensor, or has the adjustment of the guide vanes become difficult?

What engine are we talking about here? What's the engine code (MKB)? What's the mileage? What's the year of manufacture?

Your problem description sounds very much like a misconnected vacuum control system or a malfunctioning turbocharger pressure regulation system.

Was betreffe die VTG-Stange des neuen (gebrauchten) Turboladers, wurde diese gedreht, oder befindet sie sich noch in ihrer ursprünglichen Position?


Best regards, Georg.

Hello,

It's best to always compare the Garrett part numbers or ensure that the turbocharger is designed for the same engine code.

If you don't always just buy used equipment, but maybe invest in a new charger once in a while, its durability and functionality should be guaranteed – as long as you don't ignore advice from people who have some knowledge about it.
I remember the statement "whether this will work well in the long run is questionable" regarding the installed charger.

If it were MY car, I would revert to the originally installed KP39B, specifically a new part. Or to a new GT1749VA. In both cases, the VTG adjustment would be the same as it was originally.

Best regards, Rainer.

Thank you in advance for your answers...
This is not a common car .

Okay, so the old turbocharger had "VNT15" directly on it, while the new one had "GT1749V". All I can say is that the VNT15 turbocharger came from a transversely mounted engine, and the GT turbocharger came from a longitudinally mounted engine.
Since I naturally used the search function, the results showed that the GT turbocharger is identical to its predecessor, the VNT15, on the exhaust side, and only differs in terms of boost pressure.

That's why today I connected the exhaust housing and the variable turbine geometry (VTG) adjustment from the GT turbocharger to my old VNT15 turbocharger ^^ --> and it fits. The car is running like it used to again.

I have to disagree with you, Rainer . The VNT turbocharger has exceeded the 2 bar boost pressure limit at least 50 times (due to the stiff adjustment), and it's still working today . I got lucky with the turbo! If I look at the problems my friend is having, who has now bought 4 turbos...
The VTG adjustment was difficult to operate due to deep grooves and wear marks on the blades. It's probably also my fault, since I disassembled and cleaned the loader once. In the process, I ground away the carbon deposits --> fail .

Yes, the KP39B would probably be the optimum... but then I would need another adjustment, and that costs money, and even worse, I don't know anyone who could put something suitable together for me .

By the way, I removed the turbocharger from the engine. It saved me 3 hours of time (for installation and removal).

Best regards,
Armin.

Command retracted...
"In the city or at low speeds (below 2400 RPM), I'm also missing 0.3 bar of boost pressure... This means: The turbochargers are not producing the same amount of boost on the exhaust side... failure."

Now I still need to find a VNT 15.

Quote:

VNT15

That doesn't say anything! It's just the designation of the underlying assembly.

Quote:

In the city or when driving at low speeds, below 2400 RPM, I'm now also missing 0.3 bar of boost pressure.

Not in large hallways?

I think you might be having a problem with the build-up of boost pressure.

What happens in 4th or 5th gear when the engine speed slowly increases under full load?

Similar behavior, you can see it here: https://community.dieselschrauber.org/en/viewtopic.php?t=25869

Probable cause: The vacuum sensor is not in its original position after installation.

The correct repair in this case would have been to replace the turbocharger with a new one.
But who would want that?

"I haven't changed anything on the turbocharger housing... The exhaust housing is slightly larger than the one that came with the VNT15 turbocharger, because I could only get the GT1749 turbo to spin without making grinding noises in the old exhaust housing... I probably lost some exhaust volume because of that."

Okay, it's already known that the VNT15 isn't particularly accurate... it would be too long to write the following nonsense every time .

Audi A3 8L, 1.9 TDI 85 kW (AUY engine), part number 038.253.019D.
Type plate identification:
VW/Audi VNT15, made in France.
GA3 038253019D
454232-2 CF C00023 F



What would be the exact designation of the KP39B loader?

Best regards,

Quote:

What would be the exact designation of the KP39B loader?

??

What prevents you from straightening and reusing original exhaust housings?

Unfortunately, one of the three screws on the VTG adjuster has broken off and is still stuck in the exhaust housing... Also, a bolt for the exhaust is loose, but it is still inside the housing.
Well, the turbo probably has over 200,000 km on it... I'll just buy a new one then. ^^

"Where was the KP39B turbocharger exactly installed? What engine code, year of manufacture, car model, and Garrett/KKK part number?"

If it originally came with a Garrett turbocharger, put one back in.

The KKK is not beautiful, let alone truly compatible with the software .

mullemaus wrote:

If an original Garrett turbocharger was installed, then install another one. The KKK is not beautiful, let alone truly compatible with the software

.
The original version contained something completely different.

What I don't understand is why new construction sites are constantly being set up using all sorts of cobbled-together used parts, instead of simply using a functioning new part, which is what the software is also designed for.



Best regards, Rainer.

lol... because I was in a tight spot. ^^
The plan was to get the pole working again... unfortunately, a screw broke... and since my friend had several loaders to choose from, I compared the GT and found it to be identical .

Now, I don't really have any other choice... I couldn't find a used VNT15, so -> New

Originally, there was something completely different in it.

I'm assuming, based on the initial post, that the name is Garrett?

Hello everyone,

I have a small problem. Specifically, the variable geometry turbine (VGT) shaft of my VNT15 turbocharger broke. Then, I bought a used turbocharger with the same part number: 038.253.019D. However, the type plate on it said 'GT1749'. I disassembled both turbochargers and couldn't find any difference...

Quote:

lol... because we were desperate ^^

Funny reasoning. If I need a charger, I order it, and it usually arrives within a maximum of 2 days.

You can see that putting together, sorry, some random junk doesn't lead to anything.
Let alone the risk of causing significant damage to the loader due to the accumulated debris, which could then damage sensitive components or even the engine.

I actually thought that you would have realized how much effort it is to then adapt the VTG adjustment to the respective "special component"?

Best regards, Rainer.

"Why do I have to justify myself now? I'm not stupid; there simply wasn't another way out. It was clear to me... the turbocharger looked identical. It had the same part number *shrug*."
1. I depend on the car.
2. I no longer live near the workshop.
On Monday, I had to be back at work .

Hindsight is always 20/20.