Turbocharger Questions: Wastegate Turbo Explained

Hello everyone,

The "problem" is as follows:

The maximum boost pressure is only reached from approximately 2500 RPM. If I disconnect the pressure hose from the turbocharger, there is no air pressure in the hose when the engine is idling.

The impeller blades seem to be all there... at least, that's what my sense of touch tells me. I don't know yet if there are any scratches on the turbocharger housing, as I don't have a mirror. However, I can't feel any play in the turbocharger shaft with my fingers. And yet, I think the turbocharger is running too heavily, which could also explain why no air is flowing from the pressure hose of the turbocharger towards the "collection" suction pipe when idling. Perhaps it also explains why the boost pressure builds up too late, even for a wastegate turbocharger.

Unfortunately, I'm not familiar with this type of issue. The AU (vehicle inspection) definitely gave my car a hard time this week, but I'm not too concerned about it.

The AGR (Abgasrückführung) has been sealed for "long-term testing purposes" using a piece of metal. Otherwise, the car is in its original, production condition.
A measurement using VAG-COM showed a maximum boost pressure of 0.95 bar, which only occurred from an engine speed of approximately 2500 RPM.


Do you perhaps have any tips for me on what I could test to identify and fix potential errors?

Thank you very much for your efforts.

Best regards,
Wool.

Good morning.

Yesterday evening and this morning, I did some more research, and I found exactly what I had feared.

Possibly, the loading shaft is difficult to turn due to carbon buildup.

Is it possible to remove these deposits, if any exist, yourself, or would a replacement loader be necessary in such a case?
I couldn't find anything about that.

Thank you very much, and best regards.
Wool.
*who assumes it's not possible, but still has to ask.*

Roller bearings in a stationary position tend to be a bit stiff when they have plain bearings.
You should not attempt to clean a carbon-fouled bearing yourself, as balancing will be required after disassembly and reassembly. Attempts to clean it using Edding markers are done at your own risk.

The engine will carbon up, but only if you've been using too little oil and also turn off the engine immediately after a demanding drive.

wolle wrote:

Possibly, the loading shaft is difficult to turn due to carbon deposits.

Supplement to Christian's answer:
A slightly stiff, doughy feel is normal when rotating the shaft between two fingertips, as long as it doesn't feel stuck.
If you have to squeeze your fingers tightly together just to turn the knob, then something is wrong (e.g., carbon buildup).

Good morning.

First of all, thank you for your responses.
I created some more space in front of the loader so I can actually work on it properly, instead of just fiddling with it and bending my fingers.
After that, I was able to detect a slight cross-swell, but absolutely no longitudinal swell.
Unfortunately, I also had to really squeeze the fingers together quite a bit to turn the impeller. I need to compare this now with another turbocharger of the same type.
I would say, based on my gut feeling, that it's not going fast enough, but I'm not relying on that alone.

I can definitely say that this is still the original charger in the car, that I always have enough oil in the engine, and that I have never, under any circumstances, let the engine overheat.

I'm going to look into this... Because... My brother-in-law has a Kangoo... and it pulls away from me on the highway in the highest gear, between 80 and just over 120 km/h...
The same applies to a Polo SDI.
While I personally don't really care, it seems to me that something isn't right...


Best regards,
Wool.