Turbocharger Boost Pressure Check

Hi,

I measured the Leon over the weekend.
Specifically, considering Rainer's idea of building a VTG test tool, I wanted to ask if it's clearly visible in this log that the VTG is malfunctioning (as indicated by the feeling on the adjustment rod) and whether it might also not be operating within its full range of motion (which I can't assess because this is my first and only VTG).

Interesting aspects include:
A - The over-pressure values are higher the smaller the pressure increase. Almost 1.5 bar is a lot, even for an automatic shut-off valve, I would say.
B - This persistent, unwillingly high boost pressure, even when you've already taken your foot off the accelerator. The N75 valve might still be able to reduce boost to the 20% range, but it often stays stuck at 31%, and the pressure likely only drops because the engine speed decreases.
C - With longer periods of acceleration (for the first time at 4.), the boost pressure can actually decrease.

m;

Hi,

Quote:

Especially considering Rainer's idea to build a VTG test tool, I wanted to ask...

As long as nothing happens on the "other side" of the program with Ross-Tech, I'm at a standstill, and I won't invest any further effort in this.

Best regards, Rainer.

dieselmartin wrote:

Can you clearly see from this log that the VTG is sticking (which is what you feel on the adjustment rod)?

Hi Martin,

The oscillation of the LD (low-pressure diffuser) and the TV (turbine vane) even when reducing the surge is, in my opinion, quite impressive and suggests a stuck VTG (variable turbine geometry). However, it could also be caused by excessive clearance between the diffuser and the guide vanes (control hysteresis). Or a combination of both.

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and whether it might not also have its full range of motion anymore (which I can't judge, because it's my first and only VTG).

"In my opinion, the adjustment range is certainly sufficient, at least for the open-valve position: otherwise, the load demand (LD) would be above the target value in the maximum power (Pmax) range and could no longer be controlled."
To assess the closed-throttle behavior, it would be best to have a full-throttle log in 5th gear, from approximately 1100 to 2000 rpm.

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Of interest are: A - The overswingers, which are the higher, the smaller the swing. Almost 1.5 bar is also a lot for an ASV, I would say.

VTG, difficult to operate or worn out.

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B - this persistent, unwillingly decreasing boost pressure, even when you've already taken your foot off the gas. While the N75 valve might still be able to adjust to the 20s percentage range, it often stays at 31%, and the pressure likely only decreases because the engine speed is decreasing.

I'm somewhat familiar with this from the ALH. This is (also) due to the pre-tax vehicle tax.

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C - With longer accelerations (for the first time at 4.), the boost pressure can even decrease.

Well, the discrepancy between the actual and target values is still within an acceptable range. For a stuck VTG (velocity transducer), that's not unusual, in my opinion.


Here are two more tips for the chart:

1. For pure MWB 11 logs, the unused range from 0 to 900 can be omitted on the rpm and LD axes.

2. Calculated values for "Field 4" are more illustrative as a key press ratio because they represent a sharp actuation of the VTG (variable transmission gear) through high values.
Scale the right Y-axis to 0 - 80 .

Hi Ulf,

Should we leave it like this, or should the VTG be cleaned as soon as possible?

I'm looking for an estimate of how long it can still be driven/should be driven.

"Thank you."
m;

dieselmartin wrote:

Can we leave it like this, or should the VTG be cleaned as soon as possible? I'm interested in an estimate of how long you can still drive it/should drive it.

Well, LD-peaks up to 2.5 bar (or rather, the subsequent higher combustion pressure peaks) naturally put some strain on the spark plug screws each time.
If the sensor range ends at 2.5, the actual peaks could potentially be even higher -> LDA rules .

At 2.5 bar, the turbocharger should be able to handle that pressure relatively easily, even at only around 2000 engine RPM.
However, if you're still experiencing such high pressure spikes during load changes above approximately 3500 rpm, I would suggest trying to fix the turbocharger soon, before it becomes permanently damaged and fails.

Okay,

The VTG is now working. I once drove the tractor for a longer distance (KO-WIL) at almost its maximum speed, and after I had already removed quite a bit today, the VTG could be moved smoothly and without jolts.

Okay, let's put everything together and head to the slopes.
The situation with the "Überschwinger" hasn't improved.
Generally (yesterday I only checked it using a scope), he can regulate and maintain the desired boost pressure (even at 200 km/h). When you take your foot off the gas, the boost pressure increases (which seems to be due to the pre-turbocharger system).

So, now we need to rotate the rod longer?

dieselmartin wrote:

So, now we need to turn the rod longer???

Yes, I would give it a try.

Hi Ulf,

So that I don't have to break my fingers multiple times.

How many turns should I adjust the rod?

Greetings.
m;

dieselmartin wrote:

How many rotations should I change the rod by?

In your case, I would start with about 2 rotations.
If this immediately leads to a good result, you're lucky... but based on the changes you've achieved, you can get an idea of how much more is generally needed.
Then maybe it will be done with just two rotations.

Thank you.

Did I understand correctly that the rod needs to be detached from the adjustment lever so that I can rotate it two turns?

The threaded rod that came out of the pressure vessel felt very resistant to turning, and I don't want to force it and potentially damage the pressure vessel.

m;

dieselmartin wrote:

Did I understand correctly that the rod needs to be detached from the adjustment lever so that I can turn it two rotations? The threaded rod that came out of the pressure vessel felt very difficult to turn.

And I don't want to twist the pressure vessel.
Hmm, I'm not sure if you have a KKK or a Garrett turbocharger.
On my KP39, the threaded rod passes through a joint piece on the adjustment lever. To adjust it, you need to loosen the two nuts that hold the joint piece in the pliers, rotate them parallel to each other, and then tighten them again.

With Garrett, I only know the design with the threaded sleeve on the VTG lever, in which a knurled nut is located. The whole thing is fixed with a lock nut and painted with locking compound (unless someone has already shortened the shaft) }.
If you can prevent the knurled nut or the threaded stud from rotating while loosening the lock nut, no harmful torque will be applied to the can.

And yes, the threaded rod really doesn't rotate properly inside the container. It flexes a few degrees back and forth under load, but when it will "break" -> no idea...

I saw it like this yesterday:

Udose -> Threaded rod (I didn't see any hexagonal teeth for securing it).
On top of that, there's a mother and a pod, which then connect to the VTG.

My approach is therefore as follows:

Remove the retaining ring from the VTG -> Fear that it might pop off somewhere else.
Clip the VTG sleeves.
Tighten the nut (while holding the threaded rod against the base).
Remove two outer sleeves.
Lock nut.
Retaining ring installed (hoping it doesn't fly off again).

It looks exactly the same!
http://www.technologie-entwicklung.de/Gasturbines/VNT15-Turbo/vnt15-turbo.html

m;

dieselmartin wrote:

It looks exactly the same!

Ah, so it's Garrett.

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Udose -> Threaded rod (I haven't seen a 6-sided spline for securing it)

That's correct. But if you, for example, use a gripping pliers on the threaded end of the dosing side, you can still hold it in place .

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Therefore, my approach is: Remove the retaining ring from the VTG -> fear that it might fly off somewhere else

.
Happy sausage-making -> first, you have to get close enough.

I would secure the knurled nut or threaded sleeve with a (Grip) pliers, hold it firmly in place, and then loosen the lock nut. Any possible play in the sleeve on the adjustment lever also prevents any issues with the threaded rod inside the container.

Then loosen the knurled nut by two turns, tighten the lock nut, and you're done.
It always worked flawlessly with my AFN (except for the tight space to maneuver).

Yes, Garrett (sorry, I forgot to mention that).

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It has always worked flawlessly with my AFN (except for the tight space to maneuver in).

Did you approach this from a top-down or bottom-up perspective?

If viewed from above: I've been working on the assembly of the turbocharger intake manifold and EGR system since yesterday.

m;

dieselmartin wrote:

Did you approach the thing from above or from below?

From above.
For the G3 AFN model, the container is also located on top of the loader (with the VTG bar pointing downwards).

If the Leon has a "sagging can," I would probably approach it from below.
Possibly, I might encounter a case like that today (ALH in room G4).

Sure.

He has the hanging canister because the coolant reservoir is routed through the right wheel arch, as is apparently the case with all Golf 4 models.

Looking from above, it appeared that the axis body was quite prominent and obstructing the view.

Hmm, are you also working on something?

If the turbo didn't need so long to cool down, I would almost come those few kilometers to you .

m;


BTW:
The ASV (Anti-Suck-Back Valve) in the Ibiza has a fixed orientation because the compressor outlet points upwards (due to the low-pressure cooler being located under the transmission).