BLS Turbocharger Surge: Causes & Solutions

98er_alh wrote:

Hello, "That's very illustrative. I would also expect the regeneration process to be short with a 0% load. Normally, it shouldn't even need to regenerate; the ~400 km were simply the distance traveled." I've set up a small construction site. My BLS has, since the beginning, developed a strong surge of power automatically when accelerating at partial load, especially in 2nd gear, around 1700 RPM. A diagnostic test revealed that the boost pressure is overshooting. Applying vacuum with a large syringe to the control valve easily opens it and maintains the vacuum for minutes. I've already thoroughly researched posts on similar topics. Someone else also mentioned that the switching valve of the EGR cooler might be involved. So, when I had the DPF removed, I checked the rod and it actually had a stiff point, which I was able to loosen somewhat by moving it back and forth. During actuator diagnostics, everything is functioning as it should. However, the jerking/lurching is still present. I then closed the corresponding vent outlet to completely exclude the switching valve. The jolt is still there. Can the adjustment mechanism only fail while the device is in operation? If so, what can I do to prevent that? best regards Andreas

This topic reminds me of an old idea I had, to install this "sphere."

Older (VTG) TDIs had a vacuum reservoir the size of a softball.
That would nicely dampen the pressure – that's my idea.

Here is a wanted photo of the sphere.

You should connect a pressure gauge and test it.

m;

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One should connect a pressure gauge and test it...

I actually did that. I connected a vacuum gauge to the windshield wipers and tried it out. Unfortunately, it didn't work. For me, the vacuum pressure seems perfectly normal both during operation and during the actuator diagnosis.

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Older (VTG)-TDIs had a vacuum reservoir about the size of a softball.

Okay, I actually need the opposite – faster ventilation when the control is released.
I've now been reading about mechanical wear in the process of further research. But how can I determine if it's present? Without disassembly, it's hard to get a good look, right?

Best regards,
Andreas

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Well, I actually need the opposite - a faster ventilation when the control is removed.

Above all, you need a smart log that allows you to properly assess the entire warm-up process.

So far, we can only see that he oversteers once. Unfortunately, the timing and the accelerator pedal position remain hidden.

The BV39 train on the BLS route seems to be operated without much care or attention.
(I just found the log from 2010, so he'll know what you're talking about.)

I believe a raw data file, meaning one that hasn't been processed, is more useful. In my opinion, the accelerator pedal position is absolutely essential... for example, if you just briefly lift your foot off the accelerator, all the values are already showing something.

It's certainly enough to illustrate the point.

I just remembered that non-original or defective mass airflow sensors can also cause these kinds of strange errors.

Sure.

"The word should be 'perspective'."

Just let it regulate for a few seconds, so don't necessarily run the log in the first gear .

The fact that I kept my foot on the metal should be evident from the constant pressure being applied. Lifting it would immediately cause the hook to drop.

Sure, a fresh log for this specific question should include information about the pedal.

m;

Okay.
Okay, I'm ready. If the log isn't correct or if anything else is needed, please let me know.

1. Acceleration
2. Second gear
3. Half-throttle - with a jerk, but then it reached 69% throttle.
Second acceleration, second gear, full throttle - with a jolt.
3rd gear, full throttle - with a jolt.
4th gear, full throttle - smooth acceleration.

Unfortunately, I was unable to complete turns number 2 and 4 due to encountering a cyclist and/or race officials.
Oh, I have a 6-speed transmission.

best regards
Andreas.

To be honest, the actual leveling process looks quite good to me, aside from that one overshoot.

Two things can be assumed:

- The VTG (vacuum-operated valve) is stuck when fully closed (vacuum sensor is fully activated).
- The turbocharger wastegate is stuck or not venting properly.

However, this doesn't really explain the so-called "jerk." Perhaps you could define exactly what's happening.

...and what do the other colleagues think about it?

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The VTG valve sticks when fully closed (vacuum sensor completely engaged)

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As far as I could determine through various tests: no - prompt response.

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The waste gate is stuck or not being properly ventilated.

During the test drive or in diagnostic mode, the pressure gauge showed an immediate response.

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Maybe you should clearly define what exactly is happening.

It's like suddenly having 250 Nm of torque instead of 200 (it feels like 300). It really pushes you into the seat. It's uncomfortable when you're in the process of upshifting. Either I keep the accelerator pedal below 1700 RPM, or I accelerate properly and reach the maximum RPM above 1900, and then it's okay.
"This has been the case since 50,000 km (approximately 31,000 miles), when I bought the car with about 190,000 km (approximately 118,000 miles) on the odometer. Before that, it had been driven mostly on the highway (95%)."
In the 4th, 5th, and 6th gears, you don't notice any jolting.

What I've noticed now is that the tip of the overswing is also visible in 4th gear. However, the acceleration was completely harmonious and powerful .

I still have an idea related to AGR today.
The actuator diagnosis of the AGR (Abgasrückführung) is functioning as expected, but the control of the switching valve for the AGR cooler shows no change in pressure. However, the valve moves approximately 90 degrees during the test.
"Furthermore, I noticed that when manually moving the valve, a hard point needs to be overcome after approximately 30 degrees of rotation. I then tested the valve using a syringe, and it functions correctly, and the valve is also vacuum-tight. Afterwards, I closed the hose and drove. Everything was as usual. I wouldn't have been surprised, as the part, according to the service manual (SSP), only opens when the water temperature exceeds 50°C. So, it's largely passive."
Then I went through the measurement blocks again and noticed the following:

Address 01: Engine Control Module (03G 906 021 FD)

13:25:04 Block 042: Exhaust gas recirculation, intake manifold flap.
-7.6% Learning Value (male) AGR Valve.
00000000 AGR-Steller Adaptation
4.7% Position (Actual) Intake Manifold Flap.
0.4% Position (Actual) AGR Valve.

Are the -7.5% figures normal?
Or does the valve simply think it's supposed to be closed? How should this be evaluated?
I had already removed the valve myself during the DPF cleaning: it was normally coated with soot, but there was no narrowing of the cross-section.

I'm not usually into novels like this, but once you get hooked, you know how it is.
Thank you in advance for your participation in solving the problem.

best regards
Andreas.

"Boost pressure fluctuations initially don't provide any noticeable acceleration."

It can only be achieved through diesel (logging fuel consumption and/or quantity) or mechanical means.

Does an engine mount fail, and if so, only in the lower gears, because that's when the force is sufficient to cause it?

I've already written something about the BLS motor mounts (at the end, it was almost impossible to start the engine without it making a loud noise).

m;

Hello Martin,

No, it's not a sudden, short-lived burst that stops. Instead, it starts properly from that point. Before that, he feels a bit sluggish.
Only with very little throttle does the additional boost (jerk) become noticeable and then subside, at which point it truly feels like an LD overboost.

best regards
Andreas.

Wild ideas:

- Logging flow rates.
- Possibly even log the jolts caused by the ABS/ESP system (there are nice acceleration sensors, I have no idea if they can capture the "butt meter" effect).

EDIT:
What year is your tractor?
Possibly, it was implemented in this way at some point, but it's no longer present in my system (MJ08, 11/2007), making it difficult for me to understand and reproduce.

m;

Possibly, in situations where the actual boost pressure is significantly lower than the target boost pressure, the engine control unit (ECU) is in a smoke reduction mode due to insufficient boost pressure/air mass. To investigate this, log measurement block 8, or simply ensure that nothing is obstructing the variable geometry turbocharger (VGT) adjustment.

Best regards, Rainer.

As an attachment, please find a log with the security identification number (ISIN) DE0008469104.
To be honest, I don't find anything unusual about it.
While logging, I noticed that the sudden surge occurs between 1500 and 2000 RPM, depending on the load, the initial engine speed of the test, and the gear selected.
It's just a matter of a small adjustment to get the loader unstuck. If the engine speed doesn't drop below 1400 RPM between attempts, the effect is reduced or disappears.
What if the intercooler has only a small leak? Similar to...?
Or if the AGR (Abgasrückführung) doesn't close completely (but this is indicated to the MSG - Motor Steuergerät)?
Is it really possible to simply close something for testing without any errors?

I want to reiterate that the car drives well overall. I think most average users wouldn't notice. I also don't even want to think about the comments that might be made during an imaginary visit to the workshop .
"But since I drove a BLS that was perfectly balanced in terms of throttle response, I've been particularly motivated to find the cause. Dieselmartin wrote in another thread, 'I just like it perfect.'"

best regards
Andreas.

Well, there it is!

EDIT: No, that's wrong, he doesn't even reach that point; he stays at the lower limit of the rev range.

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He remains just below the speed limit

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Please translate it for me .
Especially since the circled area is between 2500 and 3000 RPM?

ich sehe nun auch das die Überschneidung im 2. und 3., aber nicht im 4. Gang appearance.
And how did you reduce the speed curve?
Is this related to the datascope software - the latest version?

best regards
Andreas.