Überschwinger 150 hp (ARL)

What is the maximum allowable pressure drop across a safety relief valve (SRV)? I found some information online mentioning a value of 0.3 bar above the set pressure. So, in my case, that would be approximately 1.9 bar.

My analog LDA shows me (although only brief) peaks above 2 bar .

3 Phasen Biber wrote:

My analog LDA shows me (although only brief) peaks above 2 bar.

... so that the pressure is > 0.5 bar above the maximum setpoint? That's already well within the emergency operating range. The system isn't triggering an error (yet) because the emergency threshold (usually 0.3 bar above the setpoint) is being exceeded and then falling back below it early enough.

I think there's definitely something wrong here.

I almost thought that. Does anyone have any ideas for the next steps? I don't want to start messing with the pressure regulator right away, especially since I don't know which direction .

Could it be that the control valve is somewhat "slow" or "sluggish"?

It regulates normally, but these overshoots only occur when driving at full throttle.

3 Phasen Biber wrote:

I almost thought that. Does anyone have an idea for the next steps? I don't want to start messing with the pressure regulator right away, especially since I don't know which direction

1. Check the VTG (Variable Torque Generator) for ease of movement in the closed position area (injection test).

"In case of a questionable (or worse) result: For a few minutes, knead the VTG using the default settings of the MWB11 while the engine is running; this might help."

Quote:

Could it be that the control valve is somewhat "slow"

? ... or that a pneumatic hose is pinched/partially blocked. Both of these could be recognized by a hesitant extension of the rod from the VTG unit. Normally, it runs from stop to stop in an estimated 0.2 - 0.3 seconds.

Quote:

It behaves completely normally; these overshoots only occur when running at full throttle.

Did you check this using a MWB11 log, or do you consider anything below 1.5 bar to be an overshoot, even if the target is 0.8 bar and the actual value is 1.4 bar?

For me, only the pressure spikes exceeding 2 bar were of interest.

Sure, for me, it's a huge overshoot in the control loop when the actual value is 1.4 and the desired value is 0.8!

I need to do a measurement run and post the results on MWB 11.

Needle test? Create a vacuum and observe how long the VTG takes to move from stop to stop? Could you please describe that in more detail?

3 Phasen Biber wrote:

Injection test? . . . Could you please describe that in a bit more detail

No, because it's already explained in the technical article about the function and settings of VTG chargers.

I've made some minor adjustments to the can settings so far. => Still above 2 bar.

I hope you can make something out of my log .

3 Phasen Biber wrote:

I hope you can make something out of my log

.
Yes, the engine has been tuned (the target boost pressure has been increased from the standard value to somewhere above 1.6 bar – that's beyond the range of your software's target scale).

Therefore, the actual desired pressure cannot be determined, and consequently, the calculation "overshoot = actual value - setpoint" is meaningless.

The LD is increased by 0.13 bar.

So, what can I do now?

3 Phasen Biber wrote:

0.13 bar is the increased LD value. Also kann ich jetzt was tun?

1. Check the entire charging system for proper function. This will likely be unsuccessful, because the log diagram (where I entered the maximum LD target as [edit]2630[/edit] mb according to your specifications) doesn't provide any real indications of hardware errors.

2. Find a good source for skid-steer loaders and a workshop/garage space.

3. have the factory software reinstalled.

4. Look for a good tuner.

The holding pressure is already at 1.5 bar! => Then it should now be at 1.63 bar .

If you write 2.53 bar, do I need to subtract the atmospheres?

"However, based on my measurements, I'm seeing overshoots up to 3 bar! And if the analog LDA had a scale that went up to 3 bar, wouldn't we also see these overshoots?"

Wouldn't that have blown the engine a long time ago?

3 Phasen Biber wrote:

Wenn du 2,53 Bar schreibst muss ICH die Atmosphäre abziehen, oder?

Ja, Logdaten sind immer incl. Ambient pressure.
For colloquial pressure readings (and LDA values), always subtract 1 bar, or in high altitudes, use the lower ambient pressure.

The 2530 mb above was a typo and has now been corrected.

When running at full throttle, the gauge shows approximately 1.6 bar. So, the LDA displays the actual value (minus atmospheric pressure), which includes peaks exceeding 2 bar.

The LDA (likely referring to a pressure reading) shouldn't show values above 2 bar if everything is okay, right?

3 Phasen Biber wrote:

When running at full throttle, it displays approximately ~1.6 bar. So, the LDA shows the actual value (minus atmospheric pressure), which includes peaks of >2 bar.

Yes.

Quote:

Die LDA dürfte doch nicht über > 2 Bar Anzeigen, wenn alles i.O. ist, oder?!

Richtig, sondern kurzzeitig bis max. ca. 1,75 bar incl. Überschwinger, bei Deinem Tuning mit max. Soll = 1.63 bar.
Your "tuning" file produces significantly higher overshoot values (i.e., the peak difference between actual load pressure and target value, up to 0.35 bar according to the log) compared to the stock software, which has an overshoot of 0.15 - 0.2 bar, and that's a problem.
1. potentially material-damaging and...
2. completely unnecessary, as it can be avoided with more in-depth knowledge.

Regarding points 1 and 2, I understand both, but it works well even without any modifications.

My mechanic just said it shows too much information. Which is obviously nonsense. He probably doesn't have that much background knowledge, unfortunately!

Yes, it was a mistake, and I take responsibility for it.


What unfortunately doesn't help me with the problem right now => The tuning file needs to be removed again, which I also understand. But there must be another part that is defective.

This forum is my last hope.

3 Phasen Biber wrote:

Regarding points 1 and 2, I understand both, but it also works without any modifications/tuning. => Das tuning file muss wieder runter, ist mir auch klar. Aber da muss noch ein anderes Teil def. sein.

Please provide us with the logs, including the serial file and the MSG number – that is, the complete header of each log entry.
If someone has the original file on their computer, they can get a sense of what constitutes normal LD behavior.