Ladedruckaufbau AFN träge, Istwert zu niedrig | Posts 16+

2. The LD drops to 0.5 bar, but the MSG remains in the 'Dremo' state?
Bei ~ halbem (!) LD müsste das MSG doch dicke in der Rauchbegrenzung kleben ?

@Roger
Yes, absolutely correct, except that the LLM (likely referring to a diagnostic tool) is, for some reason, giving maximum values for the air mass. However, this can usually be seen clearly even without a VAG-Com diagnostic tool.
Something is fundamentally wrong here.

3. What is the duty cycle of the LD control valve?
Recently, there was a lengthy discussion about that, and I don't want to get involved in it, especially since I don't have any personal experience in that area.
@Jochen:

I now know it for the ASV/AHF VTG exactly :

Small PWM values mean VTG is closed -> high LD.
Large PWM values mean VTG is open, resulting in a smaller LD.

Therefore, the control system is fundamentally compatible with the LD architecture.

@Jochen:
Er hat ja eine separate LDA, die wohl das gleiche anzeigt.

Oh überlesen..
Best regards, Jochen.

Roger wrote:

1. What is the LLT (Lowest Limit of Tolerance) value? Is it 20-20 degrees? "Can it go any higher? That seems unlikely. I can easily achieve over 50 degrees Celsius even with the current weather conditions. Or were you referring to a DELTA of 20-25 degrees?"

Hello Roger,

Okay, the measured values are making sense to me. Since the boost pressure only reaches 0.9 bar for a few seconds, but mostly fluctuates between 0.3 and 0.6 bar, the air doesn't get that warm. The slight warming that occurs during the compression of the air to only 0.5 bar is easily offset by the coolant. Therefore, there will only be a very small temperature difference compared to the ambient air. That difference was around 10 to 12°C.
I don't want to argue about whether the actual temperature is being measured here. However, since the values are so low, the engine control unit (ECU) shouldn't be reducing the boost pressure, regardless of whether it's accurate or not.

Quote:

2. The LD (Low-pressure alarm) drops to 0.5 bar, but the MSG (Main Steam Generator) remains in the "three-motion" state? At roughly half the LD (load distance), shouldn't the MSG (message) be clearly visible within the smoke boundary?

"I don't see a reflection of the boost pressure in the fuel injection amount. It's injecting fuel as if there were full boost pressure. The target boost pressure is actually calculated based on the fuel injection amount, so the causality is reversed."

Quote:

Er hat ja eine separate LDA, die wohl das gleiche anzeigt.

That's correct. The LDA display corresponds to the measurements from the VAG tool, as far as we can visually verify at this point.

I'm still amazed that the desired boost pressure is set to the maximum, but the control unit is reducing the duty cycle, which in turn causes the actual boost pressure to decrease.
Even if certain parameters were to cause the engine control unit (ECU) to reduce the boost pressure, why does the target value remain constant? And the boost pressure always faithfully follows the duty cycle, so the turbocharger does exactly what the ECU wants.

Regards,
Jens.

Jochen_145 wrote:

ausser der LLM gibt hier, warum auch immer, Maxwerte für die Luftmasse.

Hello Jochen,
"The LMM (Mass Air Flow sensor) is now reporting maximum values (1275) because I replaced the LMM with a diode. However, this doesn't directly affect the boost pressure, as long as the EGR (Exhaust Gas Recirculation) system isn't interfering, which is not the case for me since I don't have one."

I'm going to do some more measurements tonight using various measurement blocks.

Regards,
Jens.

I'm going to threaten the STG tonight.

If it doesn't become reasonable, I will convert it to a fully mechanical system (ESP from AGK) and a wastegate turbo. Then, it will be melted down .
Maybe this will help.

to LLT:
I agree with Roger; a delta of 10-12 K and an absolute LLT (Lowest Limit Temperature) of 20-25°C seem very low, even with a maximum LD (Low-Density) pressure of 0.5 bar.
Furthermore, I suspect that the liquid cooling system (LLK) in that bus (?) cannot be optimally cooled. A temperature difference of 20-30 K seems very optimal in the summer, which means it can only be achieved with properly cooled LLK and sufficient speed.
But as you already wrote: the LLT (Low Load Torque) doesn't seem to be the reason why the engine is reducing power.
I am unable to translate "haithamina" because it does not appear to be a word or phrase in the German language. It may be a misspelling, a proper noun, or a term from a specialized field. If you can provide more context or clarify the intended meaning, I would be happy to assist you with the translation.

Das hat aber keinen unmittelbaren Einfluß auf den Ladedruck, solange keine AGR dazwischenfunkt, was bei mir nicht der Fall sein kann, da nicht vorhanden.

Hello Jens,

'That's right, but that's the reason why your motor isn't reaching the torque limit, where it should be at 50% of the desired torque limit (LD_Soll).'

Ulf, or Rainer, have already experimented with the LD temperature limit.

To both of you, or Rainer, since Ulf is on vacation:
'If the fuel injection quantity is being actively adjusted due to the overheat protection, or if the power is being reduced due to an excessively high LD temperature, would I be able to see this information on VAG-Com?'

The driver's desired settings must remain unchanged, the torque limitation must stay the same, and the smoke emission should not exceed a certain level, even if the air mass is low due to a reduction in LD (likely referring to a specific system or component). How can I check the active cooking protection?
What is the LD_Soll?
What would happen if the water temperature is too high?

Maybe something isn't quite right here.
If the MSG is actively lowering the LD, there must be a reason for it.

I'm going to threaten the STG tonight:

Good idea, something like that might work on my Alfa .

Best regards, Jochen.

Okay, here's something else to look at:



Here's a scan of Block 11 over a slightly longer period. The area near the left green vertical line is interesting. The motor was in sliding mode here, with a duty cycle of 25% and boost pressure close to zero.
The boost pressure generally follows the target value quite well, until you reach the area on the right with the two red and one green vertical lines. This was a full-throttle test.
The boost pressure builds up and is then reduced again, which is the actual problem. After the switching event, the boost pressure rises again towards the target value, even with a significant overshoot.


Here are the measured temperatures. The measured value for the intake air temperature is at least 7 to 8°C too low, as determined by comparing it to the current ambient air temperature at engine start.
I can't really say whether the value itself is plausible.


Here's another attempt at full power, which ended in a limp mode. Interestingly, the duty cycle goes up to 92% in limp mode; does that mean anything?


Here's the fuel injection amount during a full-throttle test.

Jens.

Hello,

I think the 92% figure is simply MSG's attempt to reduce LD as quickly as possible.

See Jochen's post:

Quote:

Small PWMs mean VTG is closed -> high LD. Large PWMs mean VTG open -> smaller LD

(oops, I've now gotten myself involved in the PWM discussion ).

Roger wrote:

I think the 92% figure is simply MSG's attempt to reduce LD as quickly as possible. (oops, I've now gotten myself involved in the PWM discussion )

Hm,
"However, that doesn't align with the air-fuel ratio in idle/glide mode, which is 25% in that case, and there's no boost pressure required."
Secondary theater of war discussion

Regards,
Jens.

Hi,

Here's a log from my car for comparison, same model, same engine, etc.


Could you please log the temperature while running it up to the emergency mode?
And please provide the peak values for LD (light intensity) and temperature.
Is the exhaust flow to the turbo 100% sealed?

Regards,
dieter

Regarding the temperature sensor:

Could someone please check the part number and approximate price of the item at Onkel?
Is it also available in regular retail stores?

Regards,
Jens.

Hello everyone,

die 92 % sind IMHO nur der Versuch des MSG, schnellstens LD abzubauen.

Absolutely correct interpretation.
In the LL (low load), the engine attempts to build up the LD (load demand) as quickly as possible or to maintain the target LD. Therefore, the VTG (variable geometry turbine) is almost completely closed in the LL. That was exactly the key point that I stumbled over.

In emergency mode, you therefore have 92% PWM, because no LD should be built up here.

Interestingly, the attempt ended in failure.
Hier versucht das MSG krampfhaft LD aufzubauen: LD_Soll ist maximal, das Tastverhältnis so um die 25% (kann ich nur schätzen), also die VTG eigentlich geschlossen, aber der LD baut sich nur unzureichend auf. DThe next episode: Emergency mode.

I also find it interesting that in the first log, the control and LD setup are excellent, but a few seconds later, it becomes sluggish again, and then in the last acceleration, it's working well again (Log 1).

If I can ensure that the intercooler piping is always airtight, I'd like to focus on the physical connection to the N75 valve next.
I now believe that the PWM signal may not always be reaching the valve correctly, or that the valve is somehow interfering with the signal.

The control system attempts to regulate the output appropriately, but the actuator does not respond linearly. Therefore, the duty cycle often appears 'strange.'
The over-revs are within the IMA's acceptable range and are to be expected when you suddenly accelerate to full throttle.

Best regards, Jochen.

Jochen_145 wrote:

I now believe that the PWM signal is not always reaching the valve correctly, or that the valve is doing something strange with the signal. The control system attempts to regulate the output appropriately, but the actuator does not respond linearly. Therefore, the duty cycle often appears "strange." The over-revs are within the IMA's acceptable range and are to be expected when you suddenly accelerate to full throttle. Hi Jochen

Hello.

That's exactly what I initially suspected, which is why I asked those questions earlier.

Roger wrote:

Wurde das Ladedruckregelventil eigentlich schon geprüft ?

Roger wrote:

@Jens: Regarding the LD control valve: Does the VTG, when in the default position in MWB 11, exhibit a significant upward movement until it reaches its upper limits (attention, fingers!)?

Regarding the N75 itself:
I bought it just a few days ago.

Regarding the VTG (Variable Turbine Geometry) linkage during engine start:
He does it as theoretically required.

*grmpf* This problem is really a tough nut to crack, I want my old diesel engine back .

Jens.

Okay, I understand. Please provide the text you would like me to translate from German to English. I will only provide the translation.

Okay, I understand. Please provide the text you would like me to translate from German to English. I will only provide the translation.