Notlauf möglich bei defektem LMM ? Frage zum Fachartikel. | Posts 16+

I need to revisit the topic of "determining the target boost pressure."
Based on Ulf's article, I thought the driver's preference was crucial:
"Quote from 'TDI: Basic Principles of Technology':"

Quote:

While driving, the electric throttle position sensor transmits the driver's desired fuel injection amount to the engine control unit (ECU). It first determines, based on the programmed boost pressure map, what boost pressure is required to burn the desired amount of fuel, and then begins to adjust the boost pressure to the corresponding value.

Sure, here is the translation of the text from German to English:

"Ende Zitat" translates to "End quote" in English.

Jan6K, on the other hand, wrote:

Quote:

The target boost pressure depends on the selected injection quantity (among other factors), NOT on the injection quantity that results from the driver's preference.

That seems contradictory to the article, as I already mentioned.
If it is indeed correct, then the following is from another...
Ulf's article is just as incorrect as the quote from the first article mentioned.
"Mass Air Flow Sensor: An expensive weak point in VAG TDI engines."

Quote:

... faulty mass airflow sensor ... Depending on the size of the mass airflow sensor (MAF) measurement error, fuel consumption will also increase: The boost pressure will continue to be regulated to achieve (theoretically) verschandeln combustion of the fuel injection amount requested via the accelerator pedal, while the actual fuel injection amount may be significantly lower due to the defective MAF sensor. In other words, the boost pressure is being set too high (relative to the actual amount of fuel being injected), which wastes unnecessary energy -> leading to increased fuel consumption.

The latter, therefore, logically cannot be the case.
I'm confused - who can resolve these contradictions?

Greetings, Klaus.

I don't believe any of that. A modified engine control unit might have artificially inflated the soot reduction values in order to reduce turbo lag.

When I suddenly accelerate, the target turbocharger pressure immediately increases. The time it takes to reach the desired boost pressure can vary.

We've just seen that errors aren't always entered where they are needed and would be recognizable by the MSG (Message System), for example, with the fuel injection start time.

Hi,

Don't take my word for it, but I'm pretty sure the injection amount is determined by the lowest of the three values (i.e., the Russian border, the driver's preference, and the torque limit). Since the required boost pressure depends on the current fuel injection amount, I would use the fuel injection amount as a control variable for it, rather than the driver's desired setting.

From the perspective of the turbocharger, the approach of prioritizing the driver's request makes sense, because the boost limit increases much more slowly than the driver's request (instantaneously, when the driver "steps on" the accelerator).

In case of doubt, I would therefore agree with the expert article and, consequently, with Ulf.

Best regards,

Jan.

I was now able to verify the plausibility of the control of the...
LD-Goals regarding driver preferences through a test drive.
understand.
The vehicle was an AFN, a Golf3, and in this case , it was in its standard trim.

With the LMM connector disconnected, at an engine speed > 2400 RPM...
The limit for Russian-made products is practically fixed at 26 mg per dose.
At 2500 RPM, the sequence (full load, thrust operation, full load) results in...
to corresponding extreme variations in the target LD (Load Drop).
while torque limitation and soot reduction remain constant.

You can view a short excerpt of the 3-8-11 log here:
/viewtopic.php?t=20738


Greetings, Klaus.