LMM and Diode Replacement: Troubleshooting Guide

Hello,

The car is an Audi A4 2.5 TDI AKE (with a chip tuning).

Ich habe eine Frage die ich bisher mit der Suche noch nicht beantworten konnte. Ich habe ein paar Logfahrten gemacht und mir mal die Rußbegrenzung angeschaut. Laut Vagcom ist die Rußbegrenzung (IQ MAF (smoke)) eigentlich immer der niedrigste Wert gegenüber IQ driver, zumindest bei Vollgas in allen Drehzahlbereichen. Bsp.:

2800 RPM
IQ Driver: 79.4 mg/R
IQ rpm (torque): 50.2
IQ MAF (smoke): 64.0

In this forum, I read that something might be wrong. Based on my feeling, I would say that it reacts a bit slower and is a bit weaker in the higher RPM range, although that could also be my imagination.

Habe mir dann mal die MAF - Werte angeschaut. They are included.
U/min: Revolutions per minute
Maf: (Assuming this is an abbreviation, a possible translation would be) Manufacturing Automation Framework. However, without more context, it's difficult to be certain.
1949: 686
2274 977
2598 1000
2946 1000
3294 887
3619 891
3921 863
4199 841
4431 788
4640 711

The values actually look good according to VAGCom (they should be above 750). My car is chipped, which is why I'm asking: Are the values still okay from 3294 onwards, or are they a bit low? And is the drop from 3619 normal?

LMM is a Hitachi brand (which is supposed to be more durable than the competition from Bosch).
I actually wanted to install a diode and check what the values would be like. Has anyone had any experience using a diode with an AKE (presumably a specific type of device), and can tell me if it works or if it leads to an error?
'If so, I would be interested in the pinout diagram for the Hitachi connector. While I can identify the cable colors in the schematics I have, I can't determine which signal each wire represents. The pinouts shown in this article don't match my connector, which I've already tried.'

Okay, I think that's all for now. I would be happy if someone would reply to this thread. Otherwise, I wish everyone here a good night.

GRace wrote:

Laut Vagcom ist die Rußbegrenzung (IQ MAF (smoke)) eigentlich immer der niedrigste Wert gegenüber IQ driver, zumindest bei Vollgas in allen Drehzahlbereichen. Bsp.: 2800 RPM IQ Driver: 79.4 mg/R IQ rpm (torque): 50.2 IQ MAF (smoke): 64.0 In this forum, I read that something is wrong. :

Hi,

Did you overlook the torque limit (highlighted in bold above)?
That's probably the lowest it can be, so everything seems to be fine.

Have you read the technical article about the TDI principle?

Sorry, it took me a while to get back to you.


Hi,

@ulf, thank you for your answer . I have to admit, I hadn't seen it until just now.

If I understand the article correctly:

'While the IQ-Driver shows a higher value, the Motronic calculates the maximum permissible value based on the current operating conditions (= IQ rpm (torque): 50.2). And does it allow this 50.2 value to be reached if the soot reduction limit is not lower (= MAF (smoke): 64.0)?'

The IQ rpm (torque) value of 50.2 is calculated, among other things, based on the boost pressure. In a chipped (tuned) engine, both the boost pressure and the fuel injection amount are increased. Therefore, my car's value should be higher than the stock value, especially at this point (IQ rpm (torque): 50.2). Since the soot limit is never the lowest setting, I assume that the mass airflow sensor (MAF) is still functioning correctly.

Did I understand that correctly? If so, are there any benchmark values that show how much higher my IQ rpm (torque) is compared to the standard configuration?

bye, bye

YES.

If the Russian border is never the lowest value, then the LMM seems to be working correctly.

NO.

The torque limit is not calculated; instead, it is provided as a characteristic curve.
You can see that clearly when you give it a little gas while it's stationary (around 2000 RPM).
Then there's almost no boost pressure, but the maximum engine speed limit kicks in (and the engine then runs at the speed requested by the driver, as the lowest value).

m;

Ah ha, thank you for the explanation. Why is the driver request so high at 100% pedal position, since it can actually never be reached? Wouldn't it be enough to set the driver request to the maximum torque limit instead?

Is this intended as a safety margin, or is it determined by the accelerator pedal mapping, which is often modified by chip tuners to give customers the illusion of additional torque at the same pedal position?


How is the boost pressure actually calculated? The boost pressure value in the map is a target value. If the actual boost pressure is too low, the engine produces less power. Is this because the amount of air entering the cylinder is insufficient to optimally burn the fuel (resulting in more soot), or is it because the engine control unit reduces the fuel injection量?

Bye and have a nice weekend, even though the weather is so awful.