Coding 00004 at MSG 8A0 907 401 B

Hello everyone,

I stumbled upon something while browsing.

Code:

8C                                                                  4.2 - 111/2                                                                                   1Z-Motor                                                                         Fahrzeug raucht schwarz beim Beschleunigen und/oder unter Last                ________________________________________________________________                                                                                                Ursache: Einspritzpumpe ist zu fett.                                                                                                                            Serie  : Einspritzmenge korrigiert.                                                                                                                            KD     : Fahrzeug warmfahren, bis das Kühlmittel mindestens 85  C hat. Mit               V.A.G 1551 Meßwerteblock im Leerlauf auslesen (Funktion 0 und Wert            im Anzeigefeld 4 beobachten. Sollwert 15 ... 40. Ist der Anzeigewert            kleiner 15, Steuergerät codieren (Funktion 07) und Codierung 00004             eingeben. Die Codierung ist nur bei Steuergeräten mit Datenstand               D06, D08, D09 möglich.                                                                                                                                         Ist die Anzeige im Anzeigefeld 4 größer 15 und das Fahrzeug rußt               beim Beschleunigen, können Rußablagerungen in der Abgasanlage die               Ursache sein. Beim Beschleunigen kommt es zu einem kurzzeitigen Ruß            ausstoß. Fahrzeuge, die häufig im Stadt- oder Kurzstreckenverkehr               eingesetzt werden, neigen zu dieser Erscheinung. Die Rußablagerungen            sind technisch bedingt, es liegt kein Mangel vor.                                                                                                               Der Ersatz der Einspritzpumpe ist unbedingt zu vermeiden.

After some research, I found out that field 4 displays the fuel injection amount. The idle speed is read, and if the idle speed is too low according to the engine control unit (ECU), the actual injection amount is reduced through coding.
How is this achieved? Does this coding modify the fuel injection map?

Hi,

With the chosen coding, a different dataset (i.e., parameter fields) is typically selected within the control unit.
I'm not sure whether the fuel injection amount is being reduced or the turbocharger pressure is being increased. Did you ever have to check this yourself by logging the pump's control voltage and the boost pressure?

It would be advisable to first rule out other potential causes of soot buildup by checking the proper functioning of the turbocharger pressure control system and inspecting the intake tract for leaks (which can be identified by oil mist). It's also a good idea to read the error codes (e.g., ...). The injection start timing cannot be adjusted early enough, resulting in a "Russ" error and triggering the emergency program.

Best regards, Rainer.

Sure, here's the translation:

"Just a quick note:"
I don't have any problems with soot or anything like that.

I'm interested in the possibility of reprogramming. I didn't think that these very old MSG units, used in the older TDI (Bosch 0 281 001 185), would even have the capability of being reprogrammed. What I found there seems to prove it .

It's tempting to just try it out. Where can I find the previous coding?
Are there any other coding options known for this VW/Audi control unit, specifically part numbers 8A0 907 401 B or Bosch 0 281 001 185?