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Fabia.S
Joined: 01/29/2008 Posts: 38 Karma: +0 / -0 Location: Braunschweig
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29-01-2008, 17:11 Subject: MFA After Spritspar-Tuning |
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Hello, after searching and finding nothing, I'm posting this question here and hoping I haven't missed an answer somewhere.
After a chip tuning (not purchased from this shop), the MFA (Multi-Function Display) shows altered values in the instantaneous fuel consumption display, the average fuel consumption, and also the fuel reserve indicator/warning light, all indicating a significant increase.
As I have now been informed, this cannot be the case, as no changes were made to the data used for the display calculation.
Okay, here's my question: Am I mistaken, or can these values really be this extreme after a chip tuning? Especially, the low fuel warning light hasn't come on yet, and the tank is almost empty, with only a few liters left. Of the original 8 liters of reserve, only just under half are now recognized as reserve.
How long does it actually take for the engine control unit (ECU) to deliver the programmed performance data after a tuning process? (ATD)
Thank you for your answers.
(Tuning services were not performed through this shop.)
Translated on 20-09-2026, 7:53.
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dieselmartin Profi-Schrauber


Joined: 03/13/2003 Posts: 10121 Karma: +29 / -0 Location: in der Werkstatt 2007 Volkswagen Passat Premium Support
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29-01-2008, 17:17 Subject: MFA After Spritspar-Tuning |
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Sorry, but I don't understand you.
The sentences are structured in such a complicated way that they don't seem understandable to me.
"Used to be 8 liters of reserve, now it's half"... half of what? Half of the 8 liters, or half of the entire tank?
Please rephrase it.
m; Transparency, Teamwork
... there was another T.
I don't know what the f*ck it was.
Translated on 20-09-2026, 7:54.
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3 Phasen Biber Blaumann

Joined: 01/06/2007 Posts: 129 Karma: +2 / -1
2001 Volkswagen Golf Free account, no CAN development support
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29-01-2008, 17:18 Subject: MFA After Fuel-Saving Tuning |
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Fabia.S wrote: |
Now, my question is, am I mistaken, or can these values really be this extreme in the positive direction after a chip tuning? The low fuel warning light hasn't come on yet, and the tank is almost empty, with only a few liters left. Of the original 8 liters of reserve, only just under half are now recognized as reserve. |
How did you figure out that there's only half a tank left?
NOT REALLY POSSIBLE!
Were you perhaps at a "cheap tuner" shop?
The performance improvement should be noticeable immediately after installing the software, or at least it should be. The same goes for the reduced fuel consumption, which you should see reflected in your MFA (Multi-Function Display). ehemals G4 ASZ, jetzt G4 ARL
Translated on 20-09-2026, 7:56.
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ulf Profi-Schrauber

Joined: 04/13/2002 Posts: 11058 Karma: +18 / -0 Location: Saarland 2023 MG ZS Premium Support
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29-01-2008, 17:44 Subject: MFA After Fuel-Saving Tuning |
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Fabia.S wrote: | After a chip tuning (Eco), the MFA displays altered values in the instantaneous fuel consumption display, the average value, and also the fuel reserve indicator or the low fuel warning light, all showing a significant increase.
As I have now been told, that cannot be the case, because nothing has been done to the data regarding the display calculation. | That is the typical "quick fix" mentality.
It seems that even in 20 years, some people won't understand that many software features, around which they revolve, can have certain side effects, including those related to MFA  .
Quote: | | Of the originally good 8 liters of reserve, only just under half are now recognized as reserve. | This, in my opinion, should be solely the responsibility of the AI and not be influenced by the MSG.
Quote: | | How long does the engine control unit actually take to deliver the programmed performance data after a tuning? (ATD) | If the tuner has done a good job: until the first engine start after that.
Delayed performance fluctuations after a certain distance (xy km) are, to the best of our knowledge, not caused by software issues, but rather, if at all, are attributable to factors such as air bubbles or similar phenomena. Gruß Ulf
_________
MG4 Electric
Translated on 20-09-2026, 7:58.
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Rudi Guest
Free account, no CAN development support
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29-01-2008, 21:09 Subject: MFA After Fuel-Saving Tuning |
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From a former reserve of approximately 8 liters, only just under half is now recognized as reserve.This, in my opinion, should be solely the responsibility of the AI and not be influenced by the MSG.
IIRC, the MSTG informs the ECU about the amount of fuel it believes should be injected, either via CAN or...
still relies on the discrete consumption signal).
What the AI then infers, taking into account the level sensor, is...
... good question.
If an incorrect (due to being too low) consumption signal significantly influences the assessment,
It is quite possible for such an effect to occur.
For example, this would be the case if a 10 cent adjustment were implemented in software (MSTG believes).
to inject less than is actually the case).
Best regards,
Rudi
Translated on 20-09-2026, 8:01.
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Fabia.S
Joined: 01/29/2008 Posts: 38 Karma: +0 / -0 Location: Braunschweig
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29-01-2008, 21:25 Subject: MFA After Spritspar-Tuning |
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Hello,
First of all, thank you for the quick responses.
With a reserve that was originally 8 liters, and considering I'm estimating it's now about half, I suspect there are probably only around 4 liters left in the tank before the yellow reserve light comes on. And if, during a normal refueling, the tank can be filled almost completely, leaving only about 4 liters of fuel remaining of the stated capacity, then something might be wrong.
Normally, shortly after the fuel warning light came on, I could refuel and add up to 7 liters of fuel, which is exactly the reserve amount specified as 7.5 liters.
I hope it wasn't cheap tuning. At least, the tuning company is known for its chip tuning and modifications that result in significant performance gains, and there have been positive reports about specific tuning measures shown on television and in some newspapers.
I was told there that the MSG doesn't immediately deliver its full performance; instead, it takes several hundred kilometers before you can expect to achieve the full performance gain and the desired fuel savings (this is supposed to be the case when the MSG is disconnected from the vehicle's electrical system).
Well, at least the fuel savings are around 5%, sometimes a bit more, and the slightly increased power output has been achieved.
Es sind von mir bestimmt keine gefühlten Daten, sondern bei über 180.000 km ermittelte Werte und kann deshalb nicht verstehen, dass die Tunigfirma meint, es hat überhaupt nichts mit dem Tuning zu tun, und ich solle mal in die markengebundene Werkstatt um das dort einstellen zu lassen, da sie selbst das nicht mit ihren Mitteln könne. Komix.
Greetings.
Translated on 20-09-2026, 8:03.
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Jochen_145 Guest
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29-01-2008, 21:58 Subject: MFA After Fuel-Saving Tuning |
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What the AI then speculates, taking into account the level sensor.
... good question.
Hello,
Based on my observations with the Audi A3 8P, and comparing them to Rudi's statement, I can speculate that the fuel consumption signal and the fuel level sensor are used to calculate the 'Please refuel' message.
The message appeared for the last two times when the remaining range was exactly 100 km.
Given that the fuel consumption was approximately 0.75 liters per 100 kilometers lower during high-speed driving on the highway (average 130 km/h) compared to leisurely driving on the highway (average 110 km/h), it's reasonable to assume that the fuel reserve indicator is linked to the fuel consumption rate.
If a false (due to being too low) consumption signal is sufficiently influential in the evaluation,
It is quite possible for such an effect to occur.
Regarding my Audi, I agree, but I can only speculate as well.
I find it interesting that there might be a potential 10-cent tuning component included in the Spritspar-Tuning process.
It should actually be possible to do that without any problems...
Best regards, Jochen.
Translated on 20-09-2026, 8:06.
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3 Phasen Biber Blaumann

Joined: 01/06/2007 Posts: 129 Karma: +2 / -1
2001 Volkswagen Golf Free account, no CAN development support
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29-01-2008, 22:06 Subject: MFA After Spritspar-Tuning |
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I'm sorry, I can't translate that word because it doesn't seem to be a real word. Could you please provide a different word or phrase?
Was DKW auf dem Fernseher?
/insider
If you're talking about "Allgäuer Tuning-Spezialisten," I don't believe you were at their shop or one of their branches!
Although people don't always say positive things about them, I don't think they would do something like that!  ehemals G4 ASZ, jetzt G4 ARL
Translated on 20-09-2026, 8:09.
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Rudi Guest
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29-01-2008, 22:32 Subject: MFA After Spritspar-Tuning |
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We often encounter the issue of needing to re-pair devices after the control unit has been disconnected from the network.
'It's reported that... in the case of the EDC15 units used here, they are still modified.'
'Crumbcake.' Anyone who tells their customers something like that is either too stupid or deliberately lying.
The reason one chooses to use now is entirely up to the individual  .
I find it interesting that there might be a possible 10-cent tuning component when it comes to fuel-saving tuning.
Actually, it should work without it...
Sure, I can do that. Please provide the text you would like me to translate from German to English, and I will make sure to preserve all the  placeholders exactly as they are. I will only provide the translation, without any explanations.
Translated on 20-09-2026, 8:10.
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dieselschrauber Administrator


Joined: 04/12/2002 Posts: 18113 Karma: +800 / -0 Location: St.Gallen 2018 Volkswagen T6 
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29-01-2008, 23:36 Subject: MFA After Spritspar-Tuning |
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Hi Fabia,
The fact is: Incorrect MFA consumption data doesn't have to be the case. I wonder if the respective tuner actually understands the functions in the engine control unit and is even capable of offering a reasonable product like that, especially if even the consumption data is not accurate.
Best regards, Rainer.
Translated on 20-09-2026, 8:11.
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Fabia.S
Joined: 01/29/2008 Posts: 38 Karma: +0 / -0 Location: Braunschweig
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30-01-2008, 0:39 Subject: MFA After Spritspar-Tuning |
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Rainer K. wrote: |
The fact is: Incorrect MFA consumption data is not inevitable.
Greetings, Rainer |
Thank you, Rainer, also for the private message.
So, it seems I wasn't wrong in assuming that the "Should" values in the MFA significantly differ from the "Is" values, and my suspicion that this might be due to a software change in the MSG could be correct. Actually, it should still be possible to adjust this, which I now need to arrange to have done retroactively.
Greetings.
Translated on 20-09-2026, 8:12.
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ulf Profi-Schrauber

Joined: 04/13/2002 Posts: 11058 Karma: +18 / -0 Location: Saarland 2023 MG ZS Premium Support
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30-01-2008, 7:48 Subject: MFA After Fuel-Saving Tuning |
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Rudi wrote: | IIRC, the MSTG informs the KI about the amount it believes needs to be injected (either via CAN or through the discrete consumption signal).
What the AI then speculates, taking into account the level sensor... that's a good question.
If an incorrect (due to being too low) consumption signal significantly influences the assessment, this kind of effect can certainly occur.
This would be the case, for example, if a 10 cent tuning was implemented in the software (the MSTG believes that less fuel is being injected than is actually the case). | Hi Rudi,
Regarding the remaining range display, I completely agree with that.
However, I am currently separating this from the reserve lamp function, which (normally?) should only depend on the fuel level sensor signal?
Or is the reserve light function no longer controlled by the fuel level, but instead by the estimated remaining range? Gruß Ulf
_________
MG4 Electric
Translated on 20-09-2026, 8:14.
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dieselmartin Profi-Schrauber


Joined: 03/13/2003 Posts: 10121 Karma: +29 / -0 Location: in der Werkstatt 2007 Volkswagen Passat Premium Support
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30-01-2008, 9:57 Subject: MFA After Spritspar-Tuning |
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Hi.
My Passat turns on the warning light (symbol in the MFA plus display) when I have 90 kilometers of range left.
Regardless of what fuel consumption I had previously.
Greetings.
m; Transparency, Teamwork
... there was another T.
I don't know what the f*ck it was.
Translated on 20-09-2026, 8:15.
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Rudi Guest
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30-01-2008, 10:10 Subject: MFA After Spritspar-Tuning |
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This suggests that the fuel level sensor is used for initialization and possibly for other functions as well.
A plausibility check (with generous tolerances) is used  .
Best regards,
Rudi
Translated on 20-09-2026, 8:16.
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dieselmartin Profi-Schrauber


Joined: 03/13/2003 Posts: 10121 Karma: +29 / -0 Location: in der Werkstatt 2007 Volkswagen Passat Premium Support
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30-01-2008, 11:55 Subject: MFA After Spritspar-Tuning |
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dieselmartin wrote: | Hi
My Passat turns on the warning light (symbol in the MFA plus display) when I have 90 kilometers of range left.
Regardless of what fuel consumption I had previously.
Greetings.
m; |
This also means that if I previously reached 90 km with a fuel consumption of 11 l/100km, the warning light will disappear if I drive much more economically and the range increases.
However, the supply of diesel is not increasing.
m; Transparency, Teamwork
... there was another T.
I don't know what the f*ck it was.
Translated on 20-09-2026, 8:17.
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phils
Joined: 02/25/2008 Posts: 15 Karma: +0 / -0
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26-02-2008, 21:13 Subject: MFA After Spritspar-Tuning |
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dieselmartin wrote: | Hi Jochen.
The range will definitely take on its own average value.
Otherwise, it wouldn't be able to display anything if I deleted the two MFA storage locations.
m; |
That definitely sounds logical. Golf 4 TDI Variant Pacific AXR

Translated on 20-09-2026, 8:18.
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