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Switchable Chip Variant in MSG

 
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RazsmithII
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Post01-10-2004, 21:42    Subject: Switchable Chip Variant in MSG Quote

Hello, TDI community.

First of all, I'd like to commend this forum. I've been observing it for some time, and it seems to me that the initial test is truly 'difficult' enough to keep out those who just want to talk nonsense.

Now, regarding my problem or request:

I received an Oettinger chip as a gift for my AFN (yes, you heard that right. Due to delivery problems, a friend of mine received the chip twice...).

Since my G3 AFN has almost 200,000 km on the odometer (but has always been driven very carefully), I plan to implement the tuning chip as a switchable option, allowing me to switch between the tuned chip and the original chip.
As I've already read, it seems this is quite possible (Stefan apparently did it in his Sharan...).
Unfortunately, I haven't found anything in the forum itself, even after an extensive search icon_confused.gif.
Can this be achieved with a multi-dip setup, or only through custom-built control electronics?

I am grateful for any advice!

Best regards from Freiburg, Nico!
Can the chip be easily switched on or off while the vehicle is in motion?


Translated on 13-09-2026, 20:38.
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Marco
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Post01-10-2004, 21:52    Subject: Switchable Chip Variant in MSG Quote

Hello,

Normally, the original ROM and the modified ROM are housed on a small circuit board. This board is then inserted into the socket of the original ROM in the engine control unit (ECU). Switching between the two ROMs is then done simply by switching between the two chips. This means that the chip itself will not be switchable. I'm afraid I don't know if there are now ROMs that contain both images and only switch the addressing of the ECU.


Translated on 13-09-2026, 20:40.
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RazsmithII
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Post01-10-2004, 22:07    Subject: Switchable Chip Variant in MSG Quote

So, in simple terms, I need twice the storage space on the EEPROM.
Thank you in advance for your answer.
I'm looking for a simpler option that includes both the original and the tuning chip.
I'm thinking of building it myself, and I'm approaching it with a very optimistic attitude (I'm a mechanical engineering student with an electronics background, so I have some experience!).


Translated on 13-09-2026, 20:41.
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Marco
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Post01-10-2004, 22:38    Subject: Switchable Chip Variant in MSG Quote

No, you need the circuit board to switch between the two ROMs. The other thing was just an idea on my part. It's also possible that there are now completely different methods for switching between them (I'm unfortunately not knowledgeable enough about the subject to say more). Just wait a little longer and see if any more answers come in.


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wolfi_b
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Post01-10-2004, 23:04    Subject: Switchable Chip Variant in MSG Quote

I once read in a chip tuning forum that something like that can be realized with an EEPROM that is twice as large. However, there might also be switching boards available icon_question.gif.
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ulf
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Post02-10-2004, 8:12    Subject: Switchable Chip Variant in MSG Quote

wolfi_b wrote:
I once read in a chip tuning forum that something like that can be achieved with an EEPROM that is twice as large. However, there might also be switching boards icon_question.gif
available.
That would also be my "second-best" solution if I couldn't achieve satisfactory results with speakers.

As far as I know, chip tuning with TÜV approval is always offered as a one-way solution (meaning it cannot be reverted to the original performance), while many tuning boxes can be switched on and off.
If this option is not available, then it is a deal-breaker for me.

Why don't CT devices with TÜV certification have switchable taps?
Or are there such offers available now?
Gruß Ulf
_________

MG4 Electric


Translated on 13-09-2026, 20:43.
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Jan6K

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Post02-10-2004, 8:30    Subject: Switchable Chip Variant in MSG Quote

Hi,

If you use an EPROM that is twice the size, the most significant address pin naturally becomes the switch. If it's set to 0, the MSG sees the lower half of the memory, and if it's set to 1, it sees the upper half.

If you do this in a production environment, all sorts of things can happen – either nothing at all, because code that was identical was just executed, or it simply breaks down because it's being thrown from one piece of code to another at a completely random point.

I could imagine that it might work if the two EPROMs only differ in the characteristic curves, and not in the program code. However, even then, I can foresee potential issues like fallback behavior, because the program might still have "old" values in the registers that no longer correspond to the new characteristic curves (imagine switching during a characteristic curve evaluation...).

That's exactly where I would see the reason why one can't do something like that.

Best regards,

Jan.
1Z5 CFHF / AHB H4D


Translated on 13-09-2026, 20:45.
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Rudi
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Post02-10-2004, 12:06    Subject: Switchable Chip Variant in MSG Quote

So...
Typically, only the characteristic curves are modified. When switching during operation...
It is possible to operate [a vehicle] - as some people do, for example, when driving in a modified section of a speed limit zone.
to a 'jump' in the support point values, which is caused by...
to what extent the regulatory process collaborates with the support centers.
It handles well (I wouldn't rule out anything from 'nothing' to emergency mode).

If switch bounce and other disturbances, which are transmitted through the cable, occur...
I wouldn't put a control unit inside something like a mobile phone or a cell tower... I don't know what else.
ausschließen, dass sich das STG völlig auf die Klappe legt icon_eek.gif. M'an benötigt also' translates to:

'an therefore needs' or 'an thus requires'.
eigentlich ein kleines Platinchen mit Entsörmaßnahmen. DThe whole thing needs to be translated.
Vehicle suitability (shock, vibration, temperature) must be ensured and the components must be housed within the control unit.
Demonstrating the operational safety of such a modification is not cheap.
and doesn't seem to be in high demand from customers.

Best regards, Rudi.


Translated on 13-09-2026, 20:47.
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RazsmithII
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Post02-10-2004, 16:34    Subject: Switchable Chip Variant in MSG Quote

Well, then that would probably be the end of it for me! icon_mad.gif
First of all, because I have very little knowledge about the precise chip addressing.
like an African tribe, and secondly, I think that...
This implementation would exceed both the cost and time frame.
I have also already thought about the problem of switch bounce.

Unless someone has a better idea...


Translated on 13-09-2026, 20:49.
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Rudi
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Post02-10-2004, 17:33    Subject: Switchable Chip Variant in MSG Quote

The principle is there: http://www.chiptuningforum.com/phpbbchip/viewtopic.php?t=62
described.
I would at least 'de-bounce' the switch using an RC circuit.
and also not switch to the backup system under load.

Best regards, Rudi.


Translated on 13-09-2026, 20:50.
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