Adaptation channels- explained



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May 16, 2014
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I was given this explanation by a colleague on another forum (thanks Mydixadryl). The explanation was authored by Sean@Revo-Technik. Does "Sean", or his alto-ego exist on this forum? If so, many thanks for the words from an appreciative student!

The description is perhaps a little dated now (written May 2003), but it does provide a good insight into the fundamentals of adaptation channels. So a good learning tool - IMO.

It reads like back in the days of KWP2000, adaptation channels were a minor facility (I'm guessing). With modern vehicles however, it appears that adaptation channels have taken on a more central role (as the explosion in their numbers suggest)!


This will be an explanation of the adaptation channels in VW/Audi ECUs,
how they can be modified, and what effect they have on engine operating
Adaptation channels allow VW/Audi dealers to make minor tweaks to engine
operating parameters (e.g. engine idle speed adjustment). These
settings can be modified using the dealer's diagnostic equipment or
These settings are stored in a serial eeprom which means the settings
will not be lost if the ECU loses power. This is the same eeprom that
stores data that can change from time to time like diagnostic trouble
codes. This serial eeprom is different from the flash memory chip that
stores the main engine control program, and therefore changes made to
adaptation channels will not affect code checksums.

As an example, let us take a VR6 owner who is happy with the performance
of his engine but would like to have his speed limiter raised. There is
an adaptation channel that can be used to raise or lower the speed
limiter setting, and if there were a way to change this adaptation
channel then there would be no need for this owner to even buy a chip.
He would be able to continue running with bone stock ECU programming
with no worries about a dealership detecting a chip (since there is no
chip), and if he were particularly worried he would simply restore the
default factory setting before bringing the car in for service.

So, he connects to his ECU with VAG-COM, goes to adaptation channel 7,
and tries raising the speed limiter. But it doesn't work: the commands
that request the setting of new adaptation channel values have built in
limit checks and reject the new values. In this particular case, the
speed limiter related adaptation channel is effectively disabled since
the stock ECU programming limits the control range so that the only
valid value is zero (i.e. no change).

So the issue boils down to this: is it possible to change these adaptation
channels in such a manner that the original factory limits are bypassed?
There are two possible approaches. First, one can make a chip with the
preset adaptation channel limits extended to allow a larger adjustment
range. Second, one can bypass the VAG adaptation channel routines and
directly place the new adaptation channel settings into the ECU.
Changing the preset adaptation channel limits in a chip is the only
option for VAG group diesel ECUs, Magneti Marelli ECUs, and older Bosch
ECUs. These codes check the adaptation channel limits after the values
have been read out of the serial eeprom. Motronic 7 ECUs do not do this
check which opens up the second method.

Directly transferring the new adaptation channel values into the ECU
works by finding the RAM memory location where the ECU stores the
adaptation channel data and directly writing the changes to those RAM
memory locations. When the ignition key is turned off the ECU enters a
housekeeping mode where among other tasks the modified adaptation
channel data is written into the serial eeprom. This roundabout method
is required because memory writes directly to the serial eeprom are
Interestingly, this method will not work using the VAG mode protocol.
Write access is allowed to any ECU RAM location except those locations
that store the serial eeprom data. Someone at Bosch clearly knew about
this vulnerability and took measures to close this loophole. But for
some reason this loophole was left in the KWP2000 routines.
Each ECU code stores this adaptation channel data in different RAM
locations. To make this method work with any ECU one runs through the
following steps: 1) Establish communications with the ECU using KWP2000
mode; 2) Read data directly from serial eeprom (since read access is
allowed); 3) Search for this data in the ECU's RAM; 4) Write the new
adaptation channel settings to the RAM location; 5) Cycle ignition key
to have ECU transfer the new settings into the serial eeprom.
The KWP2000 protocol is not as reliable as the VAG protocol. Some cars
will have communications problems which often can be worked around by
pulling the instrument cluster fuse (make sure VAG-COM will be able to
clear you air bag DTC light before doing this!!!).

Using the KWP2000 protocol gives one the ability to change settings in
any VAG Motronic 7 ECU regardless of whether the ECU is stock or
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Nov 16, 2018
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I cant see adaptation channel after diesel scandal fix !!?!?!?! anyone could help me ?


Benevolent Dictator
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Jan 29, 2014
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May 30, 2018
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Is it possible to find the explanations of the adaptations of the A5 Front camera module.
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