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Thread: G450 Adaptation - How To

  1. #11
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    Ok, thanks. I will try again tomorrow after the replacement EGT sensor is fitted. The short to plus fault is because the sensor is open circuit. There must be a pull-up to V+ as the sensor seems to work against chassis/ground. It seems misleading, to say "short to plus", but it looks like the ECU can't tell the difference as the sensor works between the signal line and ground.

    This sensor was working intermittently, throwing a fault saying "short to plus" and "implausible signal". There were two faults for the same sensor. I graphed the output from it and it was wandering all over the place between ambient and 900C at a physically impossible rate!
    I then tried to remove it and cut the cable to get a ring spanner over it. This is why it is now showing a constant hard fault as above.

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  3. #12
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    Ok, I've now got the car back from the garage. They reset the fault codes after fitting the new EGT-after-DPF but did not do an adaptation.
    Now with all faults cleared, The adaptation does appear to work, but when I opened the measuring blocks (before adaptation) the offset and differential pressure reading were different. This time it showed ~+7 diff and ~-12 offset.
    After performing the adaptation, nothing happened any differently to previous attempts (no confirmation of any kind), but this time after cycling the ignition, I got a diff pressure reading of zero and an offset of -7.86. Does this look like a sensible figure?

    On a slightly different tangent, still curious about what the adaptation actually does behind the scenes - Last year I had noticed that the offset seems to change regularly without any adaptation. Can anyone tell me if some ECUs do a baseline calibration every time the ignition is turned on - before the engine starts? If I was designing such a system I would to this. It makes sense to me as there can be no possible pressure difference without any exhaust pressure feeding the DPF, so is an ideal time to set the zero reference!

    Uwe - What I meant earlier about how VCDS responds was that any confirmation given to the user must be a program feature of VCDS. Given that there is no response from VCDS apart from the message "The controller accepted the login" does this mean that VCDS only sends the command to perform an adaptation and does not expect a response from the ECU due to the wide variety of different ones out there?

    Thanks for your input,
    Neil.

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  5. #13
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    Quote Originally Posted by neftronics View Post
    After performing the adaptation, nothing happened any differently to previous attempts (no confirmation of any kind), but this time after cycling the ignition, I got a diff pressure reading of zero and an offset of -7.86. Does this look like a sensible figure?
    Yes, I think so.

    Quote Originally Posted by neftronics View Post
    On a slightly different tangent, still curious about what the adaptation actually does behind the scenes - Last year I had noticed that the offset seems to change regularly without any adaptation. Can anyone tell me if some ECUs do a baseline calibration every time the ignition is turned on - before the engine starts?
    Unclear. Unfortunately, we don't have specs for what these ECUs decide to do and under what circumstances. But the fact that there's a way to force it to do it makes me skeptical that the ECU does this autonomously every time the ignition is turned on.

    Quote Originally Posted by neftronics View Post
    Uwe - What I meant earlier about how VCDS responds was that any confirmation given to the user must be a program feature of VCDS. Given that there is no response from VCDS apart from the message "The controller accepted the login" does this mean that VCDS only sends the command to perform an adaptation and does not expect a response from the ECU due to the wide variety of different ones out there?
    In this particular case, the the "command" is just a Login/CodingII, from which there is not feedback beyond an acceptance or rejection message.

    IMO, it would have been better if VW/Audi had implemented this function as an actual Adaptation or Basic Setting, but they didn't, and needless to say, we don't get a say in how they implement things.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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  7. #14
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    Quote Originally Posted by Uwe View Post
    IMO, it would have been better if VW/Audi had implemented this function as an actual Adaptation or Basic Setting, but they didn't, and needless to say, we don't get a say in how they implement things.
    Fair enough, you're only working with the information you can get hold of. I guess the dealerships are no better off than you are either!
    Quote Originally Posted by Uwe View Post
    In this particular case, the the "command" is just a Login/CodingII, from which there is not feedback beyond an acceptance or rejection message.
    Ah, this is what I wasn't sure about. Thanks for clearing that up.
    Quote Originally Posted by Uwe View Post
    Unfortunately, we don't have specs for what these ECUs decide to do and under what circumstances. But the fact that there's a way to force it to do it makes me skeptical that the ECU does this autonomously every time the ignition is turned on.
    -Uwe-
    True enough - I hope this is not the ECU with a failing EEPROM giving random offsets! So far the offset seems sensibly close to nulling out the static reading from the sensor. I will keep reading it periodically and see what it does between scans and ignition cycles. I'll report back if there is a pattern.

    Regards,
    Neil.

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