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Thread: 2.0 FSI Poor idle when cold

  1. #171
    Join Date
    Apr 2021
    Location
    CZ
    Posts
    12
    Users Country Flag

    Do you get stratified mode when you cruise along at part throttle, if you log your AFRs? Or just at idle?
    No at all. OEM NoX sensor was busted the time i bought the car. It sometimes reported plausible signal so engine rarely switched on stratified but sensor was already giving his goodbyes.

    I gave chance to sensors from China (DIY, cut cables, solder, heatshrink) but it turned out to be a mistake. One sensor came with broken heater another one was giving totally wrong data etc.

    You can look at pictures here (posts from Maro )
    https://bit.ly/3fmoXDB



    Right now i have this chinese sensor screwed in exhaust, 2 CANbus cables cutted and rerouted under passenger's footwell. 2 cables from NOX ECU 2 cables to MED ECU at your fingertips. MITM with Arduino is much easier this way. Power cables are left untouched in order to pass NoX sensor heater checks.
    I'm able to generate canbus frames and see corresponding NoX sensor voltages (O2 part) and NoX concentrations.
    I always end up with
    17441 - Sensor for NOx (G295)
    P1033 - 002 - Signal too Low
    So i guess i send signal with incorrect range (lower, upper threshold) or signal needs to reflect real drive conditions (plausibility check is not passing).

    I am not keen on solving this with "emulator" approach. Reflashing ECU with "cured" firmware is much better then hiding arduino behind passenger's compartment
    At worst, sacrificing stratified mode is also acceptable. For 2.0 engine with 4x4 8 liters / 100 km (29,4 US mpg) is not bad at all.
    Last edited by maro; 27-05-2021 at 07:07 AM.

  2. #172
    An update - I've been working with Maro offline as I have had some trouble posting replies on this forum.

    I have managed to get stratified mode working at low load driving without NOx sensor, cats or EGR.

    Seems to work okay, the odd misfire but will report fuel economy difference after this tank is empty.

  3. #173
    Join Date
    Jun 2021
    Location
    Melbourne
    Posts
    2
    Gday, have the exact same model mk5, ran around in circles for ages chasing this issue and in my case jade zero faults on vcds. Ended up cleaning the dreaded intake valves and the issue disappeared completely.

  4. #174
    Join Date
    Mar 2009
    Location
    Goulburn NSW
    Posts
    180
    Thread Starter
    This is very neat.

    Is the Arduino code available?

  5. #175
    Update:

    Maro and I have been doing a ton of work on this the last 6 months - he has now disabled his NOx system completely as I did through editing the ECU ROM. I have reverted to homogenous only as I was having too many misfires (probably my intake valves are a mess).

    There's a few fields you need to do to turn off NOx and have the car run stratified.

    1. set CWSKR to 0 (This kills NOx diagnostics from stopping stratified mode)
    2. set most of the middle bits off on CWNLKO (check FR compared to your bin)


    Also - to turn off that rough as hell cold start catalyst heating you can set TKHMX to 0.

    For anyone reading this with 1.6FSI I have made a pretty massive definitions file here:

    Golf 5 1.6 FSI - basic map for 03C997056M
    Last edited by drbluetongue; 22-12-2021 at 11:49 AM.

  6. #176
    Join Date
    Mar 2009
    Location
    Goulburn NSW
    Posts
    180
    Thread Starter
    That is great work - now I need to learn how to read and write the map - any pointers on where I can find out how todo it /what I need?

  7. #177
    Yes, I currently use a Kess v2 clone from AliExpress. It works awesome, does the checksums for you and writes changes in about 15 minutes - Maro had issues with the 2.0 FSI with MPPS v16 (a cheaper option) so recommend Kess v2 for sure.

  8. #178
    Join Date
    Mar 2009
    Location
    Goulburn NSW
    Posts
    180
    Thread Starter

    Sweet thanks for that - looks like I'm off to spend more money

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