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Dwell table std and TFSI coils

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  • #16
    I'm glad I found this thread.
    And thank you le mans for sharing.

    For me the car has not been up to par since the mapping event and that has puzzled me.
    Fuel, boost and ignition angles are all fine but it seemed dull when boost came on.
    Then it hit me, it must be something about mapping on Race Ethanol (50-75%) vs the E85 I get from the pumps in Sweden.
    I have used the picture of the dwell table from the latest post as a starting point and now been out in the car starting to tune.

    I'm using MaxxECU so it looks a bit different.
    This is how the dwell setting it looked from mapping which evidently worked excellent then:


    I wanted the settings related to RPM I switched to "Time (table)" mode instead.
    And also made a 4th axis: MAP.
    So in the first picture the dwell is set from 0-100Kpa


    In this one the dwell is set between 100-190Kpa


    And in the last table the dwell is set between 190-260 Kpa


    Compared to before this has made wonders.
    Cruising and light/medium load is so much smoother and better!
    It seems the pump E85 really needs lot of dwell to work, might be water in the fuel as well, who knows.

    I've searched the web about dwell and I'm still not sure how far I can push these coils.
    It's the "Audi R8 Red-top coils" made by NGK.
    Does anyone on here know?
    Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
    http://www.garaget.org/?car=52877

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    • #17
      So I decided to go back to the 'Time (dwell time + adjustments)' since it was mapped that way and is far less complicated.
      I also remember reading somewhere that the 2.0T cars do not use RPM as a parameter for dwell, this might be wrong though.

      I landed on 2.75 for the cleanest running on idle and of course min/med/max load conditions.
      I see a peak of ~3.5 on max load.
      This is a high number but it seems to work the best, so I'll have to live with perhaps changing coils more often.

      I might go down from 0.6 to 0.55 spark gap on next spark plug change, this might allow me to lower the dwell.
      dwell_map_2.png
      Last edited by k.alle; 23rd July 2019, 20:11.
      Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
      http://www.garaget.org/?car=52877

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      • #18
        You don't need more than 2ms on low load.
        High load up to 3ms, everything else usually just makes heat only and damages the coils.

        If you have only a RPM x Voltage matrix then run 2.5ms at 14V. If you get misfire, try 3ms at higher RPM.

        Source: Experience
        http://tuner.ee - http://www.facebook.com/tuner.ee

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        • #19
          Thanks for that prj.

          Since my last post I have changed to Iridium plugs and 0.55 gap.
          I now use 2.4 ms @ 14 volt with the same good results as 2.75 on copper plugs.
          Peak dwell now at ~2.8-3 ms during full load.

          Requested dwell @ 2.4 ms usually translates to an actual dwell of 2.3 ms when looking at the logs or mdash.


          Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
          http://www.garaget.org/?car=52877

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          • #20
            Thread resurrection. PRJ, thanks so much for sharing your tuning experience with us novices. I found another piece of information on another excellent forum about these coils:

            The R8 coils do not need much dwell at all for most applications but they can be cranked up to produce really good ignition energy if needed. Be aware they pull significant current so your wiring needs to be capable.

            For most NA and mild boost applications they only need about 1.6ms at 14V - they are pulling about 8A already at that! At 2.5ms they are pulling about 16A each. They saturate at about 12.8ms pulling 18A.

            Here is the dwell table from the last time I used them in a mild turbo road engine ~1.4Bar.

            I'm currently using this dwell map on my RS2 running a Link ECU with factory turbo (running 1.5bar), factory spark plugs, intake and exhaust with R8 TFSI coil conversion and it works flawlessly (touch wood).

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