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Aftermarket ECU Base Timing (135 trigger tooth ABY)

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  • Aftermarket ECU Base Timing (135 trigger tooth ABY)

    Advance warning... I know very little on the technicalities of timing.

    I've read many of the threads on checking the base engine timing, with particular respect to using an aftermarket ECU... but just need validation that I've understood the process correctly.

    The engine is an ABY, running the factory 135 trigger tooth setup. It was originally running a 2Bennett mapped factory ECU, then I converted this to Autronic, and now I've moved to the ECU Master EMU Black. Throughout each of the three variations, the physical timing has never been touched - ie the belt has never been off... so it's just the ECU timing I need to validate.

    The three triggers seem to be setup OK in the EMU Black, but I believe I now need to check/confirm the base timing of the engine, and ensure I have the correct trigger angle set, so the engine and ECU are fully in-line with regards the ignition timing.

    From what I gather, if I lock the ECU timing at 0 degrees, and then check the timing with a timing light, if I have the trigger angle set correctly, then the timing marks should align and be spot on.

    If the timing marks don't line up, then I need to adjust the trigger angle until they do. This then aligns the ECU timing with the base engine timing, confirming TDC ignition... this is what I understand anyway. I've done this now, and it resulted in my trigger angle being set to 44 degrees. The two attached images show the timing when locked at 0 degrees in the ECU, and the trigger angle set to 44 degrees.... note, the timing marks do look sport on, but the angle the photos were taken makes them seem slightly out.


    A final clarification... which I just don't understand at all... I originally followed an EMU Master setup guide when configuring the 135 tooth Audi triggers, and it had the trigger angle set to 60 degrees, so this is where I started. I'd assumed this would be a definitive trigger angle needed based upon the Audi trigger type. At 60 degrees the engine started OK, and idled fine - but hasn't been driven as such yet... still in the early stages of mapping. However, it was subsequent reading that identified you should always check your base ignition timing.... which has brought me to the 44 degree trigger angle. What I don't understand is, how/why/can this trigger angle differ for different Audi 5 cylinder engines. I'd have to assume the document I was following was legit/correct. However, the document didn't specify an ABY 5 cylinder. Would other non-ABY 5 cylinder engines be any different?... or will the trigger angle be specific to the trigger setup used? In short, why would my trigger angle need to be set to 44 degrees, when another may be set to 60 when both using a 135 tooth trigger? Total mystery.....

    Under basic idle conditions, the engine seems to run fine at both 44 and 60 degrees, and in-between... confused!

    Cheers
    Mick





    Attached Files
    '94 S2 (RS2+ spec. Tarmac Rally Car)
    S2QuattroMotorsport

  • #2

    at 60 degrees it will overheat

    the value of 45 degrees is obtained using a stroboscope. Basemaps are not accurate, instructions are not accurate, don't rely on them too much
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    • #3
      Pulldown 1k need for DBW. I get primary trigger noise when I release the gas pedal. This can be seen in the rpm log when the engine is not running. Maybe it will not be superfluous on the stock TB.
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      • #4
        Brilliant!! - many thanks... I'll recheck my timing, and check the for trigger noise too.
        Cheers
        '94 S2 (RS2+ spec. Tarmac Rally Car)
        S2QuattroMotorsport

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