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Thread: Couple Idle and Starting Questions

  1. #11
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    Oct 2015
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    Quote Originally Posted by gpr View Post
    One more question unrelated question looking over my tune, at some point I put B3601 Ratio of Air to Fuel for Stoichiometry to 10 (this is the lowest limit even though e85 stoich is 9.7). I believe before I always had it set to 14.7, as the wide band was working on a gas scale anyway. Once I enable stft at idle, is this going to make it run extremely rich?

    I run mine at 10.0. If you don't, your air model is going to be WAY off. Use 14.7 for E0 14.6 for E10. 10 for E85. It will make your air models a lot closer to what they should be.
    No! It won't be too rich. They will add fuel to get the correct heat signature.

    Is AFR really used by the pcm? or does it base everything off lambda and eq ratio? Lambda and AFR are the same thing. You can tune in AFR with E85 and you'll look for a 12.5:1 (for example) just like you would with Gasoline.
    Lambda is just easier because the math is a LOT easier in your head for quick adjustments and covers ALL fuels.


    I replied in your quote

  2. #12
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    Jun 2009
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    A little update. I added fuel to B3201 initial fuel prime, B3604 Commanded fuel when cranking, and B3632 for once it fires up. This helped it fire up quick and stay running after it started, so that issue is fixed.

    However the hunting idle is still occurring when the engine is reved, or when coasting to a stop. What causes the hunting idle? In the attached screen shot you can see where I coasted to a stop, and the idle was hunting for a long while. Then once stopped I put it in neutral and reved it up. You can see where the idle remains too high until the spark starts adjusting and it settles down.

    So my two questions are:
    1. What causes the spark timing to remain constant for several seconds after the throttle is blipped?

    2. what is causing the hunting idle when coasting to a stop?
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