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Thread: Lean open loop when cold

  1. #1
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    Lean open loop when cold

    I have been working hard on re-tuning my 94 383 LT1 using EEhack and tunerpro and at this point am pretty happy with the results. I do have one issue I dont understand however. When I first start the vehicle, when it is cold, before it goes into closed loop, it runs very lean according to my wideband. Like 18 to 1 lean, in spite of the fact the open loop AFR is set to around 14:1. However once the 02 sensors start working, and I log it, all of my trims are within 2 to 4%. What tables can I utilize to try to fix this issue?
    Thanks
    Roy

  2. #2
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    Quote Originally Posted by Fastmax32168 View Post
    I have been working hard on re-tuning my 94 383 LT1 using EEhack and tunerpro and at this point am pretty happy with the results. I do have one issue I dont understand however. When I first start the vehicle, when it is cold, before it goes into closed loop, it runs very lean according to my wideband. Like 18 to 1 lean, in spite of the fact the open loop AFR is set to around 14:1. However once the 02 sensors start working, and I log it, all of my trims are within 2 to 4%. What tables can I utilize to try to fix this issue?
    Thanks
    Roy
    Adjust the open loop afr afr vs map table where the problem lies.

  3. #3
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    I can do that, but seeing as how where it is set at about 14:1 it is generating 18:1 A/F rations, I thought perhaps there was something else I should be looking at. Is it normal for it to be this inaccurate on modified motors?

  4. #4
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    Same here, cid not mange to find proper after start and/or warmup enrichemt tables/scalars. My is not that lean but still it is an issue. I run SD mode only.

    Best regards

  5. #5
    LT1 specialist steveo's Avatar
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    if your engine is running without much trimming, and you disable closed loop, your afr should be pretty close to its target. i doubt 18:1 is a real number. is that an average or just a peak?

  6. #6
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    Did you find a specific temp range that the lean is taking place.

    I had the same issue and managed to narrow it down between 40-44 *C.

    The tables that are most responsible is the end of injection target during warm up and the transient fueling tables are related too.

    There are some initial enrichment tables too, but they don`t help much about that specific issue.

  7. #7
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    I am having the same problem, mine is running rich instead of lean though. Are you injectors big enough ? Does it run lean at WOT ?
    Seems like you need a table that adjust the "choke" settings. I could never find that or figure that out.

  8. #8
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    Quote Originally Posted by Turnshredder View Post
    I am having the same problem, mine is running rich instead of lean though. Are you injectors big enough ? Does it run lean at WOT ?
    Seems like you need a table that adjust the "choke" settings. I could never find that or figure that out.
    "Choke" settings I have only seen in TBI systems. They only have effect for a few seconds after startup.

  9. #9
    LT1 specialist steveo's Avatar
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    there are tables for initial start enrichment in EEX you can play with, after that there are a bunch of pulsewidth adders vs temperature, which is basically choke

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