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Thread: Changing Stoich

  1. #1
    Tuner in Training
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    Aug 2017
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    Franklin, IN
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    Changing Stoich

    Hey guys, I'm in an odd situation because of the goofy wideband I bought. It's an AEM 30-5143 which displays in E85 AFR (5.6 - 11.9:1). I noticed that I can change stoich in HP, but the description confuses me a little. If I change this to 9.85:1 will anything else change in the tune? When I tune with MAF error, is changing stoich in the editor going to make the MAF error histogram display more accurately? Thanks!
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  2. #2
    Advanced Tuner coachcrow56's Avatar
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    Dec 2004
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    Longview, Texas
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    A lot of tuners change their AFR stoich to 14.4 to try and compensate for Ethanol at 10%. But your factory narrowbands are ALWAYS trying to adjust (and maintain) your AFR to 14.7.

    If you are running E85, do a lot of research and see what the AFR should be. My understanding is that if you change your AFR setting from Stoich, that it will affect your tune. Do some research---I am not really familiar with E85. I use 93 octane in East Texas.

    Search and you can find posts that will help you adjust your wideband. And use the posts in this section, titled Open Loop MAF TUNING. by Russ K. It is an excellent guide to tuning your MAF with a wideband.
    Last edited by coachcrow56; 05-13-2020 at 08:15 AM.
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  3. #3
    Advanced Tuner ZeroBoostBuick's Avatar
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    Aug 2008
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    If no one replies with a definite answer... hit up the fellas on the GM V8 (gen 3) sub forum. Most of the GM knowledge is there.