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Thread: Why does higher IAT go lean with SD tune?

  1. #1
    Tuner
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    Why does higher IAT go lean with SD tune?

    I have been trying to tune the VE table and yesterday I noticed my AFR went in the 17's after sitting still with the engine running because the IAT was 111°.
    Last night driving home when the IAT was 64°, the AFR was in the low14's to high 13's.
    Shouldn't it be the other way around? Seems like a colder denser air would make the car lean, and hotter air would make it rich!
    Is there a table for adjusting this?
    And how do you guys running SD full time get around this?
    LS1, magnacharger running 10psi, 90mm TB, LPE GT2-3 CAM, Dynatech LT headers, AFR 205 heads. Meth injection, 3.42:1 /A4 / 3000 stall muti-disc

  2. #2
    Tuning Addict WS6FirebirdTA00's Avatar
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    Bias adjustment. It is the overcompensation of the IAT calculations. You are right, in theory, but the computer moves the fueling too much. Just poor modeling.
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB

  3. #3
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    Quote Originally Posted by WS6FirebirdTA00
    Bias adjustment. It is the overcompensation of the IAT calculations. You are right, in theory, but the computer moves the fueling too much. Just poor modeling.
    Is there a table to tweak it? Or should I move the IAT temp in front of my AC vent?
    LS1, magnacharger running 10psi, 90mm TB, LPE GT2-3 CAM, Dynatech LT headers, AFR 205 heads. Meth injection, 3.42:1 /A4 / 3000 stall muti-disc

  4. #4
    Tuning Addict WS6FirebirdTA00's Avatar
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    I actually took out my IAT sensor and replaced it with a resistor lol
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB