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Thread: Ambient air or intake air temp modifier

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    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Ambient air or intake air temp modifier

    Which one does our computers use to change the fueling according to air temp? I'm assuming the ambient (or battery) temp, since T1's didn't have IAT sensors.

    If so, what is the table to modify that fueling? I had my fueling set pretty well, but now that it's dipping into the 30's at night, it's running lean, particularly in part throttle boost. Almost a full point leaner at WOT, PT it's in the high 12 AFR's in boost.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  2. #2
    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
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    Re: Ambient air or intake air temp modifier

    Stock T1's don't modify the fueling for temperature, except on cold start-up. That's probably why it's lean. Cold air is much desner than hot air.

    Modified cals can be setup to 'see' the IAT if it's wired in.
    https://db.tt/SV7ONZpQ
    Rob Lloyd
    '89 Daytona C/S

    2.5 T1 Auto
    13.24 @ 100.5mph
    NHRA #3728 AF/S

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  3. #3
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Ambient air or intake air temp modifier

    Sooo is that part of why they were set rich from the factory? So they don't lean out in cold weather, since they don't modify fueling from intake/ambient temps?
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

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    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
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    Re: Ambient air or intake air temp modifier

    Quote Originally Posted by Force Fed Mopar View Post
    Sooo is that part of why they were set rich from the factory? So they don't lean out in cold weather, since they don't modify fueling from intake/ambient temps?
    Exactly correct. At least, that's my assumption.

    An alternate way to look at it is that they assumed the coldest temp possible in the T1 cal, and calibrated to that. The effect is that you run richer than necessary when its hot, but that gives some protection against knock. With a performance hit, of course.

    The T2 cals are calibrated to the warmest temp (where the IAT correction is 0). And the IAT corrects to the current temp. The T2 should then have better A/F control.
    https://db.tt/SV7ONZpQ
    Rob Lloyd
    '89 Daytona C/S

    2.5 T1 Auto
    13.24 @ 100.5mph
    NHRA #3728 AF/S

    boostbutton.com
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