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Thread: Irratic Start & Run

  1. #1
    Join Date
    Oct 2015
    Location
    Mason Michigan
    Posts
    14

    Default Irratic Start & Run

    I live in Michigan. The temp outside can vary 40 degrees from morning to evening. Every time I drive the car, I have to readjust the Cranking Fuel & After Start Enrichment. It runs beautiful once I dial these back in. I can't go to lunch in it, without my laptop. It's embarrassing. I have not messed with air temperature settings. Is that where I should start?
    94 Mustang GT, Holley HP EFI, blown 331.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,375

    Default

    Quote Originally Posted by Gkitsmiller View Post
    The temp outside can vary 40 degrees from morning to evening. Every time I drive the car, I have to readjust the Cranking Fuel & After Start Enrichment.
    Ensure the IAC Parked Position is properly programmed to allow enough cranking airflow.
    Ensure the idle speed screw is adjusted to achieve an IAC Position of about 5% at hot idle.
    Remember to perform another TPS AutoSet, whenever you adjust the idle speed screw on the throttle body.

    It runs beautiful once I dial these back in.
    Engine running has nothing to do with Cranking Fuel (after 400 RPM or whatever your "Crank To Run RPM" is)
    & After Start Enrichment % (temporary additional fuel decayed out over several seconds after engine startup).

    I have not messed with air temperature settings. Is that where I should start?
    The Air Temperature Enrichment % Table is one of the modifier tables you'll have to tune:
    http://forums.holley.com/showthread....3643#post63643 (Air Temperature Enrichment % Table Tuning - Posts #6 & #11)

    My previous Air Temperature Enrichment % Table:
    130.0% 127.0 . 123.0 . 120.0 . 117.0 . 113.0 . 110.0 . 107.0 . 103.0 . 100.0 . 97.0 . 93.0 . 90.0 . 87.0 . 83.0 . 80.0%
    -40°F ... -19 ....... 2 ..... 23 ..... 44 ...... 65 ..... 86 .... 107 ... 128 .... 149 .. 170 .. 191 .. 212 .. 233 .. 254 .. 275°F

    My updated Air Temperature Enrichment % Table:
    130.0% 124.0 . 119.0 . 116.0 . 113.0 . 110.0 . 108.0 . 105.0 . 103.0 . 100.0 . 98.0 . 96.0 . 93.0 . 90.0 . 86.0 . 80.0%
    -40°F ... -19 ....... 2 ..... 23 ..... 44 ...... 65 ..... 86 .... 107 ... 128 .... 149 .. 170 .. 191 .. 212 .. 233 .. 254 .. 275°F

    I attached an excellent Air Temperature Enrichment % table correction calculator to this post (from Paul Yaw at YawPower.com).
    Attached Files Attached Files
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, 100HP progressive dry direct-port NOS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, 160A 3G alternator, Optima Red battery, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3
    Join Date
    Oct 2015
    Location
    Mason Michigan
    Posts
    14

    Default

    Thank you. I will adjust the Air Temperature Enrichment % Table, and go from there.

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