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Thread: TBI rich at start up

  1. #1
    Fuel Injected!
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    TBI rich at start up

    I've been working on my VE fuel tables over the last month and am getting the Commanded AFR to match the Actual AFR pretty closely when driving and also at warm idle. But when I first start up cold, the wide band is reading in the high 10's or low 11's when the commanded AFR is in the 12's.

    Setting the Open Loop - AFR Multiplier vs CTS from a negative value at cooler temp to zero helped a bit with the problem, but not sure what else to do get rid of this overly rich condition which I only see at initial start.

  2. #2
    Fuel Injected! PJG1173's Avatar
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    do you have an "open loop AFR vs. Temperature vs. Vacuum"?
    87 4Runner, 15" spring lift, 3" body, chevy vortec 355, 5.29 gears, 38.5x15.5x15" Boggers, 280hr, 16168625 running $0D
    93 S10, 36x12.5x15 TSL's, custom turbo headers, 266HR cam, p&p vortec heads, $0D Marine MPFI with 8psi boost.
    05 Silverado, 2' lift, 4" exhaust, Bully Dog programmer,

  3. #3
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    Quote Originally Posted by PJG1173 View Post
    do you have an "open loop AFR vs. Temperature vs. Vacuum"?

    Yes, I have that table. I am happy with the values in that table.
    The issue is that the actual AFR is richer than what the table says it should be.

  4. #4
    Fuel Injected! corvairnut's Avatar
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    Choke AFR will add fuel on top of the "open loop AFR vs. Temperature vs. Vacuum" and cranking fuel may also add to it. Im sure you know all that, but that is where I found my excessive fuel at startup.

    Ted
    Ted Brown
    Anderson, SC
    68 Corvair EFI
    61 Corvair Loadside Pickup (Future EFI)

  5. #5
    Fuel Injected!
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    Quote Originally Posted by corvairnut View Post
    Choke AFR will add fuel on top of the "open loop AFR vs. Temperature vs. Vacuum" and cranking fuel may also add to it. Im sure you know all that, but that is where I found my excessive fuel at startup.

    Ted
    How long would the choke tables be in effect? I thought they applied just for a few seconds. (like less than 10). I'm rich for a few minutes until the coolant temp comes up. A few minutes, not just seconds.

  6. #6
    Fuel Injected!
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    look at air fuel ratio vs coolent temp proble open loop, lots of times you can rasie this up a lot and have better driveablity till it gets in closed loop and save fuel too.

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