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Thread: Wide band far cold start up

  1. #1
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    Wide band far cold start up

    Using a wide band what is a good AFR at cold start up? Right now I’m at 10.5 AFR on my WB 02. I know its to rich but what am I looking for??
    94 c2500 383 TBI

  2. #2
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    Quote Originally Posted by C2500 View Post
    Using a wide band what is a good AFR at cold start up? Right now I’m at 10.5 AFR on my WB 02. I know its to rich but what am I looking for??
    94 c2500 383 TBI
    Most TBI are set to start rich from cranking fuel before leaning out.

  3. #3
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    Quote Originally Posted by notime2d8 View Post
    Most TBI are set to start rich from cranking fuel before leaning out.


    Yes but it stays there till it goes into CL....

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    10.5 is too fat, I'd need to look at some of my old logs but from memory I think I was around 12.5-13.0 cold.

  5. #5
    Fuel Injected! dktool's Avatar
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    What does it do if you put it in gear, does it lean out some or stay 10 - 11 ? (in CL)
    Dean

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    Quote Originally Posted by dktool View Post
    What does it do if you put it in gear, does it lean out some or stay 10 - 11 ? (in CL)

    Dean, as soon as it goes in CL it leans righ out and it right at 14.7..I drove it and runs good and except for it going real lean on WO throttle nad stumbles a bit when driving slow then just pushing the gas down just a bit other than that it runs good...This is why I sent the chip back to Ed at FastChips to adjust..Yes its better but he said he never had one do what mine does..
    Last edited by C2500; 01-17-2018 at 12:04 PM.

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    Quote Originally Posted by C2500 View Post
    Dean, as soon as it goes in CL it leans righ out and it right at 14.7..I drove it and runs good and except for it going real lean on WO throttle nad stumbles a bit when driving slow then just pushing the gas down just a bit other than that it runs good...This is why I sent the chip back to Ed at FastChips to adjust..Yes its better but he said he never had one do what mine does..
    Sounds like he needs to add some AE to the mix.

    Even my Vortec MPFI OBD2 engine runs about 11-11.5:1 on a 40F cold start and stays that rich for a good 45 seconds to a minute until it goes into closed loop.

    My direct injected M56S factory AFR targets were in the 10s on a cold start warmup and it is spraying fuel directly into the combustion chamber.

  8. #8
    Fuel Injected! dktool's Avatar
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    Quote Originally Posted by dktool View Post
    What does it do if you put it in gear, does it lean out some or stay 10 - 11 ? (in CL)
    I asked this because mine initially cold starts fat but if I put in gear (increased load) it leans out some. This is prior to going closed loop.
    Dean

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    Dean, Never put it in gear when it was cold...

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