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Thread: cold weather knock?

  1. #1
    Fuel Injected!
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    cold weather knock?

    Hey dumb question, got a 2.0 turbo sunbird running cpde 59 on the stock 7749 ecm. is there any reason as to why i would get knock in child weather vs hot? First cold days ive had wkth this sunbird, I'm getting knock retard of less than 5 between 4-10 psi area.. I back the timing back to single digits before i get rid of most of it, which makes no power....when it was hot i has low teens and very little to no retard. Cold should have opposite effect. I dont understand. A.f is around low 11's. Is there something I'm missing?

  2. #2
    Fuel Injected!
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    Have you checked for possible false knock signatures?

  3. #3
    Fuel Injected! steveo's Avatar
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    you're runnin' a bit lean (remember the colder the weather, the higher the requirement for fuel due to air density)

    you have a coolant temperature vs spark table pushing timing too far

    moisture is causing condensation in your distributor cap causing some fire to the wrong cylinder

    just some ideas

  4. #4
    Fuel Injected!
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    Joey, no i havent. How do i go about that.

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    Fuel Injected!
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  6. #6
    Fuel Injected!
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    I just drove home and did a log, Looking at the log its still all in about the same area. Got to 6.xx degrees retard at the worst point.

    A/f got to 11.8 MAX.. was generally around 11.4-11.6... I'd think that would be rich enough for it to be happy, I can always try richer?

    I dont really have any coolant temp table, I have manifold air temp correction table, and thats locked down to 1.6degrees across the whole board so that table is basically inop right now untill i set it up.

  7. #7
    Fuel Injected!
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    Ok. So i sat down to figure this out.... Got fuel down to 11.2 the whole way... Still knocked.... Backed timing off.. Still knocked..... Backed it off more .. Got worse. .. Did it again and even worse..

    So i said screw it and went UP with the timing about 12 degrees and it stopped and ran like a scalded dog!


    Is that nornal engine operation to act like that????

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