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Thread: fuel milage

  1. #1
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    Default fuel milage

    im new at this and was wandering what tables to use to adjust the gas milage

  2. #2
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    You can set the O2 Switch points table. Youll have to figure out what airflow mode you are in by seeing what your MAF airflow is at low loads then there is a table that shows you what airflow from the maf is what airflow mode.

    For me my low loads are about 0-24 then it ramps up steep from there.
    In thoes loads I set it to about 250 then went up slowly to about 350 at mode 24 then went up fast where it levels out at mode 40 at 450mv.

    Im pretty sure this just make the computer think that it is opertaing in a rich mode more of the time. Since the switch point from lean to rich is now at around 250mv it will think its running rich 25% more of the time or something like that.

    Only do this at low loads though becuase at high loads it might cause knock depending on your timing advance.

  3. #3
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    While we are talking about this, if you do the lean cruise thing with your O2 switchpoints. Will you get a negative LTFT when you are in the airflow modes where you lowered the O2 switchpoints?

  4. #4
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    Quote Originally Posted by cmitchell17
    While we are talking about this, if you do the lean cruise thing with your O2 switchpoints. Will you get a negative LTFT when you are in the airflow modes where you lowered the O2 switchpoints?
    Assuming your LTFTs were 0 or close to it at 450, they will go negative with lower switch points. How much is hard to say.

  5. #5
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    Quote Originally Posted by cmitchell17
    You can set the O2 Switch points table. Youll have to figure out what airflow mode you are in by seeing what your MAF airflow is at low loads then there is a table that shows you what airflow from the maf is what airflow mode.

    For me my low loads are about 0-24 then it ramps up steep from there.
    In thoes loads I set it to about 250 then went up slowly to about 350 at mode 24 then went up fast where it levels out at mode 40 at 450mv.

    Im pretty sure this just make the computer think that it is opertaing in a rich mode more of the time. Since the switch point from lean to rich is now at around 250mv it will think its running rich 25% more of the time or something like that.

    Only do this at low loads though becuase at high loads it might cause knock depending on your timing advance.
    im really confused by all this if possible could you take it a little slower i dont know how to get the load info and i dont know what tables you are talking about when your talking about the 0-24 and the 250 and so on sorry im alittle slow.

  6. #6
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    B4105 is the O2 Switchpoint table.

    Try these settings for the table.
    They should directly copy and paste to the B4105

    261.238441 261.238441
    266.426588 266.426588
    276.429877 276.429877
    287.653907 287.653907
    302.404520 302.404520
    321.800728 321.800728
    374.462112 374.462112
    509.998203 509.998203
    520.001492 520.001492

    B4107 is the closed loop mode table.
    Notice that anything over about 15-20% throttle puts you in closed loop mode 64. (Am I right here?)

    So in the modes under 60, they are in very light throttle low airflow conditions. The engine can run leaner in these airflows. Since it runs leaner it uses less fuel.

    The reason why the factory has this table set in the 450mv range is becuase the cat works the best at the air fuel ratio.

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