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Thread: Question about the 14.7 EQ AFR table in 2002 CUSTOM O.S.

  1. #1
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    Default Question about the 14.7 EQ AFR table in 2002 CUSTOM O.S.

    The original map was filled with AFR ratios of all different ratios ranging from about 8:1 in the upper left to 14:1 through other areas. It varied wildly through out the map. My question is, Now that I have taken the chart and tuned it all to 14.7:1(except the last couple columns) Would it even run being so lean? I mean, it is idling at about 10.5-11:1 with my wideband the way the stock map is. This is almost exactly what is commanded. It runs good in 1 bar, but real rich. It also will not idle untill warmed up. I am just afraid that I will have major tuning problems with a 14.7:1 ratio through the entire map, when the "stock" map varied through out the map like It seems like it should. Should I use the stock map and lean it out? Thoughts?

    Any unput or experience on this? Did yours run decent?

    The only mods besides the turbos, are turbo headers, a comp .581 lift cam with 224 duration, and a lowerd (8:1) compression ratio. Any input?
    '71 chevelle
    Twin turbo ls1
    1000 HP 93 octane street car!
    96 lb injectors

  2. #2
    EFILive Distributor dfe1's Avatar
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    If I'm reading your question right, you're talking about the B3647 table. The instructions say to use 14.7:1 in all cells except those in the 95 and 100 kPa columns as A STARTING point. You have to give the engine what it wants, and the wide band will tell you that. Also keep in mind that the B3647 table is set up for rpm versus MAP whereas the stock table (B3605) is set up for ECT versus MAP. In the custom OS, the B3647 table is set up so you can absolutely control AFRs when the system is in open loop. It also enables you to run in "Semi Open Loop" where the system will function in closed loop, using short term fuel trims only, when an AFR of 14.63:1 is commanded. At all other commanded AFRs, the system functions in open loop. Hope this helps.

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    So if I want it to run in semi open loop, I chage it all to 14.63. Otherwise I leave it at 14.7?

    Why does it tell you to remap the entire map? Why can't someone just use the stock teble and tweak it as needed for any mods?

    Im I missing something here?? I don't see the logic in basically overwriting the ENITRE table that was already preadjusted from the factory??
    '71 chevelle
    Twin turbo ls1
    1000 HP 93 octane street car!
    96 lb injectors

  4. #4
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    Quote Originally Posted by nitrorocket
    So if I want it to run in semi open loop, I chage it all to 14.63. Otherwise I leave it at 14.7?

    Why does it tell you to remap the entire map? Why can't someone just use the stock teble and tweak it as needed for any mods?

    Im I missing something here?? I don't see the logic in basically overwriting the ENITRE table that was already preadjusted from the factory??
    It is a new custom table that is only used by the new custom OS. The values that were there before mean nothing.

  5. #5
    EFILive Distributor dfe1's Avatar
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    Don't mean to be rude, but you are missing something. Look over the standard open loop AFR table and the one from the custom OS. The GM table controls AFR based on MAP and coolant temp, the custom OS table controls AFR based on MAP and RPM. So how would you take values from the GM table and plug them into the custom OS table? That would be like taking a farenheit to celcius temperature conversion chart and trying to plug in kelvin temperatures.

    With the custom OS, the system will operate in partial closed loop at the rpm/MAP values that have 14.63:1 as the commanded AFR. If the commanded AFR is other than 14.63:1, the system will operate in open loop mode. The concept behind this is to allow automatic fuel trim when operating conditions are relatively stable-- highway cruise, light acceleration and possibly idle (if the cam isn't too radical). During aggressive acceleartion, when richer AFRs are required, the system would operate in open loop.

    With this system, closed loop is partial because long term fuel trim is disabled. The assumption is that the VE table has been sufficiently tuned so that during closed loop operation, only minor AFR corrections are required, and those can be handled by short term fuel trim.

    Also keep in mind that the custom OS is designed for a wide variety of engine configurations. It's set up so that it can be configured for engines with mild, radical and insane camshafts, as well as for naturally aspirated and boosted engines. Most of these engines require a sophisticated custom tune. The custom OS is the tool-- not the end product. Take your time, read all the information and you'll wind up with a great running engine. You can't find better tuning software.

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