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Old 01-28-2016, 04:30 PM   #22
ztan
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Join Date: Jul 2013
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Rev limit code

Shiv asked me to look at an RPM limit problem under boost and there is something interesting in the code worth noting:

Rev Limit A and B have their cut and resume values in different directions (see disassembly pic). No reason for the engineers to do this and Rev Limit B works without hysteresis in the stock ROM which is has 7400 as the first (resume) value and 7200 as the second (cut).

A01G def:
Code:
    <table name="Rev Limit A" storageaddress="10C524" />
    <table name="Rev Limit B" storageaddress="10C52C" />

    <table type="2D" name="Rev Limit A" category="Miscellaneous - Limits" storagetype="float" endian="little" sizey="2" userlevel="1">
      <scaling units="Engine Speed (RPM)" expression="x" to_byte="x" format="#" fineincrement="50" coarseincrement="100" />
      <table type="Static Y Axis" name="Rev Limit Fuel Cut" sizey="2">
        <data>On Above</data>
        <data>Off Below</data>
      </table>
      <description>These are the engine speeds at which the rev limiter is engaged and disengaged. When engine speed is equal to or exceeds the 'On' value, fuel cut is active, after which, if engine speed drops below the 'Off' value, fueling is resumed.</description>
    </table>
    <table type="2D" name="Rev Limit B" category="Miscellaneous - Limits" storagetype="float" endian="little" sizey="2" userlevel="1">
      <scaling units="Engine Speed (RPM)" expression="x" to_byte="x" format="#" fineincrement="50" coarseincrement="100" />
      <table type="Static Y Axis" name="Rev Limit Fuel Cut" sizey="2">
        <data>Off Below</data>
        <data>On Above</data>
      </table>
      <description>These are the engine speeds at which the rev limiter is engaged and disengaged. When engine speed is equal to or exceeds the 'On' value, fuel cut is active, after which, if engine speed drops below the 'Off' value, fueling is resumed.</description>
    </table>
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