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%META:TOPICINFO{author="bigwig" date="1116647400" format="1.0" version="1.1"}%
Assuming that the stock map sensor's maximum reading is 1764 Mbar, the formula to convert MAP byte value is ((1764 / 255) * [[OBD1]] _8bitMBar / 2).  When the rom's map value has been [[uncorked]], simply remove the last division which results in the formula ((1764 / 255) * [[OBD1]] _8bitMbar).
 
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OBD1 Honda Map Sensor Information 
  
 
  
  
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       Stock Map:5/255*((Raw/2)+Fuel Cut) 
      Boost Map: volts=(5/255)*(Raw+fuelcut) 
      **Fuel cut stock is 24 and editable at 0x4dcc**  | 
   
 
  
    | 
       
2.85 V=0 
      "1.0V=20" 
      (20-0)/(2.85-1)=m 
      (y-0)=20/1.85(x-2.85) 
      inHG=20(volts)/1.85-30.81  | 
    
       
2.85V=1013mbar 
      "1.0 V=336mbar" 
      (1013-336)/(2.85-1)=m 
      (y-1013)=365.9(x-2.85) 
      mbar=365.9(volts)-29.9  | 
   
 
 
 
  
    | 
       Raw  | 
    
       0  | 
    
       24  | 
    
       48  | 
    
       80  | 
    
       128  | 
    
       176  | 
    
       208  | 
    
       224  | 
    
       240  | 
    
       256  | 
   
  
    | 
       Volt  | 
    
       0.471  | 
    
       0.706  | 
    
       0.941  | 
    
       1.255  | 
    
       1.725  | 
    
       2.196  | 
    
       2.51  | 
    
       2.667  | 
    
       2.824  | 
    
       2.98  | 
   
  
    | 
       mbar  | 
    
       142.3  | 
    
       228.4  | 
    
       314.5  | 
    
       429.3  | 
    
       601.5  | 
    
       773.6  | 
    
       888.4  | 
    
       945.8  | 
    
       1003  | 
    
       1061  | 
   
 
  
  
    | 
       Raw  | 
    
       0  | 
    
       12  | 
    
       24  | 
    
       40  | 
    
       64  | 
    
       88  | 
    
       104  | 
    
       112  | 
    
       120  | 
    
       128  | 
   
  
    | 
       Volt  | 
    
       0.471  | 
    
       0.706  | 
    
       0.941  | 
    
       1.255  | 
    
       1.725  | 
    
       2.196  | 
    
       2.51  | 
    
       2.667  | 
    
       2.824  | 
    
       2.98  | 
   
  
    | 
       mbar  | 
    
       142.3  | 
    
       228.4  | 
    
       314.5  | 
    
       429.3  | 
    
       601.5  | 
    
       773.6  | 
    
       888.4  | 
    
       945.8  | 
    
       1003  | 
    
       1061  | 
   
 
Raw values shown above are for a P72/75.  Most if not all OBD1 ECU's follow this rule though so its just a matter of plugging in different raw values.  Feel free to edit anything that is deemed incorrect.
-- bigwig - 21 May 2005
%META:FILEATTACHMENT{name="mapsensor.jpg" attr="" comment="" date="1116647201" path="C:\My Documents\mapsensor.jpg" size="10674" user="bigwig" version="1.1"}% |  
 
 
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