####   
     ##  
  #####  
 ##  ##  
  #####  
         

         
         
 ######  
    ##   
   ##    
  ##     
 ######  
         

         
     ##  
     ##  
  #####  
 ##  ##  
 ##  ##  
  #####  
         

         
         
 ######  
    ##   
   ##    
  ##     
 ######  
         

      _ 
     | |
  _  | |
 | |_| |
  \___/ 
        

IMPORTANT: enter the case-INsensitive alphabetic (no numbers) code AND WRITE SOME SHORT summary of changes (below) if you are saving changes. (not required for previewing changes). Wiki-spamming is not tolerated, will be removed, so it does NOT even show up in history. Spammers go away now.


Visit Preferences to set your user name
Summary of change:
Subpage of MembersPage/WolfTm When ECU is purchased with 1,2 or more (4 or 6 is sometimes requested, some logger was ordered and delivered with 8 EGT inputs), * '''EGT amplifier outputs''' are '''connected to inputs with no pullup''' Confirmed: * it was the internal ecu pull up ** 51K (really ? Usually 2k7 pullup on analog inputs) ---- '''Unfortunately NO input with no pullup resistor in this ECU'''. * is there a way to scale it mathematically based on the pull up? ** yes, since the function is monotone, it is possible to calculate. The EGT amplifier 5V output has a protection equivalent to * 1 / (1/75+1/100) = 42.86 k Ohm resistor ** 2.7 / ( 2.7+42.86) = 0.0593 ... this means 2k7 pullup causes a strong bias, and resolution is reduced * say 20C => 1102 C (at 0.02V measured on the 0-11V output ) * say 1170C => 1170C (at 5V) ** The theoretical formula for that case is: ** EGTconv1=1170 - (1170-20)/(1170 - 1102) * (1170 - EGT) ** EGTconv1=1170 - (1170-20)/(1170 - 1102) * (1170 - '''1147''') = 781 C for example ** Note: this is rough estimate, not based on actual measurement or calibration. ** even if calibrated, the scaling would be rather rough. Best to use input with no pullup. * input with 2k7 pullup will likely make the EGT reading granularity annoyingly rough * reasonable formula (VT ini can be tweaked to output real calibrated result) becomes possible if '''Connecting the analog input (with internal 2k7 pullup)''' via/to: ** '''6k3 to the 0-11V output of the EGT amplifier''' ** '''4k7''' "pulldown" to GND ** this way it acts like output divider with effective of 2k7=1/(1/6.3 +1/4.7) which means that half of the range is available, which allows precise measurement after simple calibration. ** Something like '''2*EGT-1170''' conversion will be sufficient and good granularity: ** 0C => 585C (2.5V on input) => 0C ** 1170C => 1170C (5V) => 1170C ---- '''Orig report:''' Engine off, ambient sensor temp (~20C) * Tested Pin7 DVM output (1V/100°C) and getting 0.7 volts ** corresponding to 70C ** not 6 volts, roughly corresponding to Pin6 2.5 volts. * '''I'm getting 2.5 volts out of Pin6''' (0-5V output, 1V/233.3C) ** '''Thus getting 580°C instead of 20°C.''' Hint: The '''output is almost certainly connected to an input with pullup''' (possibly strong pullup). * '''Diagnostic: disconnect anything from output, and measure DC voltage with DVM''' (the DVM has 1 to 10MOhm input impedance). * '''Solution: make sure to connect pin6 output to an input without pullup resistor''' '''Sensor connection (seems good)''': EGT sensor is K type yellow-red wires: ** yellow = green (plus wire) to board GND ** red = white (minus wire) to the board cathode on corner
Optional: Add document to category:
Wiki formatting: * is Bullet list ** Bullet list subentry ... '''Bold''', ---- is horizontal ruler, <code> preformatted text... </code> See wiki editing HELP for tables and other formatting tips and tricks.