11-04-2007, 12:42 PM
Join Date: May 2005
Location: Chantilly, VA
Total Cats: 1,362
the bias resitors move the reference voltage around, iirc.
Esaytherm generates a table with your giving inputs so MS can correctly understand what the resistance value it sees means.
; Generated 05/07/2004 22:21:41 by MStoolsII
; GM #12146312
; Standard GM type Coolant Thermistor for Megasquirt
; Computed Steinhart-Hart coefficients: A=0.00162549 B=0.00019531 C=3.00954e-07
; 0 Fahrenheit = 25000 ohm
; 100 Fahrenheit = 1800 ohm
; 210 Fahrenheit = 185 ohm
; For use with 2490 ohm bias resistor installed at R7.
; ADC Fahrenheit - Celcius - resistance in ohms
DB 210T; 0 - sensor failure, use limp home value.
DB 255T; 1 408 209 10 ohms
DB 255T; 2 353 178 20 ohms
DB 255T; 3 323 162 30 ohms
notice the bias resistance statement? it's looking for a specific bias, when you're sharing that signal with the stock ECU the bais resistance is raised, becuase the stock ECU has it's own resistor. So the scale on which you generated your table will be off.
what will happen if you dont remove r7 and share the coolant sensor with the stock ECU is your temps will display 30*F cooler than they really are.