Adding a resistive sensor
Moderators: jsmcortina, muythaibxr
Adding a resistive sensor
So I am attempting to add a resistive coolant temp sensor from a saturn for my oil temp. I had found it online, on msextra I think, where people recommended using it. However, my understanding was I just put 1 lead to ground and 1 lead to an analog input (EGO2) on the ms3x card. Set to GM calibration. Did not work, and the values are crazy, and jumped a lot. Do I need to a 12V pullup with a 1k resistor to make this work? Or is there something else I am doing wrong?
-
- Super MS/Extra'er
- Posts: 1341
- Joined: Mon Sep 05, 2011 1:20 pm
Re: Adding a resistive sensor
Ground is sensor ground, correct? Back to the MS unit?
Graduate of EFI University.
I build, repair, install and tune Megasquirt systems in North Dakota and beyond!
I build, repair, install and tune Megasquirt systems in North Dakota and beyond!
-
- Super MS/Extra'er
- Posts: 1986
- Joined: Sat Jul 22, 2006 8:02 pm
- Location: Eureka, NV USA
- Contact:
Re: Adding a resistive sensor
I don't know anything about MS3, but I suspect that your ground should go to sensor return, as with all other MS sensor grounds!Schuyler wrote:just put 1 lead to ground and 1 lead to an analog input (EGO2) on the ms3x card.
I could be wrong, but I don't think so.
Ken
Last edited by kjones6039 on Sun May 24, 2015 8:42 am, edited 1 time in total.
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/extra 3.4.2 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
TinyIOX from JBPerformance
MS2 v3 w/extra 3.4.2 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
TinyIOX from JBPerformance
Re: Adding a resistive sensor
did you fit a resistor to the ms3x card??
R65,R66,R67 are optional 'bias' resistors on the analogue inputs EXT_MAP, EGO2, SPARE_ADC respectively.
These would be typically used when connecting a resistive temperature sensor to one of the inputs. For
standard calibration, use a 2.49K resistor with a GM style coolant or air temperature sensor.
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
-
- Super MS/Extra'er
- Posts: 6828
- Joined: Sun May 15, 2011 11:41 am
- Location: Walnut Creek, Calif. USA
Re: Adding a resistive sensor
You are going to need a 2490 ohm pull-up to the 5V ref; you need to build an input circuit similar to that existing for the (standard GM) CLT and MAT sensors. Look at the V3.0 mainboard schematics.
Ah, I see I was too slow in typing! Besides, the rely above is more thorough.
Ah, I see I was too slow in typing! Besides, the rely above is more thorough.
Re: Adding a resistive sensor
Thanks! I will add the resistor to the board. I did not use the sensor ground... Maybe I should consider moving the ground.