after a long time with no time for stuff like that I took the time to bring on my attempts to get the oilpressure and oiltemperature into my MS3.
I think there were already various threads about that stuff - but mostly using resistive sensors and using a pullup inside the MS. Problem with that is - most of the sensors have a sensor curve and not a linear behaviour.
I did like to go the easy way and get "easy" 0-5V llinear signals into the MS.
So here is my solution:
... is indeed quite easy - (especially for you US guys) - I used the Auber 5 BAR (75 PSI) Gauge Pressure Sensor, 1/8NPT
5 BAR (75 PSI) Gauge Pressure Sensor, 1/8NPT [AUBER-P205g] - $63.00 : auberins.com, Temperature control solutions for home and industry
Connecting is easy
+5V from MS Vref
ground from MS
signal wire into one of the analog inputs
Now you have to tell the MS what input it gets and what the meaning of the 0-5V values is:
So - it's oil pressure, -0.6bar at 0V and 5.6bar at 5.0V - as to be seen here:
... is a bit more complicated
All the common sensors (NTC) use a sensore curve and are not linear - like this
As the Megasuirt only has very few 3-point sensor calibrations - this would lead to a big deviation on most of the temperature curve.
This lead me to the PT100 sensors - linear, highly correct temperature sensors. (in 2, 3 or 4-wire layout to delete the resistance error of the wires)
But - you need an evaluation board to get a "correct" signal out of this sensor for the megasquirt. (As I said 0-5V preferred in my case)
Well, I found a solution for this for reasonable money:
Again - lucky US boys:
Oil/Water Temperature Sensor, High Precision [PT100A-NPT] - $28.50 : auberins.com, Temperature control solutions for home and industry
This sensor is not easily available in Germany - so I did use this:
Temperaturfühler mit 2m Zuleitung ...105 Grad - Pohltechnik
And this is the evaluation borad DIY kit (sorry only in German, but I think you will find something like this in the US too)
Bausatz PT100 Messwandler - Bausätze / Module - Bausätze - - Pollin Electronic
Problem for me was the M6 thread of my German sensor - I had to make an adaptor with one of my sandwich plates 1/8 NPT blinds. Drilled, tapped and shortened a bit to hold the M6 sensor. (unfortunately there is no 1/8 NPT male to M65 female adapter available)
The evaluation board is a DIY kit - so some soldering required
The board needed a case - luckily I had an old mini-screwdriver case around with a perfect fit. Some self-adhesive velcro and it's mounted on the tunnel behind the center console.
Setting up the evaluation board needs some patience - I used a variable resistor to set the upper and lower measuring range and according output.
I got the 5V to feed the evaluation board from an automotive adaptor for mobile phones - but as the board only draws 30mA I think it could be fed through the +5Vref out of the Megasquirt too.
Now I made myself 2 new gauges in my TunerStudio dashboard
And this is it - now I can log and read the values in TS/MS.
In MS3 there is even a warning function with minimum oilpressure over rpm and a warning light output.
I thought this might be of some relevance for some of you on here...