Adding VDO sensors to MS3 and sharing with gauge?
 

Hi to all the MS experts on here,

I have 3 additional VDO sensors on my Miata and would like to bring them into the MS (and maybe share them with the VDO gauge?!)

1 oil pressure sensor
1 oil temp sensor
1 coolant temp sensor (not needed in the MS of course)

Sensor is like that:
http://www.vdo-instruments.com/senso...-4-18nptf.html

The sensors are all resistive(?) sensors and don't give out 5V that the MS would need.

How would I have to wire the sensors to make them readable in th MS and would I be able to share them with the original VDO gauge...

I have seen that the new MS3 firmwares already have a oil pressure menu - how would I have to set this up... ?

Thank for your advices and sorry for my electronic noob-ness....

Greets
Sven

O.K. seems I need to put a bias resistor on the MS3X card R65 or R66 or R67 to use

Ext map
EGO2
Spare ADC

as additional inputs - in the schematics the resistors show a value of 2,49kohm (like the other temp sensors).

Now I do have a whole bunch of extra resistors lying here - but as it is no single 2,49k ohm one. Can I also use a 1k resistor?

Those sensors function just like your IAT sensor which is a variable resistor. MS has an internal voltage divider circuit to convert that resistance into a voltage. I do not know how many of these types of inputs your MS has. It might only have 1 for the IAT. If it does have more you would most likely just need to input the calibration curve values to have the data scaled appropriately.

If you only have 0-5V inputs available you can make you own circuit to do the signal conditioning. It's just 2 resistors really. I believe the sensor that have power, grnd and signal out have this type of circuit internal to the sensor.

AS220 Arduino Workshop

DANGER TO THE MANIFOLD!

So, yeah. These are resistive sensors, just like the stock temperature sensors.

And they require a pullup, just like the stock sensors.

The difference here is that the gauge you plan on also connecting to them already has it's own internal pullup (you can't have two pullups), and you don't know what value it's using.

For starters, it's probably using 12 volts, so you'll need to build an external voltage divider or else you'll blow up the ECU.

Beyond that, you just need to determine the pullup resistor value and then compute the resultant voltage curve. For this, you just need a voltmeter, a load resistor of known value, and math. I'd go into more detail, but I'm at a bar in the Indianapolis airport right now, and this whiskey ain't gunna drink itself.

I ditched the idea of sharing the sensors - so I guess the pullup to 5v will be fine.
Does a 1k pullup do the trick?

And how do I evaluate the ADC for Tuner Studio for the sensors? I do have the
Specific resistances for the sensors in a spreadsheet, but the inputs in TS are 2 value linear only anyway...

That's not for the '99 with the Basic MS3, is it?

Nope, for my 96 VVT swap MS3X...

The 99 with the MS3Basic is waiting for the ExtremeMS3... hint, hint.... ;-)

Booooo. The Basic MS3 already has 2.49K pullups.

You won't be able to use custom NTC-type thermistor sensors with the MS3. You need to use either a sensor that has the same curve as the CLT or IAT sensor, or use a linear sensor. These usually have a linear 0-300R output.

Ah, damn'it