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Topic: Reading Temp Sensor from Car Engine (Read 2 times) previous topic - next topic

vampyre

Hi folks, i hope i;m repeating something that was already asked,

I.m new to the arduino scene... been looking to make a digital Coolant Temp Gauge and a Oil Pressure Gauge for me project Car VW Golf Mk2, to an LCD display, i was wondering would it be possible to read in the values from the standard engine sensors coolant temp and oil pressure , if so how would i go about doing it ? any advice would help I got the LCD wired up and working just need to work out how to interface with the senrors of other alternatives

thanks in advance

mrmeval

What you want is ODBII

http://en.wikipedia.org/wiki/On-board_diagnostics

http://en.wikipedia.org/wiki/OBDuino

The OBDuino can read that and more.
If it was designed by man it can be repaired by man.

MLuckham

You could also use the MPGuino platform http://ecomodder.com/wiki/index.php/MPGuino, and do some reprogramming to display oil pressure and temperature instead of fuel economy.

Reboticon

Good luck converting a non obd2 car to obd2. Evap will give you nightmares. Your car will have 2 temperature sensors. One used by the ECU, called the ECT (electronic coolant temp) or TW (temp,water) depending on manufacturer, and it will also have a 1 wire gauge sensor. The 1 wire gauge sensor is just a standard thermistor. It would be hard (at least for me with only basic arduino knowledge) to incorporate the gauge sending unit thermistor, because its essentially a simple circuit and the only thing changing is resistance.

Here is what I would do.
Measure voltage at ECT as soon as car is turned on, compare to ambient temp. Then look up the thermostat specs on your car ( Its probably 180 but could be 170 or 190). This is the degree is temperature that your temp gauge quits rising because the thermostat opens. Measure voltage here.  If you have a pyrometer ( infrared thermometer) make a few more points along the curve in case the voltage isn't linear. Then connect to analog pin with the formula you devise.

vampyre

Thanks for all the replys,

the car has no OBDII, its running an after market EFI , i dont mind adding extra sensors, i at the momemnt i have mechanical gauges for the coolant temp and the oil pressure the Vdo type.. so i dont mind adding extra sensors to the plumbing of the car. any options on what type of sensors i could use that would integrate with arduino with easy ?

Funky Diver

I have them, somewhere... I'll dig them out, and you don't need to use extra sensors, just usse the ones you already have.

From memory the voltage range is between 0-5 volts, but let me grab the link for you... might take a while though as I think it might be on my work PC.

I have a Scirocco, so basically the same wiring loom.  Out of interest are you running injected or carbs?   ;)

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