Oil PSI / Coolant temp Ohm values (1 Viewer)

[ChaserFJ60]

I'm doing a little pet project and I need to be able to calculate the Coolant temp per Ohm and Oil Psi per Ohm of resistance and im having a hard time finding values for the stock FJ60 sending units.

I found the water temp sensor values to as such

WATER TEMP CELSIUS​	RESISTANCE OHMS​
50​	226 (+33.6/-36.6)​
115​	26.4 (+1.71/-2.21)​

I think I can find the approximate temperature values between 26.4Ohms and 226Ohms with this formula (Not including the margin of error...yet)
Y = -.0207155395 * X^2 + 4.902950848 * X
With Y=Temperature in C, and X=Resistance.
I think all I needed to do was calculate the slope? but I could be wrong.
I don't have a stock temp sender anymore so if somebody could verify that I'm in the ball park that would be very nice.

As for the oil pressure sending unit, I cant find any info online WRT PSI/Ohm's. Id rather just have some #'s and calculate this but I may have to just to an experiment if nobody has these values.

thanks in advance!

 

[rustybucket]

I'm doing a little pet project and I need to be able to calculate the Coolant temp per Ohm and Oil Psi per Ohm of resistance and im having a hard time finding values for the stock FJ60 sending units.

I found the water temp sensor values to as such

WATER TEMP CELSIUS​	RESISTANCE OHMS​
50​	226 (+33.6/-36.6)​
115​	26.4 (+1.71/-2.21)​

I think I can find the approximate temperature values between 26.4Ohms and 226Ohms with this formula (Not including the margin of error...yet)
Y = -.0207155395 * X^2 + 4.902950848 * X
With Y=Temperature in C, and X=Resistance.
I think all I needed to do was calculate the slope? but I could be wrong.
I don't have a stock temp sender anymore so if somebody could verify that I'm in the ball park that would be very nice.

As for the oil pressure sending unit, I cant find any info online WRT PSI/Ohm's. Id rather just have some #'s and calculate this but I may have to just to an experiment if nobody has these values.

thanks in advance!

Yeah I was saying if you just draw your own chart that will help

 

[OSS]

A while back I logged a brand new FJ60 temperature sender up to 212°F in water.
See attached file. I recorded it with a Redfish data logger.
Temperature vs Ohms is not a linear progression.

 

[ChaserFJ60]

A while back I logged a brand new FJ60 temperature sender up to 212°F in water.
See attached file. I recorded it with a Redfish data logger.
Temperature vs Ohms is not a linear progression.

View attachment 2591761

Thankyou for the PDF!
I dont quite understand that graph. The units dont match and based off your pdf starting from 310s going to 4565s neither the Ohms or temperature have a rise and fall or a fall and rise. Both units appear to act logarithmic

 

[OSS]

The graph above shoes temperature vs ohms over time starting at around 75°F as the sender was slowly heated to about 265°F and allowed to cool.

The graph could start at around 1100 seconds where the temperature is 265°F and the resistance is lowest, to present a more even looking graph, but I included the resistance readings starting at around 75°F to show what the sender resistance is at that (non relevant) cold temperature.
At any rate, the graph is just for visualization purposes which is why I used thick indistinct lines to mark data points.

Below is another (head scratching) graph to sort of illustrate what the sender resistance trend is doing vs temperature.

For example:
At 180°F, a 5° increase in temperature corresponds to a 7.4 ohm drop in sender resistance, but at 245°F, a 5° increase in temperature corresponds to only a 1.4 ohm drop in resistance.
This graph may not be the best way to illustrate that, but it sort of shows the relationship.