i have spent a lot of time on calculating thermistor curves as i calibrated my dash mounted digital engine coolant/engine temp gauge.
the spec's on the panasonic thermistor that i put one each of on each side of the block has spec's that go from 40 degrees C to 125 Degrees C. so, the low side of the spec is about 100 degrees F. however they use a baseline calibration temperature of 25 degrees C for a resistance of 1000 ohms.
a thermistor is inside the temp senders and it is a resistor that varies in resistance with temperature. the resistance goes down with an increase in temperature. the relationship is very nonlinear. the resistance below 25 degrees C (75ish F) is very inaccurate on mine and i assume most of them.
here is a general scale for the thermistor for the senders i have put in.
Resistance Reading F
1000 ohm 74-78
100 175-179
50 215-219
30 248-252
so, in other words, i wouldnt use the temp senders as a gauge for actual temp. could be accurate i guess for lower outside temps, but certainly not on mine.
would be much easier to use a temp gun and shoot it...
btw, because the temp senders i got were off in calibration, i built a resistive network of variable adjustable resistors and have had darlene tuning them with a microscrewdriver as i drive. i have one zeroed in and the other one almost there. they are wayyyy not accurate at temps when the engine isnt running.
i have the acutal thermistor part number of the senders i put in if anyone wants it and or the temp curves and charts.
it ends up the way i calibrated (i have a single digital gauge on my center console and i use a rocker switch to move between temp senders on the left and right bank of the 8v92) is that i used the DDEC2 temp as the reference temp as i have compared it to everyone elses as i have driven with them and i believe it to be accurate. then i just at a steady temp, adjust the ones i have (try to do it at 180-185) to match it.
not very scientific, but the only thing i could figure to do.
the digital guage basically is an ohmeter that measures the resistance, then has a memory chip inside the gauge that has a lookup table of all the temps vs resistance and it looks up the resistance, and puts that temp number on the gauge. it has about a 10-15 sec delay so it isnt in actuality instantaneous.
i just quickly checked my digital gauge (not the vmspc) and with an outside air temp of 58 degrees, the gauge read 80 degrees.
so, in other words, i would guess that your vmspc is not showing the actual temperature. so i would also guess that actually you are not heating anything up. the starting right up thing i cant comment on. i could also be wrong, but can only guess based on my experience with these thermistors.
not sure you wanted all that, but you got it. take it for what you paid for it.
later
tom
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