Factory sensor voltage to value charts?

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Map63Vette

Map63Vette

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As the title suggests, does anyone have charts for the sensor ranges and matching output voltages for things like the MAP and oil pressure sensors? I can't believe it's this hard to find that info, but I'm not having much luck so far. I was hoping I could pull it off of a datasheet from someone like NTK or AC Delco or whoever makes ones that fit, but they only seem to mention vehicles that they fit on their websites if I can even find the sensors to begin with. Looking for values like 0V - X psi, 5V - Y psi kind of numbers. I'm going back through my setup on my Megasquirt and wanting to get them as correct as I can just for the sake of argument. They are mostly just there for extra info right now as they aren't critical to the car running, but I'd like them to be accurate if I'm going to have them. I tried watching the raw readouts while applying vacuum and pressure to the sensors, but the MAP sensor especially never made any sense to me the values I was getting. The oil pressure sensor I think I might have close with 0.5-4.5V readings of 0 psi and ~110 psi respectively, though I think the 4.5V reading seems a bit off. I'm thinking it should probably be 100 psi for 4.5V. Most 5V sensors values are given at 0.5V and 4.5V respectively, and most pressure sensors I've seen coming in 50 psi ranges, so I would expect it to have been 100 or 150 psi, maybe 120 as a bit of an oddball, but I haven't even found a maximum rating for the sensor anywhere. The MAP sensor should be pretty straightforward as well and I would assume would be similar with something like 0.5V being 0 psia and 4.5V being something like 14.7 psia (or 1 bar or 101.3 kpa or whatever unit you want), but it doesn't seem to agree with the MAP sensor built into my Megasquirt when I set it up that way, which is what got me going on trying to find the real specs to start with.
 
Some sensors very milliamps vs voltage or resistance.

Some output a small voltage ( thermocouple)
 
The old (60s, 70s) Mopar senders are about 10-70 ohms. 10 at full scale, 70 at zero. This is for oil gas, temperature.
 
Old school Mopar senders are close to the same. That is, temp, fuel, oil if equipped, are same basic range. They are resistance, not voltage.

Here is a tester photo somebody posted that shows low, med, high scale resistances

THEY ARE NOT a linear curve

c-3826-jpg.jpg
 
So far as Megasquirt, I bet that kind of think is buried in their website or forum posts, somewhere
 
BTW.

You can determine all the outputs with some testing

Pressure senders, rig up a t with a pressure gauge and pump some air in. Measure at 0 psi, 5psi,10psi etc.

Temp gauge get a pot of ice water on the stove, measure the output and the water temp as you heat it to a boil.
 
I guess I should have specified the actual 5.7 Hemi sensors for a 2006 vintage engine, not necessarily the old school ones, though maybe they aren't all that different. I tried the tee thing with what I have, but I don't necessarily have a good resolution gauge to use as a reference for what the values really are. I hooked my air compressor up for the oil pressure and used the regulator on the compressor to try to set a fixed pressure, but it's a harbor freight compressor with a gauge that reads in 10 psi increments, so hard to say how accurate it might actually be. For the MAP sensor I used a mityvac style hand pump with a generic gauge I got many years back for carb work, but working between vacuum and absolute pressure with unit changes in-between kept messing things up.
 
The short cop out answer is the factory service manual. Problem is the book or online ones for newer vehicle s aren't readily available. You can try going to the sensor suppliers webpages and look for technical resources. Some vendors have tutorials or books that have this information. I remember seeing a few but am having trouble finding any at the moment. I also seem to recall that Cardone had a paper book available at one time for pre Y2K vehicles.
 
The service manual crossed my mind as well, though I tried checking in the manual for my Viper and actually didn't find that much there (they use similar enough sensors at least, so figured it might give me a starting point). I did find a little info in there for the MAP sensor at least, though the range seemed a bit off. What I have now seems to track against the sensor on the Megasquirt quite well, just offset by a few kPa. I can just guess and check it to make them match I suppose, but figured it might be nice to have the "real numbers" just for the sake of argument. The oil pressure sensor is really the one I care more about since I can use it as a safety device to shut things down if I lose pressure. The MAP sensor is more a novelty since it's basically a duplicate value right now. I could actually unplug it from the manifold and use it as an ambient pressure sensor to account for current atmospheric conditions though, which is where it would be good if it reads right.
 
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