testing pressure transducers

[RANDALL]

And then to complicate things, there's the "GAUGE" curve, or the "ATMOSPHERIC" curve. As in "PSIA or PSIG". The Gage curve takes into account atmospheric pressure, using a 15PSI offset. The other does not.

I'm hearing you now.

 

[bison]

Great point, and you are correct, SSI PN (P51-100-A-B-P-5V-000-000) measures absolute pressure. So if I take dash pressure (absolute) and -14.7 (gage) that gets me to dash = 50.3 psi (closer to 44psi mech gauge is reading.



Interesting, thanks for the reply.

--------------------------------------------

Any opinion on experience, which have you deferred to, mech gage or sensor as being most accurate? I would imagine gauge would be +/- 5% worst case. Need to figure out how gage vs absolute correlates to XFI gain/offset. Fast told me that their sensors are absolute as well, but, could not offer any advice on what to do with gain/offset tables to correct other that what turbo nasty and I have done. Surprising that Fast tech was unaware of similar issues (?) but was approving of turbo nasty and I did.

Anyone have similar issues/experience and find a different solution?

Those are the wrong sensors. Stay posted. May have a solution to that problem in the next week. FAST are not absolute tmk.


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[bison]

There you go. Right in the package


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[RANDALL]

Those are the wrong sensors. Stay posted. May have a solution to that problem in the next week. FAST are not absolute tmk.


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That would be great and thanks for your help. Just FYI... Fast tech told me their sensors were absolute (maybe incorrectly, he didn't do a look up).

 

[pacecarta]

also that sensor is a 12v input

 

[bison]

FWIW on my XFI 2ish volts...Thats around where mine is at to read where the analog for both fuel and oil psi logging

Chances are you have the wrong transuducers also. Stay posted for a possible solution in then next week. The oil and fuel through the egr is hard coded at 0 and 100psig. No way to change it and you can't get the voltage range to work with that. The value at 5v would need to be 85.3psig if using an an absolute sensor and since there's no way to change the max value you can't get it linear. Leaving it at 5v max and 1v min it will be off linearly on atmosphere.


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[turbo nasty]

Ill need to look at my laptop and see. Its in the sensor calibration not the offset and all that bizzness.

 

[bison]

Ill need to look at my laptop and see. Its in the sensor calibration not the offset and all that bizzness.

You can't offset with the oil and fuel pressure through the egr. That's the problem. Unless you have 0-100psig transducers. There's no way to currently update the calibration for absolute sensors. Look at the stickers on your transducers for verification


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[turbo nasty]

So i checked and its .2 not 2 in the fuel psi cal menu. These are 0-100 psi transducers off of ebay. So far so good with them.

 

[RANDALL]

All,
Thanks for the replies/help.

GNVenom, Bison,
You were correct, wrong sensors. Need PSIG not PSIA sensors for XFI. With correct sensors used FAST settings for offset and gain and both fuel and oil pressures are reading good compared to mechanical gauges. Raw V is now a good correlation to PSI.

Pacecarta,
Thanks for helping me get to the right place in C-Com to get sensors set up.

FYI... table below for linear PSI/V using a 12V in, 1 - 5V out, 0 - 100 psig sensor.

PRESSURE - VOLTAGE - INCREMENTAL INCREASE
0 - 1.00 - 0.04
2 - 1.08
4 - 1.16
6 - 1.24
8 - 1.32
10 - 1.40
12 - 1.48
14 - 1.56
16 - 1.64
18 - 1.72
20 - 1.80
22 - 1.88
24 - 1.96
26 - 2.04
28 - 2.12
30 - 2.20
32 - 2.28
34 - 2.36
36 - 2.44
38 - 2.52
40 - 2.60
42 - 2.68
44 - 2.76
46 - 2.84
48 - 2.92
50 - 3.00
52 - 3.08
54 - 3.16
56 - 3.24
58 - 3.32
60 - 3.40
62 - 3.48
64 - 3.56
66 - 3.64
68 - 3.72
70 - 3.80
72 - 3.88
74 - 3.96
76 - 4.04
78 - 4.12
80 - 4.20
82 - 4.28
84 - 4.36
86 - 4.44
88 - 4.52
90 - 4.60
92 - 4.68
94 - 4.76
96 - 4.84
98 - 4.92
100 - 5.00

 

[pacecarta]

i think you mean 1-5v out sensor

 

[RANDALL]

i think you mean 1-5v out sensor

Yep, good catch. I'll edit.