31-2130-75 not reading correctly | AEM
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jcbryantllc
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31-2130-75 not reading correctly

Hi I hooked up a 31-2130-75 5 bar map sensor to my HPtuners to get an accurate reading of MAP on my 2015 mustang. I have 5v to senser power from an inovate motorsport SSI-4 to sensor power. signal ground and signal input are going to the prolink of HPtuners.

Ive gone through and selected the correct sensor in HPtuners software. The sensor is reading but it is reading low at all times. key on engine off it reads 1.20psi. shouldnt it read at least 14.7psi if my barometric pressure in my area is showing 29.91inhg?

maybe i have something wrong. 

any help would be appreciated thanks.

AEM_NS
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Can you see the live sensor

Can you see the live sensor voltage in HPTuners?  1.20 psia would correspond to about 0 volts.  If that's the case, there's a chance you got the 5v and sensor ground pins in the sensor connector mixed up.

jcbryantllc
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I double checked my

I double checked my connections to my sensor and hp tuners prolink

5v goes from ssi-4 to 5v power on top right pin of sensor

hptuners prolink black wire ground goes to signal ground top left pin of sensor

hptuners prolink red wire analog 1 (0-5v 100hz sampling rate)  goes to signal input bottom pin of sensor

I can not watch sensor voltage that I have found. i tried switching signal ground and signal input around. it reads 2 psi no matter what.

atleast when the engine is running with connections the way i explained above. the reading will change when the engine is running.

 

 

Chris Bryant

AEM_NS
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Probably time to get out a

Probably time to get out a multimeter and actually check to see what the voltage output from the sensor is. Really doesn't make any sense that you'd still have the same reading with the sensor wired two different ways. Sounds like a software configuration problem. So the reading will change with the engine running but from what to what?

AEM_HB
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Also, Its important to note

Also, Its important to note here that your weather channel based baro number might be reported as 14.7, however that is not the actual barometric pressure (which changes based on elevation)

jcbryantllc
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Thank you both for replying

Thank you both for replying and helping. I originaly had checked my local weather using AIRLAB app on my phone. today is shows my location at 30.18 inhg. which converts to 14.82psi.

I will check volltage to and from sensor this evening. Im suspecting its a issue on HPtuners. they have the 31-2130-75 labeled as a 4 bar and the function is

V/ 0.05333 + -24.075 = output psi.

to me this does not match what AEM has on the instruction sheet for 31-2130-75 5 bar pressure sensor PSIa which is   0.5v = -14.7psi.

Chris Bryant

AEM_NS
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That math is correct. All

That math is correct. All they're doing is taking the reciprocal of the slope (18.75) and dividing the voltage by it instead of multiplying like is usually done. So that part of it looks correct and the wiring you described also sounds correct. Voltage readings from a multimeter should tell you exactly what's going on.

jcbryantllc
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tested volatage on circuits

tested volatage on circuits while sensor is connected by probing wire. Sensor power shows 5v. Signal input shows 1.4v. Sensor ground showed 42mv.

I changed settings in the user defined area for sensor input.  Hptuners has their math set up for 31-2130-75 as (V/0.05333)+ -24.075= output

I did (V/1.35)+ 13.8 = output. my sensor now reads 30.15 inhg.

my local weather showed atmospheric pressure at 30.18inhg tonight.

I can suck and blow on the sensor and get it to show pressure change.

I started the engine and the sensor didnt show any change. Ill keep messing with it and reply back.

Chris Bryant

AEM_NS
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Did you hook it to the engine

Did you hook it to the engine somewhere that doesn't actually have manifold pressure on it? Doesn't make much sense that it'd work off the engine but then not work when on the engine.

jcbryantllc
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Thank you very much for the

Thank you very much for the help going through diag. sensor working great now that i went through user defined setting and set up my own math. HPTuners math is incorrect for this sensor.

this is the math i used to get the sensor to read accurate

input (1.35)+13.5= out put for hptuners

Chris Bryant

jcbryantllc
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I finally got some time to

I finally got some time to use the sensor after chasing other issues. Im not sure the math i figured was correct or somthing else has gone wrong. the sensor is reading very erratic. I've double checked my wring. I loud tested the circuits with the sensor and Hptuners pro link disconnected. all 3 circuits lit a 3157 bulb fine. Im going to contact tech support to see if they can help

Chris Bryant