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Hey what’s up guys. I have a 150psi stainless steel body Honeywell pressure sensor PX2AN2XX150AAAX. I installed it and calibrated it using .50 - 4.5 and linearized it. However the reading I’m getting is 10 psi higher than what my mechanical gauge reads. Does anyone have a calibration table for the sensor? I tried searching online for it but I must not be looking in the right places. Any help would be appreciated
What is your reference voltage? I believe that sensor my be ratiometric (meaning the output scales with the reference voltage), so if your reference voltage was say 5.4v, then it could read .4V higher which would be about 10 psi difference.
Here is the datasheet on that product -- looks like the "AA" configuration is ratiometric 4.75 - 5.25v, the low value is 10% of the reference voltage, and the high is 90% of the reference voltage.
Hey David thanks for you reply. I have a 5v supply to the sensor. So by scaling it to 5v I’m off by .5v and that’s causing it to be off by 10psi ? Should I rescale it to 5v.
I believe the issue may be that your 5V supply is not exactly 5V, but really 5.2V, 4.8V, etc --- can you measure it with a digital multi-meter you trust to get the actual voltage? Since this is oil pressure, you probably have the engine running. Can you put an oscilloscope on the 5V line to see if there is any noise when the engine is running?
What ECU / Logger are you using? Are you sure your mechanical gauge isn't off by 10 psi?
You need to confirm your reference voltage (what you're calling supply) is actually 5v. The sensor output is ratiometric of its input so whatever you're ACTUALLY feeding the sensor will affect what its output is.
edit: David responded while I was typing between bites of breakfast and is saying essentially the same thing as myself. Listen to him, he's the smarter of the two Davids in this thread.
Thank you both David’s for the responses. I have a haltech elite 550 on a rx7. I used one of the 5v sensor wires and one of the sensor grounds. As for the mechanical gauge being off. I haven’t thought about that one being that it’s relatively new but that could also be a problem. I’ll put a multimeter on the sensor supply and check for the actual voltage on the wire. Thank you guys
Cool, I've got 5 rotaries in my shop at the moment in various trim, from carb'd vintage IMSA racer to turbo 20b GT tube frame ride. Shoot me a DM if you're stuck on anything rotary related if you'd like.
Thank you David.I’m trying to get it running right. Fixing all the bugs little by little it’s a s5 streetpored motor no emissions no oil metering pump stock turbo for now . The hardest part of this whole project is the tuning. Being that it’s my first time tuning im trying to take baby steps I definitely appreciate your input and your willingness to help and share knowledge.
Hello, all after reading this thread I realized I'm running the same Honeywell pressure sensor PX2AN2XX150AAAX absolute. I'm trying to set up 2 of these sensors 1 for manifold pressure/vacuum and the other for fuel pressure on my Aem Infinity 508 and with regards to the ratiometric output and fuel pressure reading do I just check the 5 volt supply wire at the connector with my digital voltmeter and input that reading as the max voltage in the calibration for example 0.5v-5.12v. Also, by entering 0.5v will the ECU know that it supposed to be 0 psi. Lastly, for the Map sensor would I go through the same process as before but this time change the scale to account for vacuum reading, for example, 0.5v = -14.7Hg & 5v(or whatever the supply line is) would = 135.3 psi? any help on this would be greatly appreciated, I believe I should have purchased the gage style sensor instead of absolute but if these will work use them if not I'll just have to purchase the Aem units
oh i just did this calibration on mine. yes the sensor reads absolute so its really ~14.7 high compared to gauge pressure. im running a link g4 and could not reference a negative pressure number so you can put the slope in excel and figure out what voltage =14.7 (i forget the value .8xx or something) and use that as the zero point and then use 135.3 for the 4.5 v point.
ideally you'd just buy the gauge pressure unit but i made the same mistake
oh here it is .892 vdc equals 14.7 psi so that will be 0 psig
OK awesome so the 0.892v will be the new min voltage for the fuel pressure gauge so it will read as 0 psi then the 4.5 voltage will be the max 135.3 psi thank you soo much for the information this helps a ton. Now I'm wondering if I need to do anything to make the map sensor work because it is already an absolute sensor
not sure what MAP sensor you have but typically you read that as it comes in absolute pressure. in that case generally the ecu is using the value so it probably wont let you into negative values (the implication of absolute). you could possibly create a virtual value with a different calibration if you really want it as long as the ecu has provisions for that. same scaling trick
It's the same sensor honeywell px2an2xx150paaax so are you saying I should be able to just set it up as is 0.5v-4.5v min max respectively
yes as long as 0psia is .5v and 150 is 4.5v
you dont want to shift the map scale because it could alter the fuel calculation
Great replies team