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Need help with formula for PSI

Posted: Sat Sep 14, 2019 4:31 am
by AMOD177
Hi everyone. New user here. I am running a Bosch 3 bar TMAP sensor on my intake plenum (before the throttle body). Currently it shows me pressure including atmospheric pressure. At my elevation atmosphere is about 11.7psi and 19.7psi under full boost. Is it possible to write a formula that uses an initial reading as a base line and subtracts that value from the current reading to give me how much boost the engine is seeing? I could always just subtract 11.7 from the formula but we do run at different elevations throughout the year. The goal is to see 8psi instead of 19.7. The sensor calibration is .400V=20kpa, 4.650V=300kpa which gave me a formula of (65.9 * x - 6.35)/6.895. The car does have a pressure sensor in open air that I could tap into if needed but i dont know its calibration. If it is too hard to do just let me know and will deal with having to do math in my head :D

Re: Need help with formula for PSI

Posted: Wed Sep 18, 2019 3:23 pm
by Stan
I'd be inclined to just add another sensor / channel. You could even use another 3bar Bosch sensor since you know the calibration for it. Or calibrate your other sensor by logging it and the Bosch simultaneously (replumbed) and then going from there. Then, a math channel to take the difference.