Originally Posted By: LAGA
Originally Posted By: clinebarger
What is your definition of a "Boost Gauge".....One that reads zero at sea level with the engine off?
There should be a MAP PID readout from the OBD.....It just reads "Absolute Pressure", Not "Relative Pressure".
a boost gauge reads the pressure a supercharger puts out. At idle or partial throttle it will read as a vacuum of around minus 30 pounds as this is the measurement of air being sucked in by the pistons. Under heavy acceleration, my gauge will go up 6 pounds. This is the measurement of air being pumped into the engine by the supercharger. Cars built without S.C. do not have this sensor, so you have to add one yourself. Mine is a aftermarket SC made by Edelbrock.
Yes sir, I understand how it works. I think you misunderstand "Absolute" vs "Relative".......Only "Boy Racer" & Diagnostic gauges read relative pressure (My Cobalt has a factory installed "Boy Racer" Vacuum/Boost gauge) So don't take this as me bad mouthing you or your car. I also have a Aeroforce Interceptor in my Camaro.
Relative Vacuum/Boost gauges are set to 0-PSI at sea level which is actually 14.7-PSI Absolute Pressure.
When reading a OBD date stream or logging OBD data......The reading will always be Absolute (PSI or KPA) There is different scaling depending on what MAP sensor your using (1-BAR/2-BAR/3-Bar).
I don't know what year/engine Mustang you have, But I do recall some Fords not having a MAP & relying only on MAF/BARO input for base fueling/VE which I am not crazy about....But that's another topic altogether.
If I were you.....
*Buy a GM 2-BAR MAP Sensor part# 16040609 (Can read over twice the boost your making)
*Your ECM has a VERY stable 5-Volt reference circuit (C-Circuit in Ford speak) The A/C pressure transducer is a good source to piggyback off of....No reason to buy a signal converter/conditioner!!
*Scale the Aeroforce gauge to read the MAP output to your liking.
GM MAP sensor wiring....
Pin A -- Ground, To a GOOD ground (Engine Block/Battery)
Pin B -- Sensor output, To the Analog Input on your Interceptor gauge.
Pin C -- +5 volts, A/C pressure transducer C-Circuit.
GM 2-BAR sensor scaling.....
Relative / Absolute-----------------MAP Output VDC
14.31psi / 29.01psi-----------------4.90V
14.00psi / 28.70psi-----------------4.84V
13.00psi / 27.70psi-----------------4.67V
12.00psi / 26.70psi-----------------4.50V
11.00psi / 25.70psi-----------------4.33V
10.00psi / 24.70psi-----------------4.16V
9.00psi / 23.70psi------------------3.99V
8.00psi / 22.70psi------------------3.82V
6.00psi / 20.70psi------------------3.47V
4.00psi / 18.70psi------------------3.13V
2.00psi / 16.70psi------------------2.79V
0.00psi / 14.70psi------------------2.45V
5.00inHg / 12.24psi-----------------2.03V
10.00inHg/ 9.78psi------------------1.61V
15.00inHg/ 7.33psi------------------1.19V
20.00inHg/ 4.87psi------------------0.77V
25.00inHg/ 2.41psi------------------0.35V
29.10inHg/ 0.40psi------------------0.02V