([PID.2811]/.04)+.5
should be the formula. To increase the offset, you will adjust the .5 volts accordingly. I have been doing many things to my car and still have yet to activate my sensor and begin logging it. Hopefully soon though.
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([PID.2811]/.04)+.5
should be the formula. To increase the offset, you will adjust the .5 volts accordingly. I have been doing many things to my car and still have yet to activate my sensor and begin logging it. Hopefully soon though.
(volts/.04)+-12.5
"should be the formula"
0v= -12.5
.5v is 0psi
4.5v is 100psi
(0/.04)+.5=.5
incorrect.
(4.5/.04)+.5=113
also incorrect.
25 is the slope & -12.5 is the intercept.
(V*S)+I
Makes sense. That way .5v=0. I didn't actually run my formula or I would have known is wasn't right.
I am wondering if the formula ([PID.2811]+-.5)/.04 would work as well.
Since I have a Corvette, the EGR is turned off. I haven't gotten the output to show up in my logs yet, but I also haven't done much troubleshooting. I did go in the General tab and set the EGR to "enable" and set some (if not all) of the EGR items in the DTC's page to report and I have yet to see an output. I get the "unsupported" comment once I start the scan. I'll keep digging.
This is the formula: (V/.04)+(-12.5).
If you have an offset, calibrate the external inputs or compensate for it in the pid but
don't substitute the Intercept (-12.5) for another number.
You can use AA battery (1.5v) to see if you have an offset.
Is the sensor properly powered/grounded?
Here is a spreadsheet for WBO2 expressions but it will work for other devices as well.
Sorry for not responding sooner. I have been caught up with other issues. I am a solder and heatshrink guy, so it is properly powered and grounded. Thanks for that spreadsheet. I finally got it to work with the formula provided and verified it with an analog gauge. Since I have an adjustable regulator, I was able to turn the pressure up and down while monitoring the readings and it was close enough for government work. I then got a virus (damned 2010 internet security virus) and after I cleaned it out of my laptop my config files were screwed up. I also have been doing a bunch of other work to the car. I'll have to make my config files again soon. Still have other fish to fry right now. :doh:
Just curious why I would use a AA battery to verify offset. Because it's lower than 5 volts, stable voltage output and I can put a known good meter on it for comparison?
Final follow up on this.
For any formula on a linear pressure sensor, take the total pressure range and divide it by the volt range.
100/4=25
Since you can't multiply the sensor output (also the EIO or PCM input) signal by a factor, you divide it by it's inverse. 1/25=.04
Take your ([PID]/.04) + (- your intercept).
Since the sensor starts at .5 volts, then the intercept will be .5 * 1 volt value. .5*25 is 12.5 subracted from 0, so the intercept will be -12.5
([PID.2811]/.04)-12.5 is what I used for the EGR and I had to put EGR position voltage in your table to be able to log it. It works great!
Just an FYI, if you were to use a 150psi sensor with a .5-4.5v range it would change to ([PID.2811]/.0267)-18.75
Feel free to substitute with the pid of your choice.