Analog input / CALC-PID

[AWL INN]

Hey all, I'm looking for a pressure transducer so I can log fuel pressure using the analog 1-5 volt input on the black box. Has anyone here used the analog input with a pressure sensor? I have been stumbling through the calc._PID to change the 1-5 volt single to a PSI but still having problems with understanding how to edit the calc.text script. Any help would be great!!! Thank you for any input!! Brett~

[mr.prick]

http://download2.efilive.com/Tutorials/PDF/LS1%20Fuel%20Pressure%20Sending%20Unit%20Tutorial. pdf
like this?

[AWL INN]

YES! thankyou! I fixed the PID from this tutorial and there it said they were using Autometer's 2246 pressure sending unit. Thanx again! Brett~

[AWL INN]

I found an error in the Tutorial in their math on the calc_pids.text in my setup anyway. The math they had setup was ({EXT.AD1}*25)-12.5 If the sensor is 1-5 volt and 1=0 and 5=100 this wont work right. 1x25=25-12.5=12.5 so 1volt would = 12.5 psi. and 5volts would +112.5 psi

Ok this is what I came up with an it works right for me.
PSI 0 100 .2 {EXT.AD1}*100/4-25

1v x100 = 100 /4 =25 - 25 =0psi
5v x 100= 500 /4 =125 -25 = 100psi

It seems to work perfect so I'm not sure what I did different that the Tutorial wouldn't work right. Just food for thought I hope this helps someone else on setting up the analog input. Brett~

[acsf]

Brett

Thanks for letting us know.
I came up with this after you pointed out the error "({EXT.AD1}*20)"

Thanks
Andy

[AWL INN]

Brett

Thanks for letting us know.
I came up with this after you pointed out the error "({EXT.AD1}*20)"

Thanks
Andy


Andy,

I still think that if you use ext.ad1 x 20 will not be accurate.
The sending unit will out put a range of 1-5 volts (if the out put is zero then something has failed) so 1volt would be 0 psi and 5 volts would be 100 psi at least on the sending unit I have (autometer) In your calc 1 volt would equal 20 psi when the pressure is accually 0. 5volts would be 100psi though.

The way around this is to take out the 1v offset and use a 4 volt range instead of a 5 volt range. For some reason EFILive didn't like the first calc I tried witch on paper works correcty. {EXT.AD1} -1/4x100 Im not sure why but wording it this way worked. {EXT.AD1} x100/4-25 It tracks my analog guage within a pound +/-. I hope this makes sense. Brett~

[Ninety8C5]

I think your first calculation didn't work because you are missing a set of brackets.

Try: ({EXT.AD1} - 1) * 25

[TAQuickness]

Welcome to the forum Brett. Sounds like you're off to a great start.
What sending unit are you using?

When Beer99c5 and I were working on this, we both spoke with Autometer and they stated the 2246 had a 0-5vdc output range. Just want to make sure the tutorial is correct.

[AWL INN]

Yeah, I was wrong. It is working from 0-5 volts. Now it's correct. I must have been smoken crack:) Thank you guys for the help. On a brighter note. I entered a Dyno contest last weekend. I made 594.2 RWHP with my EFILive tuned Duramax. Tune made by me and help from you guys. :) Brett~