is there a pid that i can use to log nitrous pressure if i have a dynotune nitrous pressure sending unit on the bottle? for some reason my custom pids won't save. the dynotune sender increases by .005 volt increments per 100 psi. is it not saving because hpt can't data log .005 volt increases?

 

I am interested in doing the same, what did Dean say was the wire (white?) and what is the voltage range for the unit? 0V=0 and 5V=1000psi?

 

5mV per 100PSI and 1200PSI is what, 60mV? That is a pretty
small quantity and though I don't know the resolution of the
A/D converters in the interface, I suspect it is not many bits'
worth (12 bits and 4V full scale, is 1mV per bit). Further the
small signal is liable to be easily corrupted.

If it were me (and I do think about this stuff) I would add an
instrumentation amplifier stage to the sender, gain it up to
the point that max bottle pressure produces something just
less than 4V at its output and then you will have better
resolution and some ground offset rejection as well.

Are you sure about the range / resolution and can you log
straight voltage (forgetting about translating it to cute
scale etc.) as a starting point?

 

Beer99C5- brown is positive, blue is negative, black and white are sender output.

Jimmy, in hpt, when i try to make a user defined pid in the LIST form with a volt of say 2.5XX, 2.6XX, 2.7XX, the pid won't save due to the XX digits. it will save if i only go into tenths,ie 2.5, 2.6, 2.7. but the nitrous sender's increments are .005 volts not tenths.

i don't have a clue how to use the LINEAR form. not sure what numbers to plug in or if it will work.
here is the volt range

PSI Volt
0 2.547
100 2.552
200 2.557
300 2.562
400 2.567
500 2.572
600 2.577
700 2.582
800 2.587
900 2.592
1000 2.597
1100 2.602
1200 2.607
1300 2.612
1400 2.617
1500 2.622

 

Can you log the voltage straight up? And then worry about
how to code the custom PID?

I think there's some funny business about how you have to
save the config, then quit and restart, for the new custom
PIDs to show up working. Don't pay much attention to that
myself but have seen some discussion of it on the HPTuners
'board.

If you can log the straight voltage, do it with the bottle at
a fixed pressure and see how much jumping around you get
from system electrical noise. That will tell you whether you
want to add some signal conditioning (like 2.5V reference,
gain and filtering) to get better fidelity at the logging input.

 

with bottle closed, i measured input at 2.32 volts cosistent with my voltmeter. i didn't read mv. i set up a fake pid that would read the 2.32 and make it into a fake psi number. the number consistently read 938psi and fluctuated +/- 15. il't give it a better try when i get a nitrous gauge in the next couple of days. don't remember my other values so i'm not sure if the +/- 15 is much on the linear scale.

i can save pids fine if i don't go past tenths in volt input.

 

Got the info from Dean @ Dynotune as well.

This is how the EFI live guys said to set up the PID
(({EXT.AD1} - 2.547) * 20000) = PSI
EXT.AD1 = Voltage from Black wire.

 

Wow, i was just thinking if i could do this today. Perfect timing for me to stumble on this thread. LS1Tech FTW

 

can someone show me how to make a pid like this in HPT?

Beer...what is the " * " asterisk? just an asterisk or "X"???

 

This is how the EFI live guys said to set up the PID
(Voltage - 2.547) times 20000 = PSI
Voltage is from the Black wire.
* is the same as "Times" or "x" or "multiply by"

 

Werd! Subscribing...

 

i'm gonna measure my Autometer signal just for ***** and giggles if it will help you out..

 

I have made a spreadsheet for the voltages vs pressure in excel, based on the DYNOTUNE sending unit...I will upload it shortly.

http://www.retrorelics.net/jim/Board...usUnitPvsV.xls

 

i can't figure out how to make a user defined pid formula like this in hpt.
under eio inputs(aux) you can make a custom pid, its a choice of either a list or linear custom pid which does not enable a formula.

under USER DEFINED PARAMETERS which is for vehicle data, you can set up a formula, but it won't save nor do i know the correct formula!!!!!!!!!!!!

 

Post what you want to do and the formula on the HPT forums (or PM a HPT guru on the board), I am sure someone will point ya in the right direction. I am offshore and will try it with EFI Live when I get home end of April.

For EFI Live I think its a couple line entries in the user calc PID's...I will post what to do with EFI Live when I get it going. I am able to log Fuel Pressure with an Autometer sending unit, its pretty much the same thing with a different formula.

Beer

 

save a log saving only voltages (scrap your custom PID)

then post it up....

 

which voltages are you taliking about?
the car volts or the volts coming from the dynotune sender?

if from the sender, it will probably be a consistent number because the bottle pressure won't change unless i turn the bottle heater on and even that won't yield 0 psi because the bottle is full?

well if you are saing save the volt input to the eio aux, i can do it but according to dynotune, 2.547 is 0 PSI and every .005 volts is a 100 PSI increase up to 1500 PSI.

 

Save a log just recording the voltages from the black wire on the sending unit...

Download my speadsheet and compare the voltages from your log to your bottle gauge, see if they track as Dynotune says the values should be...

Looks like horist will help ya out with the HPT part. Post a log with just the voltages (and what your doing like heating the bottle or maybe a purge) and he sounds like PID it for ya and test it with your log.

Cold bottle nearly full say 50°F I would guess 2.574X for volts. Turn the heater on and watch it increase a bit then purge it should never get to 2.59950 or so

 

You can build a small linear amplifier like this (assuming the voltages here. If not correct, let me know and I'll adjust the values)

 

OK EFI Live Update.

Blacky has said that the logging ability is likely limited to +-200 PSI based on FlashScan A/D inputs are accurate to +/- 0.01V Despite this, I will give it a try next week.

Here is the sample PID for EFI live if anyone wants to try it (Combined input given from Ninety8C5 and joecar; Thanks guys!)

You can delete CLC-00-001 as that is my fuel pressure input




# ================================================== ============================
# File details
# ------------
#
# This section defines various details about the file format.

*FILE

#Parameter Value Description
#---------- ---------------- ---------------------------------------------------
VERSION 7.1.1 File version
DECSEP . Decimal separator used in this file



# ================================================== ============================
# Units
# -------------------
# See sae_generic.txt for more information on the *UNITS section

*UNITS

#Code System Abbr Description
#-------- ---------- -------- -------------------------------------------------------------



# ================================================== ============================
# Add slot definitions here
# --------------------------------
# See sae_generic.txt for more information on "SLOT" formats
#
#Units Low High Fmt Expression
#------------ ------------- ------------- ---- --------------------------------------------------------------

*CLC-00-001
psi 0 100 0.1 "({GM.EGRS}*25)-12.5"

*CLC-00-002
psi 0 1500 0.1 "({EXT.AD2}-2.547)*20000"



# ================================================== ============================
*PRN - Parameter Reference Numbers
# --------------------------------
# See sae_generic.txt for more information on the *PRN section
#
#Code PRN SLOT Units System Description
#------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------
CALC.FP F001 CLC-00-001 psi Fuel "Fuel Pressure"
CALC.NP F002 CLC-00-002 psi Nitrous "Nitrous Main Line Pressure"