Been looking for the info on this in my Helm set with
no luck, nothing on the Delphi web site either. I want
to determine if the readout voltage matches the
gauge pressure of the system (100PSI, 3.71V).

My scan tool only shows the volts.

Anyone got tech info on this?

 

hmm i will have to check, i know my tech 2 shows voltage vs. pressure. I have to watch the kids now, but i will do some checking and get back to you.

 

I believe your sensor voltage is being reported incorrectly.

I just went out to my car, (car was driven 2 hours ago) and the voltage was 1.3 engine off with efilive

Once started, the voltage went up to 2.8 volts

I was unable to get the pressure using thier scanner.

Using this logic, the 3.7 volts, may be an over pressure condition for AC clutch enable, the information I have says the minimum pressure needs to be 39 psi to enable the clutch, and disable the clutch at 414 psi, but may require the high pressure to be under 249 psi to enable the clutch if the clutch is already off.

With the compressor clutch override with hptuners, did the voltage change?

Ryan

 

The voltage didn't change. That made me go out and
buy a sensor. So earlier today I had a new sensor
to swap in, but plugging it in dry / open, still the same
reading more or less. So this implicated the wiring.

At the connector, plugged in:
Gray wire 5.00 (good)
Red wire 3.77 (matched reading)
Purple wire 4.16 (not good, should be 0.00).

Turns out that when I relocated the IAT the other
week, the purple IAT GND wire I cut, is also the GND
feed to the A/C pressure sensor. The GND there was
floating up to 4.16V and the output was apparently
following this, but held down by some clampage
internal to the PCM. I cut it too close to the PCM.

So made it a "T" instead of a cut-n-swap, and all
better now.

I got some info from "EC Tune" over on the HPTuners
'board, and put into a small Excel 'sheet for others
who may need it (.zip'd attachment). It pretty much
lines up with your numbers (thanks).

 

I'm getting an invalid archive error trying to open your attachment. 1.7KB is a pretty small compressed spreadsheet

 

It works for me.

jimmyblue,
Were you able to make a formula to convert volts to PSI or
did you use a lookup function with the values in the sheet?

 

I got a formula (EC Tune's custom PID) and just transcribed it
(and figured its inverse).

Spreadsheet only has about 10-15 live cells and was Winzip-8
archived. It downloads, unzips and opens OK in Excel for me
from here.

 

How odd... if I use IE7 to save or open it directly, it's unreadable with either XP or WinZip10. If I use Firefox, no problem.

 

What is the formula?
V*?

 

I am unable to open it as well.

The sensor is not a linear sensor, close, but not linear at the end of the range.

Ryan

 

It fails for me too in MSIE, but opens fine in FireFox. I've
got to figure out which computer I saved it on and I'll upload
another copy via MSIE.

This is what I originally got from Doug (EC Tune):

Here's my custom PID for that...
Name: AC_Pressure_Calc
Abbr: ACPressC
Units: PSI
Function: [PID.7101]*93.48625-15.5388
Got all of this off a Tech 2.

All I did was put it in a spreadsheet so I could what-if.

 

This attachment was uploaded via MSIE, it is
(on the hard drive) the same as previous.

Downloading with MSIE I still get an invalid archive beef,
whether direct-open or save-as. Archive opens clean
on the PC. I think this may be a site or MSIE problem.