Reading WB02 with HPT Standard, using AC Pressure Switch

[WickedSS2005]

I followed the how-to here: http://www.hptuners.com/forum/showpo...97&postcount=5

Only I tapped the AC Pressure Switch instead of the pin-out idea like I've seen on a few others that have done this. I can't get the scanner to read. This is the function string I'm using: ([PID.7101]/(5/8.5))+10

The 8.5 is the range I got from the AEM UEGO manual, 10.0-18.5 is the digital readout range.

So, any ideas? Does the cobalt have a different code for the pressure switch?

[WickedSS2005]

Anybody?

[jrocstar]

I had a similar question. I am going to try to access it through a evap sensor and see if that works out better.

[jrocstar]

the sensor needs to be a 5v sensor and am not sure if the ac pressure switch is a 5v reference on the cobalt.

[g5 gxp]

ac is 5v, that is how i have it set up, i have a switch so you can feed the ecm either the actual ac pressure or wideband,

[WickedSS2005]

I had an un-needed space in my function string lol. Problem was solved weeks and weeks ago lol

[damien™]

Wicked, you say you tapped the sensor instead of the pinout. I've found schematics of the ECU Pin outs and located the corresponding wire, just wondering where the actual sensor is.

I'm also curious if tapping the pinout will interfere at all with normal operation of the sensor/skew AFR reading if AC is on.

And what about using a switch, how would I do that?

[jrocstar]

sensor is basically on the backside of the compressor. you must switch it away from ac pressure otherwise yes it will affect the readout. 3 prong switch with middle being the red/black wire going to the pcm and one end coming from the sensor to the switch and the other from the uego's white wire to the switch. that way on way it is running from the uego and the other its running from the ac pressure switch.
wicked what did your filter string end up being?

[bl4des]

ok i am doing this today but i am still unsure about how to get it to work on hpt
where is the easiest spot to splice in the wires

[umrjmac]

there is a writeup around here someone...basically you will log the sensor that youre splicing into the wiring for and then create a custom PID to translate that value into AFR

[Japeatr]

8.5 is your issue

divide the 5/8.5 = .58823 and put the decimal in

[bl4des]

i know how to wire it in i was just looking for the easiest spot without taking the supercharger off i had it off yesterday and dont want to do it again today

[bl4des]

this is the sensor i need to tap into right?

[chris07ss]

You don't need to run a wire down to the sensor. Run the output signal wire through the grommet under the clutch pedal to the PCM, and then add it into the black/red wire in the top plug of the pcm.

I used quick disconnects so that I can quickly switch between my WB and the a/c sensor. Also your fans will run all the time.

[bl4des]

i am going to use a toggle switch so i can change in between when ever
and there is only one red and black wire in the top plug on the pcm right i dont want to be tapping into the wrong one

[chris07ss]

Yeah.

[bl4des]

ok the wiring is all done i just need to zip tie some wires and try to get hpt to read it right

[Japeatr]

chris, why do you say you fans run at all times, my isnt having this issue

[chris07ss]

Well I haven't driven the car since setting up the WB to read, but while I was in my garage idling the fans were on full blast. The WB was reading ~14AFR.

[bl4des]

so i am still a little confused on what i need to do to get it to read the afr if someone had a conf that was already set up that would be great i am going to take a shower and see if i can do it