[lostboyracing]

Hi all. Been lurking on the forums for a while but haven't had the need to post a question until now.

I'm currently in the process of setting up a fuel pressure sensor for logging in BE, on a 1998 Mustang GT with CRAI8 strategy. I have it wired into the EGR circuit (brown and light green wire, pin 65 on the EEC) but I'm getting some odd behavior from the BE displayed value. I have it wired to a gauge as well, and that is displaying correctly. The BE PID that I hijacked is DELPR and I have the transfer function set up per the pressure sensor data sheet. The dashboard in BE displays 150 PSI on initial startup, then essentially counts down to 0 PSI over ~30 seconds or so. During that time the gauge on the dash displays 39 PSI which I believe to be the actual value (previously set the pressure at the regulator with a mechanical gauge). Anyone have any insight here?

[jsa]

Log iEGR PID at address 0x152, alternatively try 0x804 or 0xDDE.

The CRAI8 strategy document says Pin 65, if you have traced the wire to Pin 67 ignore the document.

[lostboyracing]

Log iEGR PID at address 0x152, alternatively try 0x804 or 0xDDE.

The CRAI8 strategy document says Pin 65, if you have traced the wire to Pin 67 ignore the document.

Nope you are right, it's pin 65, my mistake. Edited in my original question.

[lostboyracing]

Log iEGR PID at address 0x152, alternatively try 0x804 or 0xDDE.

The CRAI8 strategy document says Pin 65, if you have traced the wire to Pin 67 ignore the document.

I tried stumbling around BE to figure this out, but I'm not sure how to log a PID via an address. I haven't been able to find anything called iEGR in the available parameters list. Do I need to set up a user defined PID?

[jsa]

Yes set up a user PID if you are using a CRY definition.

0x152 will need a logging patch already in place. The alternates wont need avlogging patch.

[lostboyracing]

Excuse my noobness, but what is a logging patch?

[jsa]

The logging patch copies CPU register addresses to RAM addresses so that the QH can access the parameters from the CPU register address range.

If you are using a CRY type definition then it is up to the author to include the logging patch. Ask the author if it has been included.

0x152 is a CPU register for 8065's.

[lostboyracing]

Hi John- I created a UDP for all 3, but only 0x152 outputs data. It fluctuates between 192, 128, 64, and 0 in a seemingly random order. I have the PID set up as follows (and no idea if this is correct):

Bytes: 1
Signed: False
Equation: X
Digits: 2
Units: X

BTW I am using the definition file provided through CoreTuning. Not sure if this is a CRY type or not...
What am I expecting this to show me? Thanks for your help thus far!

[jsa]

It is a word so 2 bytes.

For 0-5V set equation as X /13107 or change it to suit your sensor units.

CRY type then.

It'll show counts until you change the equation.

[lostboyracing]

Thank you for all the help so far! I feel like I am 90% of the way there, with maybe some fine tuning of the transfer function left. Right now I am getting a difference between what the gauge reads and what the dash displays in BE, on the order of 2-3 PSI. I can't tell for certain, but the delta doesn't seem to be linear. Seems smaller at lower pressures, and larger as pressures rise. I'm only able to monitor the range between 0 and 40PSI, which is where the AFPR is set. I tried watching the gauge and laptop dash while driving, but it was tough to tell...

My equation is currently set up like this: ((X/13107.2)*(150/4))-18.75

My logic is X/13107.2 converts the ADC output counts to Volts. Then multiply by the slope, and subtract 18.75 PSI because of the 0.5V offset at 0 PSI. The units seem to work out in the equation, but I feel like I might be missing something. The sensor I'm using is 0.5V-4.5V output for 0-150 PSIG. Does the equation look correct?

[jsa]

Your equation looks ok.

It's not unusual to see differences, so it's a case of calibrate the input to suit whatever you believe to be the correct values. If the error is linear it's not so difficult to adjust.

Change the equation so that it is easier to calibrate. First adjust the zero point with zero fuel pressure by adjusting 6553.5 until BE reads Zero. Second adjust the span with fuel pressure by adjusting 349.52 until BE agrees with your expected fuel pressure.
(X-6553.5)/349.52

0.5/5=0.1
0.1*65535=6553.5
150/4*5=187.5
65535/187.5=349.52

[lostboyracing]

Would it be necessary to do this on a day when the barometric pressure is 1 atm?

I'm thinking I will use the Innovate digital gauge as the "calibration" comparator, it will be my aiming point for determinimg these compensations. It makes my brain hurt to trust their readings without verifying, but I suppose being a gauge manufacturer their stuff is close enough.

[jsa]

No it should not be necessary.

Yeah, Innovate, I don't trust their stuff either. Best you can hope for is BE reading being the same as the gauge.