Reading Boost

[KEVINS]

I have a 0-5V xdcr that reads 0-100psi which is what I typed in the Diablo but at idle/cruise the graph shows that it's making 11psi.
I believe the upper boost reading (24psi) is accurate but not sure.

How do I correct this?

ks

[KEVINS]

I thought I figured it out but guess not. Initially I had the "SIGNAL GROUND" from the XDCR connected to the sheet metal of the car but I changed it today and connected it to a Signal Ground from the cars computer. This gave me different reading but now it's reading 13psi of boost at idle..

The AEM unit has the below specs:
0.5V = 0.000psi
4.5V = 100.000 psi


I don't know what I'm doing, if anyone can help me I'd appreciate it...aarrgg..

ks

[mikel]

2 things...

1. is it trying to show atmospheric at idle?
2. Have you tried the built in boost gauge on the trinity?

[KEVINS]

2 things...

1. is it trying to show atmospheric at idle?
2. Have you tried the built in boost gauge on the trinity?

Thanks for replying.

1. No clue. How do I verify and modify this if it is?
2. I don't have a Trinity so I haven't tried anything beyond trying to get the xdcr wired properly and making two different logs on the Intune.

ks

[mikel]

OK, my bad, not sure why I thought it was trinity.

I have never used a pressure gauge but base atmospheric pressure is usually ~14.7 psi, so you may need to compensate for that.

[KEVINS]

OK, my bad, not sure why I thought it was trinity.

I have never used a pressure gauge but base atmospheric pressure is usually ~14.7 psi, so you may need to compensate for that.

OK.. That makes perfect sense.
Now the million dollar question: How/where do I compensate for it? Any detailed tutorial I can read in order to get this reading correctly?

ks

[mikel]

Id check the the sensor manufacturer or others who have used this sensor as an analog input.

[KEVINS]

Id check the the sensor manufacturer or others who have used this sensor as an analog input.

Now you're losing me: You think the sensor itself is not reading correctly...?

Here's the link to the data sheet for this xdcr:
http://aemelectronics.com/files/instruc ... 20Data.pdf

ks

[mikel]

no, the sensor is reading correctly likely, but showing atmospheric pressure.

I have no experience with such a sensor so I am suggesting that you contact the sensor manufacturer or others who have used t to measure boost.

[KEVINS]

I called AEM and I currently have it connected properly which is good.
I'm going to see if there is some voltage on the output wire at idle although there should not be any. If there is about 1V at idle then this equals about 15psi.

ks

[KEVINS]

no, the sensor is reading correctly likely, but showing atmospheric pressure.

I have no experience with such a sensor so I am suggesting that you contact the sensor manufacturer or others who have used t to measure boost.

If I verify that there is no voltage on the output wire but the Intune is still outputting 15psi, is there a way to zero it or change the Intune so that 0V is 0psi in stead of 15psi?

Once I get this taken care of I may have to do the same thing with the methanol pressure xdcr.

ks

[mikel]

No, thi si snot an intune or dv issue, the tool simply reports what the device says is equal to the corresponding voltage...if it wants to display 15 psi at idle, we cant change that.

[KEVINS]

No, thi si snot an intune or dv issue, the tool simply reports what the device says is equal to the corresponding voltage...if it wants to display 15 psi at idle, we cant change that.

Gotcha. Hopefully there's some voltage or ?? that's showing up causing the funky reading.

ks

[KEVINS]

No, thi si snot an intune or dv issue, the tool simply reports what the device says is equal to the corresponding voltage...if it wants to display 15 psi at idle, we cant change that.

The device is registering .7 volts at idle and it should be .5 volts so this is part of my issue but this brings up a question:

If this devices minimum voltage is .5V there is no way that it will ever read 0psi of boost b/c the Intune is preset to read 0V, correct?

If so then this is a complete waste of my time and effort to try and log any pressure like boost, Meth pump pressure, etc b/c these all begin at 0.5V.


Can anyone recommend a 0-5v xdcr that reads 0psi to 35+psi???
OR can I send in this Intune and have it set to .5-4.5?

ks

[KEVINS]

The more I pull my hair out the clearer things may be getting...

Using a GM 4BAR MAP sensor should be what I need, CORRECT????? Don't these operate at a true 0-5v???

ks