AEM 3.5bar Map Sensor - Calibration Table Help

[Daniel Sabler]

Hi,

I´m using an AEM 3.5bar Map Sensor in a Skyline R34 GTT (G4 Plug in).

The correct AEM constructions are beginning:

Volt     PSI

0.5     -14.7

0.75   -11.575

1          -8.5

....and so on.

But in the calibration table I´ve set:

Input Units = Volts

Output Units = PSI

Output Table Start = 0 PSI  (the Problem!)

Output Table Increments = 2

--

The problem: how can I set the 'vacuum / negative PSI' like -14.7 at 0.5 Volt? The software only allows to start with 0 - not with any vacuum / negative PSI...

[Steve1436215419]

Im using KPA on my car but that doesnt matter i assume. I use that sensor to.

My calibration table starts at 0 to and ends at 345 kpa. 0 is really 100 kpa vacum so 100 kpa is actually atmospheric pressure.

In your case 0 psi is 14.7 psi of vacum and 14.7 is atmosphere.

We are dealing with absolute pressure here not gauge pressure.

[Simon]

You will be better to scale the sensor in kpa as the rest of the software is geared to be in metric readings.

Most sensor are linear in there output so you shouldn't need a cal table. Just use a point A point B cal.

[chris164935]

Bumping this thread.  I have an AEM MAP sensor as well, using the point A/point B cal setup, will I be able to see vac readings on my digital display or will it just read 0 and I have to do the math in my head?  And if my display says I am pushing 20 psi, it is actually 5.3 psi absolute (20-14.7)?

[Simon]

The Cal will be in absolute.

so 0kpa = 100% vacuum 

100kpa is roughly atmosphere

200kpa = 1bar or 15psi

Attached is a image of a correct cal

[chris164935]

Awesome.  Thanks for the help and fast response!