So I'm wondering, logging boost on a car w/o a boost gauge, is it possible to use the map sensor? OBD2 scan tools generally use inHG so (x*0.491)=psia? then (psia-14.7)/100 would work?

 

erm... The ECU has a built in Boost monitor... You only need to know the RequestID/how to access the sensor with your app/tools...

In EvoScan:
requestID: 2380872E

 

For the sake of argument pretend that this isn't a Ralliart.

 

Logged boost via OBD2 will be capped unless you use Mode23 MUT logging.

If I remember correctly, it will be capped at 23psi.

 

it seems the MAP sensor on the ralliart tops out at 37.2inHG(18.3ish psia) so I'm not sure how well that math works out... Though some people on turbo diesel domestics don't seem to have this problem.

I see a few wrxs and older gm 3.8 super charged cars where I work so being able to watch the map readings if there isn't a gauge would be helpful.