So I've just been reading around and I was curious as to what a map sensor actually does. I'm in auto class at my vocational school but we never really talked about this, I just want to know what they do, where they are and what the diference is between a 2 and 3 bar is and what "pigtails" are. I own an 06 lsj and I also heard the map sensor actually reads what the boost is. Any info would be helpful, thanks!

 

map = manifold absolute pressure, basically tells the computer how much vacuum/boost is in the manifold.

 

Each "bar" = is capable of reading 14.5 PSI of boost.

So a 2 bar can read up to 29 psi and a 3 bar can read up to 43.5 psi.

You really dont have to worry about the "pigtails" because that pertains to the LNF with the GMS1 sensor upgrade.

Your stock sensor is a 2.5 bar MAP sensor which also reads your air temp in the intake manifold too.

 

So this is where the boost gauge gets it's reading from as well?