Pluged in my little reader and went for a drive!
Map reading maxed at 37.7
Is this normal?
Cant help but notice this is 23 psi over atmospheric.
Truck works okay just curious!

 

The ECM reads the absolute pressure, so you'll need to subtract atmospheric from it to get the boost reading. 23psi sounds about right if you were getting after it. Now if you see that at idle, then you may have an issue.

 

Yes it does show around 14.7 at idle.
So does the map sensor max out at 37.7 or is that where the wastegate would be set at?

 

I'll take an educated guess and say the wastegate is set to open around that pressure. That would be about 23psi of boost, which sounds close to the wastegate value. But someone with more 3rd gen experience may know for sure.