I am a bit confused, I have wired in a gm map sensor and made a +12v to +5v converter for it and that works fine. I have an issue going from the map sensor to the lw tuner. I keep getting 36.698 and not the actual pressure. Could my ground be wrong? here is the current full diagram of how it is layed out.

 

So long as measuring from those points you see 5v, should be good. What about the sensor itself though, is there no ground reference point on it?

 

Well as you can see "A" is the ground but it is currently wired to the lw. maybe I will hook up an eyelit and see if attaching the ground to the vehicle changes it.

?? shot in the dark but we will see.

 

Use original wire

 

there is nothing original about any of this.... this is a stand alone system.

 

Pretty sure it should be grounded independantly.. Not positive, it's been awhile since I've piggybacked one of those.. The hose is nice and snug right? And you're sure about the 5v reference being good?

 

pretty sure you need to physically ground that wire

 

finally figured it out... bad wire... x_x