Originally Posted by Houstonvett
The MAP sensor recieves 5 volts from the PCM to monitor the "load" on the engine. IF I remember right the voltage back to the PCM increases as the manifold pressure increases. The way International programs the 7.3 in the PCM allows for a wide range of operating parameters from the sensors without throwing on the check engine light. If the MAP sensor is bad or not reading right the PCM will determine a value for the MAP according to engine conditions it sees from the other sensors. I would check the voltages and see if you do have 5 volts going to the MAP and that the voltage reading does change according to the drop/rise in manifold pressure.
sooo close lol
Hes correct it gets a 5 volt reference signal from the PCM, it then goes thru the MAP and returns on the signal line with a reading from 0-4.9V .. basically anything over 2.5V is usually boost..but on our engine due to no vacuum being created its just there for boost and BARO..
So basically if it sees 2.5V it sends that signal to the pcm, Pcm looks at it and lets say 2.5 = 10psi, it adjusts fuel and timing accordingly..make sense?
However..i havent seen many of these fail.. You have a bigger turbo etc?