Map not changing with throttle position could be an issue...... Can you apply vacuum directly to the map, and see the signal change?

 

Vacuum reading does not change, no. I'm thinking its a problem with the scanner though, unless the PCM isn't converting it into inches of vacuum. But both computers do the same thing.
It's a 3-wire sensor, it communicates to the PCM via a voltage change depending on the vacuum reading, right? I can see the voltage changing, even on the scanner, but it has a reading for vacuum, which does not change.

 

You are correct on how it is supposed to operate... I am real curious why the PCM doesn't think pressure is changing though. That's not quite right. That isn't for barometric (atmospheric) pressure by any chance is it? (I don't think our trucks have a baro sensor though..... I've never seen one.....)

 

Map sensor is for reading air density. It tell the pcm where you are (sea level or high up in the mountains) for correct air fuel mixture.

 

Barometric pressure sensor there.

MAP sensor is "Manifold Absolute Pressure." Reading should change with engine vacuum.

 

Does not change, but voltage changes, this really makes no sense....I'm gonna throw on in tomorrow.

 

Yes barometric! voltage should change with different vac readings.
http://www.aa1car.com/library/map_sensors.htm

 

Ya, voltage does change but can't see a vacuum change on the scanner. Ordered one for tomorrow, will update with the results.

 

New map sensor, no change. It can't be this hard....I have everything I need,Nagy does it not run?

 

Just out of idle curiosity, what spark plugs ya got in there, and how old are they?