Originally Posted by
kingtal0n
Follow the vacuum line from the intake manifold to the map sensor.
This line is the most important line on the car.
Map sensor needs a dedicated vacuum line, NO T's
It should run to a trusted intake manifold source. I usually have a map barb fitting welded on the back of the intake manifold.
You can check the vacuum signal with a gauge, a vacuum gauge or boost gauge (Which reads in Inches of Hg) to make sure the map is seeing vacuum.
In the computer the map sensor signal on a running engine will fluctuate constantly. Don't run the engine until this is solved.
For example mild cammed V8 will pull 15" Hg at idle. That is about 50KPA on the map sensor.