1999 Dodge 5.9L 24 v/v Turbo Cummins. Problem developed suddenly. Won't raise above idle without severe missing/hesitation. Trouble codes point toward fuel injection pump valves. Verified that lift pump is supplying adequate pressure and volume. Noticed during scan that MAP sensor voltage is only 0.45V key on engine off and does not change on start up. Supply and ground to MAP sensor tested and OK. Would like to bench test the sensor, but do not have any specs other than to blow and suck looking for voltage changes. On the surface the problem seems fuel related, however the MAP voltage being out of parameter is certainly curious. Does anybody have any ideas. Thanks for the help it's greatly appreciated.

 

I believe the "map" sensor in this application is more for monitoring boost and wouldn't have that much effect on idle. I could be wrong here, but I'm not really sure. I would lean towards a pump issue. Does it change the poor running condition if you leave it unplugged (default)?

....duhhhh, how easily we forget. Deisel has no vacuum so the "map" sensor is only going to be used as an input for pressure. There will be some reading because they use it for an input for ambient psi which is usually around 14.7. I remember waaaay back watching boost on the drb while driving and seeing manifold psi around 34-35 psi at wot with a load. Found you had to subtract the atmospheric psi reading from the boost reading to come up with the correct actual boost number.