Was checking ICP psi today and it was a little over 30 psi Key On Engine Off. I cycled key on and off a couple of times and it continued reading above 30 psi KOEO.

Has anyone ever experienced this before or know what could cause this?

I've been having intermittent starting issues. GPR tests out ok. I have to ohm the glow plugs this weekend. Didn't want to get into it this past weekend. I have a E350 and it's a little more of a PITA for me than for you F-series guys!!!!!

Duty cycle/ICP psi are normal on crank and startup above 55 degrees. Van fired up tonight no problems. Ambient air intake temp and oil temp were 64 degrees tonight.

 

ICP can read 4000 PSI with a computer using 255 increments to do so. That's over 15 PSI per "point" of resolution, so 30 PSI is nothing more than two points off zero for that sensor. Think 0.2 ohms while reading a wire on a cheap multimeter, or a notch below "E" before running out of fuel.

 

Translation; these sensors are not perfect. A stray bit of voltage here and there will fuzz up the readings. Big picture, overall, Ford and/or IH decided they are fine for their function. But for granular detail you'll need expensive calibrated sensors, and that just isn't happening in a consumer item like a car. Unless it is critical and the corporate bean counters see the light.

All that said, inspect the harness at the ICP sensor closely, maybe the wires are ugly. Pull off the connector and see if it's oily, sign of a failing ICP sensor.