If the ICP sensor is attached to both ScanGauge II looks into pressure 575-590 idle.
If, however, the ICP sensor to take off so the pressure is 850-900.
ICP sensor determines the fuel pressure, oil pressure based on?

 

The ICP sensor measures high pressure oil system pressure. High pressure oil ultimately determines the amount of fuel introduced to the cylinder by the injector. Here's a diagram showing the basics.

ICP readings should be stable at idle. If it's jumping around you probably have a bad ICP sensor, or a problem with the wiring going to it.

The only thing that really affects fuel pressure during normal operation, is mass fuel flow. High demand will lower fuel pressure as the fuel pump works at it's limit to keep up with the higher demand.

 

Why are idle in the ICP sensor is attached to the readings about 580?
Should it not be more than 625?

 

580 is not bad if it's stable. The numbers jumping is a greater concern.

 

ICP

Key on engine off = 0

Low Idle = 625.5

High Idle = 1400 - 1450

Operating Range = 0 - 4045

PRESSURE (PSI) ICP Desired

Mine runs at idle about 590 currently. This is after motor is hot. ( At operating temp. )

When I have "WOT" ( wide open throttle ) I have seen it get to around 3800.

Next time I drive it, I'll watch to see if mine fluctuates very much.

This is the first I've seen an "issue" with the variance of readings like you show.