ICP pressure and IPR information
The IPR valve is normally open; it takes a 12 volt pulse width modulated ground signal to actuate the IPR.
-Monitor the ICP while cranking, if it is .4v to .5v (200 psi) it is a possible stuck IPR. The system will build 200 psi even if the IPR is open. Make sure that oil pressure registers on the dash gauge while cranking, if not you may not enough low oil pressure.
-If the ICP is .6v to .7v (400 psi) then it is very likely that you have a high pressure leak
-Compare actual to desired ICP on the scan tool, if actual is below desired.
-If ICP is low remove IPR and check for metal on the screen. If you have metal on the IPR screen then the high pressure pump and IPR will need to be replaced. You will also need to check the screen under the oil cooler, toward the front of the engine valley and clean or replace as necessary. The oil rails and check valves will need to be flushed to remove any debris. Of course the debris may have gotten into the injectors as well and could cause problems with a miss or rough run.
-The ICP pressure should be stable and not erratic. If it is erratic then you could have a high pressure side leak or a sticky IPR valve (requires replacement), or debris in the check valves which will require replacement as well.
-The ICP sensor can leak oil, if this happens replace both the sensor and the ICP pigtail connector
-ICP sensor should read .16 - .28 volts (less than 70 psi) KOEO at normal operating temperature after the engine has been off for at least 2 minutes.
-2004 ¼ and up should be updated to the latest oil standpipe design.