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The ICP sensor is the sensor that measures and reports the high pressure oil pressure. The IPR duty cycle value is a commanded value to the IPR valve, by the PCM, which is used to hold ICP pressure (if the actual matches the desired), or increase it, or decrease it. The IPR % duty cycle command can depend on a number of things, but it has it's acceptable ranges for steady state driving. There is no actual valve position. Just remember, the IPR is a fast-acting, duty-cycled valve. Open/close.
At "cruising", ICP will be around 1000 psig and IPR % duty cycle will be around 30-40 %.
The ICP valve has a screen on the end of it to protect it from clogging w/ trash. If there is much trash, it will clog or even tear. The trash or even the screen can lodge inside the IPR valve to hold it open so it will become a big leak in the HPO system.
New discovery!!!! I filled my truck up to 3/4last night, drove it on the highway for 40 minutes today and it didnt do the rpm drop issue! Not sure if it wqs a fluke or if the issue doesnt happen when I have 3/4 tank fuel or more! Any ideas???
Fill your tank up to at least 1/2 full and test it again. Almost sounds like a fuel suction leak at the pickup foot.
That is why Mark was asking about the fuel level. Autozone does have a tool that will give useful data. The
Scanguage II is about $160ish and you can get them for a bit less with come on line purchase codes. If you
don't mind waiting then there is the ELM device you plug into the OBD2 port and just download some of the
apps for your smart phone or tablet.
I am not. I will run the truck until the issue starts again and then fill it up all the way and see if it goes away. if so I will run it empty then drop the tank
Guess the fuel tank thing was a fluke. At around 1/2 tank the truck started doing the issue again, so I filled it up completely however it is still doing it... back to square one
Get the adaptor for the fuel pressure test port and a barbed fitting.
Then take some clear tubing and run it back to the tank. You may also want to put a small valve in the line.
Be sure to clamp everything. Don't open the valve very much and turn the key on and watch for bubbles in
the fuel. Some other places you can get air in the line from is the the fuel filter car or O-ring and the other place
is the water separator drain.