ok. if the ICP is just bad. not reading at all, then the PCM goes to the default setting and has the rougher idle. now when you unplug it, the idle gets smoother? the sensor could be reading incorrectly causing it to run rougher. if you have oil in the plug then you need to repalce the ICP

Scan it and quit playing the what if game...

It's not a game. It is a discussion. Intelligent people engage in conversation. You obviously have a closed mind. I embrace even hypothetical questions. I sometimes ask a question I think I know the answer to in order to stimulate conversation and maybe learn something. Does this bother you?

Is this your only source of entertainment? Do you get your jollies by trying to belittle others and trying to sound smart? Every time you respond, You sound more and more pathetic. It's hard to believe Dieselbombers tolerates you. Who would want to ask a question knowing YOU might respond? It has to be bad for business.

What part of "go away" do you not understand? Do I need to type slower?

Parts are expensive. Throwing parts at a truck without knowing any data is a path to cause more issues.

James is giving you sound advise.

You could have an injector issue, you could have an injector O ring issue. You could have a HPOP issue. You could have a LPOP issue.

ICP sensors fail very rarely. If there is no oil in the ICP sensor they are typically fine.

If it runs rough and then unplugging the ICP sensor smooths it out, that could lead you to a ICP sensor issue, because the truck will now be running on default pressures rather then erroneous readings coming from the sensor.

BUT...

Assume you unplug the icp sensor and it starts running smoother, then you think "ok, there is my issue" and you replace the sensor with another or a used one. Fire the truck up and its still doing it... "humm"

Now it could be the replacement ICP sensor, or it could still be an injector, HPOP, LPOP, Oring or other issue. You have just added one more WHAT IF into the equation.

What does it mean when there is oil in the ICP?? Just curious..

It just means the diaphragm is leaking, which gets into the sensors parts and causes them to fail. I have one I use for a spare that has oil in it, still works, but long term it would fail.

which i'm going to be replacing mine pretty soon. oil is in the plug but it still works so it will be a spare :tu:

The advice is sound. If I was in a hurry, I would opt for the scan. I can use the truck the way it is for now. I've decided to take this opportunity to learn as much as I can. I am a very curious person and enjoy asking "what if", and taking chances. In my opinion it is a good way, and sometimes the only way to learn. When someone tells me to do or not do something, I want to know why and how. If they can not or will not tell me why or how, I will experiment and consider finding out the only way left (the hard way) to satisfy my curiosity. Don't get me wrong, I would prefer to pick a persons brain and be convinced by reason. I hate being told "I told you so" by an arrogent person who was unable or unwilling to say why or how. I'm asking for more then advice here... I am asking to be taught

Can I eliminate the LPOP by noting that the reservoir is always full?

Can a scanner differentiate between not building pressure (HPOP) and bleeding pressure (injector/o-ring)? (assuming a good ipr and icp) and if so, how? Knowing this may help if and when I get it scanned.

If anyone reading this even thinks they can contribute, now is the time. If you you have the same or similar questions/curiosities, say so. This could benefit many and I for one will be in your debt and you will have my humble thanks.

Thank You CSIPSD. i have come to appreciate your prowess and you have my
admiration.
fordornothing, thank you, you are helping.
95powersmoker, I sincerely apologize... and thank you.

I'll give you my thoughts more when I get home or tomorrow... I am taking the kids to a movie and then back to the NICU tonight to give my wife a chance to take a nap with our new girl!

CONGRATULATIONS!! We spent way too much time in a NICU with our "twin boys". Is she a preemie or are there other issues? My family will pray for yours. I cherish the time I spent at the nicu in a recliner with one of my naked babies sleeping on my bare chest. (It's a bonding thing).