Hey everyone. I was seeing if my icp sensor was bad or not. I went to unplug my icp sensor while it was running to see if the idle smoothed out, and the truck died. I plugged the icp back in and it started right back up. Just wondering what this means? The truck is a early 99 f250 with a 150k on it.

 

My guess is that ICP drops too low with the sensor unplugged, possibly due to a leak in the hydraulic system. You'd need to know what the actual pressure and IPR duty cycle is to confirm that or rule it out. Do you have access to a scan tool that will read live data?

 

I'm with our cartoon friend here, it sounds like an internal oil leak or a bad IPR. Injector O-rings step forward in the suspect lineup.

 

Just curious here. What should happen when you unplug your ICP, in regards to a PID reading on Torque or AE? Would the ICP value indicate the default (725psi IIRC)? My truck continues to idle without it, but my Torque ICP readings still show what appears to be normal values. And what does the IPR then do, or what is it told to do?

 

Why unplug it while it's running?

If you're suspecting problems, unplug it and THEN start the truck to see how it runs.

Unplugging while running is not the correct diagnostic approach because it is not a rare occurrence at all that the engine will stall, even if nothing is wrong with the sensor or the HPO system.

 

ICP will read 2200 PSI while cranking and 700 PSI while idling. The IPR will go to a level it expects to work in each situation - about 30% while cranking and 14% while idling.

 

Does the early model hpop make less pressure? because if i remember right mine was at about 500 while idling.

 

500 PSI when idling is with the ICP plugged in and working correctly, unplugged it will idle at ~750 PSI based on IPR.

 

This is good info, thanks fellas.

 

The recent history on my truck is a new T500, new injector o-rings, new stock turbo, new RR bellowed up-pipes, and I'm currently working on a low fuel pressure problem, ~40psi max. I just received the FPR rebuild kit, but haven't gotten to that yet.

The truck had been running until last Tuesday, when I went out of town and it sat all weekend until last night when it first quit. Thought it was CPS, but it seems to have been a fried battery cable, but now I have this.

Mostly, very low ICP, about 230psi max while cranking, IPR goes to 60-65%, and FIPW seems to jump around a lot. If I pull the ICP plug, my pressure does hit the 2200 range, but still no effect on starting.

If I let it sit awhile, it does restart, but ICP remains very low while IPR starts climbing.

 

Got her started again, trying to move her into the garage, instead of outside in the rain... anyway, about two minutes of run time, but again no ICP, and then no restart.


But at least I finally figured out how to get inline pics in here.

Again, except for low fuel pressure, it seemed to run okay last week, and even for the 5 minutes last night down the road to the dumpster... then it just wouldn't restart. Since the HPOP is new, as are the injector o-rings, I'm guessing the IPR? I had one no start several weeks before I replaced the turbo, due to low ICP while cranking, and that's why I went for the T500. That and it was just staring me in the face during the turbo pull, daring me to replace it.

 

Given the work that's been done, including replacing the HPOP and injector o-rings, I'd have to say the next most likely cause is the IPR.

 

Can the tin nut be too tight? It's not moving, the solenoid isn't loose (had that once long ago, where the solenoid could wiggle around on the thingy that goes into the HPOP), but if the nut isn't distorted, can it be too tight? Can I pray that I was overzealous in putting the thing back on the HPOP?

 

It will strip if you get it too tight.

 

No, I didn't strip it. I installed it while the HPOP was on the bench, which meant I was able to get right at it. Just wondering if it could affect the workings of the solenoid. I don't see how, but there are lots of things I don't see. Just ask my wife. :-)