Late-build 2004 With Intermittent Runs Rough/Stall

[mchan68]

I have a late-build 2004 F-450 4x4 that recently had a grocery list of work done (ball joints, rear brakes and axle seals, transmission service and coolant flush etc.) also with a complaint of the engine running rough and stalling. Only DTCs set during that visit were random cylinder contribution codes in memory. After being unable to duplicate the symptom and completing all that work, I let it go. About a month and a half later, the vehicle returns with the same complaint. Again, all I got were random cylinder contribution codes in memory, but different ones this time. After driving the vehicle for an hour being unable to see anything out of whack, again I released the vehicle. When the customer came to pick up the vehicle, he requested a quote to replace the fuel pump. A week later, he brought it back to have it done. Today, when he came to pick the vehicle up is when it started acting up. So, I rush in to grab IDS to look at some stuff. I quickly notice that power balance is all over the place, but NOT misfiring. Upon, loading up my favourite 6.0L PIDs to look at, I quickly notice that IPR duty cycle is at 32% at hot idle with ICP psi at 580 psi as well as ICP desired. I try to "toggle" IPR back down to 24% and the truck quits. ICP volts at KOEO indicates 0.23 volts. I tried wiggle testing the IPR connector as well as the ICP sensor connector while it was running with no change or reaction. I then restart the engine, and ICP desired and ICP psi immediately shoot up to 870 psi with IPR at 32% and the engine running rough. Give it some throttle and let slow back down to idle and now life is good with ICP back at 580 and IPR at 24%. Soooooo........ what do you guys think? ICP or IPR? Vehicle has no trouble starting when the engine is hot at all, so we know it has no high pressure oil leaks.

[slim]

It sounds like the high pressure oil system was in failure management mode with ICP and ICP desired reading the same with a high IPR duty cycle, if I'm reading that right. Since the ICP was reading correct after running up the RPM I would guess the IPR is sticking, maybe R & R the IPR and check the screen. Good Luck

[Mbl35]

I had 4 like that, the last one it was doing it constantly, it was rough at idle and the power ballance was all over the graph when you rev it up, it was overfull with oil by 10 quarts.

The other three were ipr's-last one being an 08, came in on the hook with dead batteries, needed alternaters. After the repair i took it on a test drive when i noticed a slight hesitation on the highway, power ballance showed misifires jumping from cyl. to cyl. I rnr the ipr after high pressure oil airleak test passed. The screen had a little hole in it. The other two also needed ipr's.