I haven't posted very much but I recently had an issue that I couldn't figure out. My truck would start fine and ran great until it was running for awhile, especially if I let it idle for 5+ mins at normal operating temperatures.
After idling, the truck would buck/surge/miss and stumble. I could cut the truck off, let it cool down to ambient, restart and it ran fine. I posted here 06 F250 6 CEL Codes NEED HELP
and I attempted some of the things that were suggested.
Then, I got to thinking. Diesels don't have ignition systems (spark plugs etc) so if it is missing on a few cylinders then its either missing air or fuel, or possible compression. So I started researching here at Powerstroke.org on what the main components of the injection systems are.
As you all know, the HPOP is the foundation of the injection system. Impossible to diagnose without proper tools so I just had to hope that wasn't it. I got had on the warranty of a 1 week old truck (dealer pays 30% total, only in his shop which has no previous diesel/powerstroke experience.)
Next is the injectors, at least a few hundred dollars a piece I had to hope they didn't fail. With the good starts and good running while cool, I figured it wasn't the injectors, I know, I have horrible deduction methods but I'm just an old country boy with some basic hand tools and a multimeter.
So on to the final idea. The FICM. Unless you really dig, on the surface the no-start/hard-start seems to be the tell tell sign. My truck started great. Also, a few diagnostics threads never even mention testing the voltage with key on engine on. So, key on engine off I got 48v. Next test, on a hunch and 1 youtube video, I started the beast and tested. I got 30Volts definitely not sufficient to drive those 8 injectors.
This lead me to my final find, Upon removal of the FICM, the plugs were slightly damaged and the two injector plugs had a very poorly done sealant job that was *supposed* to keep the tight in the FICM. I wiggled the plugs, NO START. Wiggled them again, Start with miss (which was my final result after driving it home from the last idle/miss situation.
So, I pulled the FICM apart, the power side smelled like ozone (burned electronics). I have ordered a new power side board for 169$ this morning.
I will let you guys know if this fixes it. I may end up ordering the plugs and just go ahead an rebuild the injector harness to eliminate connection issues. Thanks to those folks who offered advice. Hopefully this thread may help someone else with the same issues.