Join Date: Oct 2013
Location: West Palm Beach
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[SOLVED] LIMP MODE, 04 6.0 limp-mode, derate mode, de-fueling... please help
Long time reader, new member because im really at a loss. I got a 2004 F350 6.0 that's going into limp mode, or derate mode, or de-fueling whatever its called. when the truck reaches operating temp it wont rev past 2500 rpm, has plenty of power, and I can still drive on the highway, if I shut it down and restart its fine for several seconds, does it again. it never fails, if I drive easy the whole time or if I beat that crap out of it once it warms up it goes limp (that's what she said). ive heard multiple opinions on what would cause this. the truck is completely stock with the egr unplugged (it was doing it before I unplugged the egr), and no check engine light and no codes stored according to my scangauge 2. here is what ive done/checked so far.
replaced both fuel filters (autozone, was doing it before filter change)
Checked FICM voltage, doesnt drop below 47.5v
Checked FICM sync, in sync (1)
checked oil pressure, 590psi at idle, almost 4000psi at WOT
checked boost, 0-3psi at idle, just over 20psi at WOT
checked fuel pressure, 56-58psi continuously
checked ECT and EOT, when it went limp EOT was at 158 degrees, ECT was
at 166 degrees, but both stayed reasonably close together
checked MAP sensor, idle 15.1, high idle was the same, WOT went up to 21 before I had to let off the throttle
checked EBP sensor, idle 17.1, high idle 18.9, WOT went up to 32 before
I had to let off the throttle
I really don't know what the MAP and EBP readings mean
I don't really know what else I should be looking at, and help would be really appreciated.
SOLVED: BAD EBP SENSOR - truck thought it was boosting 40psi
Last edited by mkeevo; 01-22-2014 at 11:59 AM.
Reason: change title, added ficm voltage and ficm sync