LIMP MODE, 04 6.0 limp-mode, derate mode, de-fueling... please help

[mkeevo]

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.

fresh oil/filter
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.

 

[Gary]

Try to clean the EGR and see if that helps.
I don't think they de-rate, de-fuel or have a limp in mode.

 

[POWER-STRUCK]

my guess would be to check the transmission fluid temperature sensor, if it is an auto

 

[fordfreak4life]

Had one do something similar, plugged cat was the culprit

Sent from my Milestone X2 using Tapatalk 2

 

[02POWERSTROKE7.3]

I had one with a plugged cat defuel like this last week.

 

[mkeevo]

Try to clean the EGR and see if that helps.
I don't think they de-rate, de-fuel or have a limp in mode.

They do have limp mode. The egr is clean and unplugged

 

[mkeevo]

my guess would be to check the transmission fluid temperature sensor, if it is an auto

I talked to a mechanic at Navistar/International and I was told if it's the transmission it would shift different, no overdrive, and tow/haul light would be flashing. Which is not the case

 

[mkeevo]

I had one with a plugged cat defuel like this last week.

How would I know if it's the cat. I've seen bad cat's in gas cars they if they even start they barely run. This thing runs great until it goes limp

 

[02POWERSTROKE7.3]

Pull you down pipe loose at the turbo.

 

[mkeevo]

Pull you down pipe loose at the turbo.

So just pull the exhaust right off the turbo and run it. That won't damage the turbo in any way?

 

[02POWERSTROKE7.3]

So just pull the exhaust right off the turbo and run it. That won't damage the turbo in any way?

Yeah, won't hurt anything. Just drive it normal so everything doesn't get covered in exhaust soot

 

[sootie]

Any codes?

 

[mkeevo]

Yeah, won't hurt anything. Just drive it normal so everything doesn't get covered in exhaust soot

I wasn't sure if it needed to be connected to help with heat transfer or something. Ok I'll give it a try this weekend

 

[mkeevo]

Any codes?

No actual codes. Unsure of soft/pending codes

 

[Gary]

They do have limp mode. The egr is clean and unplugged

I've never seen a 6.0 in "limp mode" I know the 5R110 trans has a "safe mode"
I've seen 6.4's and 6.7's that were in "limp or safe mode" because of rail pressure codes if I remember right.
What codes will a 6.0 have if it's in safe mode?

 

[mkeevo]

I'm at a loss.... It's going to Ford tonight

 

[Gary]

Do you know 100% that you scanner is communicating with the PCM? What is your fuel pressure, FICM voltage and is it making boost? Watch your data stream and see if it goes out of sync when you have the problem.

 

[mkeevo]

Problem was bad EBP sensor. Truck thought it was boosting 40psi.