Won’t rev over 2k

6.0 Tech · Jun 18, 2021

bismic said:
Could the intake manifold be plugged up (from when the EGR system was active)?
Done any tests on the VGT solenoid?

No, we put a new Odawg intake on it when it went together. Vgt solenoid is working properly.

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6.0 Tech · Nov 19, 2021

Well, finally got back around to this truck. I was leaning hard on a spun cam gear, pulled the motor, we had put a welded one in. Verified timing was right. Nothing in the bottom end goofy. Pulled the heads, found a bunch of soot in the passenger side of the intake, and all the intake ports on the passenger head were dirty from spot. Once I got the head off, found 3 bent exhaust valves, held open about 1/16 of an inch. All the pistons got valve marks on them. These were somewhat unknown heads we put in it, so I’m guessing the valve springs were very weak. Probably going to be putting a new set of kdd heads on it. Or maybe a used set off our race truck, gotta see what he wants to do.

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6.0 Tech · Dec 24, 2021

Ok, we’ll got a different set of heads put on, they’re a used set off our race truck, but have had a fresh valve job done on both heads, valve springs are now 120#, known springs. Truck still runs like dog ****. Still leaving a pile of soot on the ground, and won’t rev over 1200. Had misfires on 1&5, verified pushrods were seated right, and swapped injectors with a couple new ones, still runs like dog ****. On a wild ass guess, I checked converter slip, computer was indicating it was locked. At idle actual slip was 15-55 rpm. I know it shouldn’t be an issue in park/neutral, but I’m throwing logic out the window at this point. Pulled the trans, still runs like ****.

Anyone got any more ideas? I think on Monday I’m gonna try swapping the FICM again, as I swapped it before with ****ed exhaust valves, so kinda throws that diagnosis out, but other than that, I’m stumped…

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DEEZUZ · Dec 24, 2021

Can you infared gun the manifolds?

Can you isolate the issues to 1 bank or both banks.

A ficm splits the engine in half.
1,4,6,7 vs 2,3,5,8

6.0 Tech · Dec 24, 2021

Don’t have infared gun. It seems to be 1 bank, as 1&5 were the misfires. When it first started 1,5,&7 were down, 7 eventually cleaned up. It almost seems like it’s not injecting at the right time. Tried different tune as well. Runs a lot like the egr is hung open. The cooler is plugged, so if it was hung open it wouldn’t be an issue. I’m wondering almost if we got a bad valve job on one of the heads… When I pulled it apart the passenger side of the intake was full of carbon, drivers side was clean

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DEEZUZ · Dec 24, 2021

This truck alone would warrant an infared shop tool purchase.

This truck runs exactly like 1 I did 10 years ago and I had combustion coming up through the glow plug sleeves.

Measure compression manually each cylinder

DEEZUZ · Dec 24, 2021

Just pics of my gun on a clogged then fixed heater core flow

6.0 Tech · Dec 24, 2021

Yeah I guess I should probably get one. Ok, I’ll run a full manual test on it and see what I’ve got Monday. This piece of **** has me so baffled… don’t think there’s been a 6.0 I haven’t really been able to figure out, this one I’m lost on… appreciate it man.

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DEEZUZ · Dec 24, 2021

I can't recall if I told you about that one I fought but I had 20 hours in it and the guy sued us and another shop took it apart and said the glow plug sleeves weren't seated and the customer supplied the heads from a very well known company who didn't back us up one bit..

6.0 Tech · Dec 24, 2021

Nope, didn’t hear about that. That sucks. Makes sense though. However, typically when I e seen glow plug sleeve issues, it pressurizes the coolant, or drinks water. But like I said, I’m throwing logic out the window now…

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ghohouston · Dec 24, 2021

I'd swap in a new ficm harness for shiggles. Not much time involved even if it doesn't fix it.

6.0 Tech · Dec 24, 2021

Hmmm, ok. We’ve got a couple laying around. Won’t take too long. Both harnesses looked on, main harness had damn near every temp sensor pigtail broken, like they typically are. But cam/crank pigtails looked ok, FICM harness looked fine. But I know visual ain’t ****, and didn’t test it. Thanks man!

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79jasper · Dec 24, 2021

ghohouston said:
I'd swap in a new ficm harness for shiggles. Not much time involved even if it doesn't fix it.

Philosophically speaking, shouldn't that show on a buzz test or balance test?
I feel like start there, then do a compression and leak down test.

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6.0 Tech · Dec 25, 2021

79jasper said:
Philosophically speaking, shouldn't that show on a buzz test or balance test?
I feel like start there, then do a compression and leak down test.

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Buzz test passed, didn’t feel the injectors when they buzzed to verify it was the correct ones buzzing. Power balance prior to swapping the injectors showed 1&5 dead, didn’t re run the power balance after swapping the injectors, fired it up and verified it still wouldn’t rev. Don’t remember how it was idling. Had been a long day by that point.

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ghohouston · Dec 25, 2021

79jasper said:
Philosophically speaking, shouldn't that show on a buzz test or balance test?
I feel like start there, then do a compression and leak down test.

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You'd think so, but I've seen so many goofy electrical problems, you never know. Like I said, if it doesn't work, he isn't out a bunch of time.

bismic · Dec 26, 2021

If you have an early FICM (even though it is an 05 or 06 engine), they have their own individual circuits, so you can get individual injectors dropping out with a bad FICM. A bad logic side to a FICM will still pass the buzz test. Do you have a known good FICM to try?

6.0 Tech · Dec 26, 2021

bismic said:
If you have an early FICM (even though it is an 05 or 06 engine), they have their own individual circuits, so you can get individual injectors dropping out with a bad FICM. A bad logic side to a FICM will still pass the buzz test. Do you have a known good FICM to try?

Yeah gonna give one a shot, I swapped FICMs previously, but that was with a **** head on it. So I figure that test got thrown out the window due to the valves being hung open

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6.0 Tech · Mar 22, 2022

So, think the saga has finally ended with this piece of shit… has had me banging my head as hard as I can on the wall every time I’ve had a chance to work on it. So after throwing a used set of heads in it from our race truck, thing still ran the same. Swapped engine harnesses, FICM harnesses, cam and crank sensors, ficms again, pcms again, tried everything. Tan a manual compression test and my bank 1 all 4 cylinders were royally ****ed. Like 50ish psi… pulled the motor again, no cross hatching on bank 1, had several valves that were leaking, motor went from ok to ****ed in about half hour of idling, no idea why. Built another motor with a good core we had sitting on the shelf. Used as many parts off the core as I could. Pistons, cam, crank, new bearings and rings, new set of heads. Dropped it in, ran the same. Got fed up walked a few doors up and talked to a big truck shop. He recommended swapping the hpop as cat engines will do similar when the pump is taking a shit. Never seen an 05 pump fail like that, but **** it. Put the pump in, fired up and revved no issue. I had left a lot of stuff off/loose/half assed assuming it wasn’t gonna work. So buttoned it all up, and no issues aside from an exhaust leak at the egr cooler to up pipe gasket. Fixed that, and then the ****er won’t start… At this point I’m contemplating eating a 12 gauge for lunch… so start going back thru and unbolt the down pipe, still won’t run. Said **** it and pulled the up pipes loose at the manifolds, and **** me if it don’t run… so pulled the turbo off and apart. No issues in it aside from sootier than a chimney. So while it’s getting cleaned I figured I’ll pull the up pipes off, cause at this point why the **** not, to verify there ain’t a bird or something stuck in them. Lo and behold the damn egr scoop on the short rh pipe had come dislodged and was blocking the entire pipe, and with a welded cooler the exhaust had no where to go.

Come to the conclusion this is probably what started this whole fiasco. That thing come loose, back pressure on that side blew the valves open and bent them, then excessive back pressure caused the motor issue after head swap. ****ed up thing is with it being on the rh side ebp wasn’t showing any issues, but for all we know it could’ve been over 200 psi or something…

Sorry for the long post, but figured this weird shit may help someone in the future…

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