Rough at all RPM, sounds almost like a dead miss. Need help BAD

[Dave769]

Anyone have some input on what sounds alot like a "dead miss"? I'm not sure where to start throwing parts. Seems the more I read the more possibilites show themselves. Engine just started running rough suddenly. '04 6.0 w/121k on it. New turbo and EGR valve in '06. New EGR cooler, oil cooler, head gaskets and head bolts in '08. All new injectors in '09, and FICM in '10. Where to now?

[a2elvis]

If its a dead miss at idle pretty much gotta be injectors, wiring to the injectors, or compression. If the miss is intermittent its most likely not compression.

[SixStringMadness]

I had an injector connector that liked to get loose. When it was disconnected, it was immediate rough engine. Check the wiring to the injectors and FICM, and the connectors too.

[Dave769]

Are these injectors that prone to failure? They're only 2 years old and i change my fuel filters at every oil change. Any possibility of something electronic causing a rough running condition?

[SixStringMadness]

Originally Posted by Dave769

Are these injectors that prone to failure? They're only 2 years old and i change my fuel filters at every oil change. Any possibility of something electronic causing a rough running condition?

that's what I was attempting to say in the post above. Check the wiring between the FICM and injector connectors, and of course the connectors

[a2elvis]

Originally Posted by SixStringMadness

that's what I was attempting to say in the post above. Check the wiring between the FICM and injector connectors, and of course the connectors

Yep most likely gonna be a wiring issue... It is possible for the injectors to fail prematurely, most of the time on the oil side of the injector. Alot of guys recommend RevX to try to free up a stuck spool valve.

[fixxxer-upper]

I see everything you have replaced so far, but don't see any components associated with the HPO system. Have you checked the ICP sensor and wire pigtail. ICP failure is common on the early models where it was located under the turbo and subject to high heat. I have had two sensors fail so far. I now carry an extra in the glove box. Late 04 builds relocated the ICP to the right valve cover. You can unplug the ICP which will make the computer go to the default setting for high pressure oil, and your issues may disappear. Doesn't hurt to try. My ICP failures made the truck run like it was "missing".

Pull out the IPR and check the screen for blockage or damage. A blocked screen will prevent the valve from properly regulating the oil pressure to the injectors. I had this issue as well. Have you air pressure tested the HPOP and listened for leaks? I recently completed work on an 04 that lacked power and had intermittent shuddering. The issue was solved by replacing the failing D ring on top of the HPOP which seals inside the cover to maintain pressure to the ICP and IPR.

As you probable already know, recheck the FICM connections, injector connectors, and FICM voltages for main power and logical power.

Overall, not too time consuming, and no additional money spent "throwing parts" at the unknown.

[justinmix]

Everyone had good advice on things to check. I would start with checking codes, if ICP is out of whack or if you do have a dead miss it should have logged codes for it. It won't necessarily always log codes but if you truly have a dead miss it should have.

Does it smoke at all when it's missing? If It's not smoking and seems like it's running on 7 cylinders then it's more then likely an electrical issue, like shorted wiring or something with the injector solenoids.

Where did you get the injectors from? If they were some generic rebuilds then I bet you have an issue with one of them. There are a lot of people that just replace a few parts on injectors and resell them. I see it all the time.

[justa03]

If its a wiring issue on the injector side it should def set a code. Like the others said check your ICP and when its missing if you wanted to you could unplug one injector at a time till you find which cylinder is bad. My HPOP went out on mine and caused only CYL 4 to drop which baffled me but it is what it is. Good luck