At a complete loss

S

Satcheln

New member
Looking for some insight. Made a post last week about some issues I was having, took the truck to a shop and was advised that it was in need of some new injectors. No big deal, 6 new injectors and tubes. Started up and still a rough idle, low on power. Thought I missed something, tore it all back apart to double check my work. Everything is triple checked and torqued to spec. No luck, rail pressure was funky at and idle and while driving, replaced the FCA. No luck. Truck acts like it’s loosing prime, takes 2-3 seconds to fire up, puff of white smoke if engine is cold puff of black smoke if it’s warm. If I unplug the FCA while running rail pressure goes to 12.6k. I’ve been told it’s supposed to max at 26k? Fuel filter is brand new as well. I have ohmed the valve cover harness and nothing seems out of spec there. Also have a plug in the rail to eliminate a relief valve issue. Has anyone ran into this? Im at a loss. Thank you.
 
yea the 12.6k isnt right i believe. Any way to check what commanded rail pressure is? Would also check to see that the lift pump is good to go power wise and flowing enough just to take that out of the equation. Definitely inspect and check power at the FCA connector. I had that thing go bad once (recessed pin) and wow what a pain that was. Im assuming dual cp3's arent in the equation.
 
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I should add that while driving truck makes 26k of rail pressure. No mixture of fluids internally of any type as well. Turbo barks loudly when shifting into 6th if cruising at a low rpm.(68rfe). No blow by as well. Truck has no codes
 
So it runs alright other than the low power when warmed up? No smoke?
We just had a school bus in here with a 6.7 with the same complaint, however; it had emissions codes for regen temps and was derated.
What we found was the intake heater had burned the power contact and sent a piece through the engine. Damaged a valve seat, piston and turbo. If your truck is missing emissions equipment, you won't see the code like the bus, and of course it wouldn't derate. I'm not saying that's what's up with your truck, but your story rang a bell. I'd take a good look at the stud on your intake heater.
 
Truck has a rough idle when warm or cold, very choppy. Truck is fully deleted with AFE intake, 5”exhaust and a smarty jr67
 
Satcheln said:
Truck has a rough idle when warm or cold, very choppy. Truck is fully deleted with AFE intake, 5”exhaust and a smarty jr67
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That's what I figured. So you won't see any codes related there. How about boost ? Exhaust brake ?
 
Boost wise it’ll make 32-36 pds, and exhaust brake works as it should. I originally thought it was a turbo issue but quickly ruled that out. Bearings are nice and tight as well no shaft play
 
Satcheln said:
Boost wise it’ll make 32-36 pds, and exhaust brake works as it should. I originally thought it was a turbo issue but quickly ruled that out. Bearings are nice and tight as well no shaft play
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I assume you check valve adjustment while you were in there ? That's all I got.

I wish I could be more helpful for you. Please let us know what you come up with if you find the issue.
 
Yes sir all valves a set to spec and I found no pushrods while I was in there. I’m always wondering if it’s a stupid sensor tucked away somewhere
 
Just throwing this out there. We’ve had similar problems on a few buses that ended up being a fuel return leak, either in the fuel galley in the head from a connector not seated properly or the line at the back of the head. There’s also a small expansion plug behind the fan support that we’ve had blow out a couple of times.
 
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