CAT C15 /6NZ trouble continues

Thank you very very much pushbroom

 

Update;
CAT pulled head ( warranty) due to a mild head gasket leak. They sent head out to be rebuilt and I was sure they machined injector seats.
They put 2 cylinder packs in and new bottom end etc bearings ( they weren't busy and I took 2 weeks vacation, so they milked the warranty )
After all that...my problem continues.
In a nut shell ( since it's been a while)
-Engine runs great, no symptoms at all in bottom gears. Once I close in on 16th it starts. 17th power drops and chugging, popping starts. 18th gear can barely pull a empty trailer with my 550 HP 6NZ CAT.
In summer temps my coolant temp climbs fast in 17th or 18th gear and power is hugely reduced.
After running an hour I stop, turn key off and wait 2+ minutes. Start and go and problems are gone for a few hours.
I'm thinking corrupt data in my ECM.
CAT already tried a new ECM but transferred my files onto it.
All sensors and engine and injector harnesses replaced. Sight glasses both before and after the head show zero air in fuel. New fuel pressure regulator, throttle position sensor, replaced.
New power wire ( from battery) to ECM .
New fuel supply lines, tanks removed and checked for cracking in suction tube at top. Exhaust checked for blockages, fuel pump replaced. Fuel at 100 psi on pulling. Boost at 32 to 35 on pull.
Never any issues until prolonged pulling in higher gears.
It all started when I first drove the truck after I bought it ( I drove it like I stole it before signing over the money to the seller)
I bought it. The owner selling it took it to the shop to have a wet line installed. Right fuel tank removed, sent out to be cut and split for hydraulic oil reservoir in 80% of tank. Fuel still on 20% of tank.
Full service was done also.
Soon as I picked it up and hooked to very first trailer the problem was there, and violently bad at first ( first year) but slowly seems to have diminished somewhat, but still quite bad.
I've considered hydraulic oil bleed over from split walled tank but analysis shows zero fuel contamination.
Tank venting, taps etc also checked.
I once ran along my step etc, a fuel line I made up of stratoflex hose directly from drivers side fuel tank to primary fuel filter housing. No change.
Intercooler has zero leaks.
Perhaps ( besides ECM data being possibly corrupt) the torque of the engine is pulling on a wire ON the OEM side of my ECM...
I'm really stumped. As is CAT.
I've written out in big letters..
"REWARD TO ANYONE WHO CAN SOLVE MY CAT ENGINE PROBLEM. $1000.00"
I gave it to CAT and left a copy in the CAT lunch room.
No takers by anyone, so far.
And I mean what I offer.
I want this over with...
Text me if you can help.
905 746 5505
-Great thanks.
Regards.

 

Truck engine machinist, thanks for your reply.
I had mentioned that I was sure that the CAT machine shop did in fact cut the injector seats. The machine shop that does all the work for CAT is who I called and didn't ask if they cut the seats, I asked " so what did you all do to my 6NZ head", and it wss the 3rd thing he told me was done, as he read from the work order. But he also said ( after I asked was there any carbon burns from blow by on the seats). " No. Not at all, but it's part of CATs protocol with all their head's "
I then played stupid. After all done I asked shop Forman at CAT " so what was all done to my engine". Injector seats machined " was on his long list.
Engine pulls strong without issue in all lower gears ( gross weight minimum 136,000 Lbs but usually at 139,000 to 140,000 Lbs every load )
Few months ago, CAT changed all 6 injectors. But first installed one sight glass before the head and one after the head. I drove. Tech in passenger seat with district vice president of CAT sitting in bunk watching CAT program plugged into truck. No air anywhere. No electronic glitches etc yet popping stumbling and violently shaking with power drop in upper gears very noticeable.
She'll pull 146,000 up a hugely steep incline in 12th gear with zero issue's.
But can't pull a empty trailer on flat ground in 17th gear without temp climbing rapidly and incredible stumbling , chugging and popping with massive power loss.
And nobody can figure out why at CAT.
I still say gear programming improperly input or data corruption.
But I'm only guessing.
I need help and am willing to pay.
Any thoughts, anybody, call or text me
905 746 5505
Thanks kindly.

 

Test after test shows no air in fuel system. Sight glasses both before and after the head and we drove and drove for 2 hours, zero air.
But I'll never rule it out completely until my problem is solved.
One tech who heard about my issue ( CAT tech) with a grin as if to say "It can't be that bad" drove with me. "Holly ####" he said repeatedly. "Unbelievable " was next.
It's almost like fuel starved. And I wonder if my now short right side fuel tank ( split as mentioned for hydraulic oil reservoir in part) with fuel supply and return closer together ( 8" + -) is causing it. But then I think no, I ran a fuel line I made directly from top of drivers side fuel tank to primary fuel filter housing , with no change.
Your support is appreciated.
Thanks again

 

The strange thing is that if I shut the truck off after stumbling along for an hour or more in the morning I can actually get some good driving after that without any issues at all.
I don't work weekends but if I go out and start the truck and let it run for a couple of minutes and shut it off and do that again sometime during the weekend ,come Monday the truck runs good for almost half a day