6nz Cat C15 injector problem

sounds like you have a cut oring or two floyed my other truck that i have a driver on did the same thing lower orings where cracked i put new orings in and it's as good as new

 

my 2003 CAT C-15 6NZ IN 2003 Pete 379 is driving me nuts. Under load it pops, stumbles and runs rough. minutes later all is well but its short lived (5 minutes). CAT did a platinum rebuild on it 2 years ago, with 4 year warranty , but even they are stumped. CAT put 2 new injectors in it and 4 exhaust manifolds because the gaskets and / or slip joints keep blowing out. Exhaust system not plugged (tore it completely down to check). I put all new fuel lines right from the new pump to both tanks. Washed out both tanks, checked fuel suction tubes in tanks for cracking, new divertor valve, new divider valve, new fuel pressure regulator, new primary fuel filter housing, new primer pump, then a complete delete of primer pump, opened up fuel flow to head and opened up return fuel to tanks. Fuel @ 105 psi under load, 85 psi @ idle. New engine wiring harness, new injector wiring harness, new cam sensor, crank sensor, air intake sensor, fuel temp sensor, throttle position sensor, atmospheric sensor. Even installed a "Air Dog" fuel air seperator system.
A new speed sensor, speed sensor wiring and the list goes on.
Bottom gears (from a stand still) and no problems at all. Problem starts as soon as boost hangs high for longer than 4-6 seconds (when truck is pulling and it takes 4-6 seconds between shifting) and engine begins the popping / stumbling. Keep the boost low and my problem stays low.
High boost means high fuel demand, high air flow, high torque, longer time the injectors stay open to acquire adequate fuel for injection. Im well over $20,000 into trying to rectify this problem but im totally stumped. The only items left to change is 4 more injectors and the ECM, and if someone with knowledge of such a problem would say "Change your ECM and your problem will be solved" i would do it in a heart beat. But here in Ontario Canada, a new ECM for a 6NZ is over $5,000 !!! Thats a costly gamble without the guarantee that a new ECM will fix it. Injectors are also high dollar, $985 / each. I spoke to CAT MAN on "Just Answers", but he could only recomend doing what i have already done.
DOES ANYBODY HAVE ANY IDEAS....PLEASE.
Im just a 54 year old family man with a disabled child trying to pay the bills , and get through from one day to the next. PLEASE FEEL FREE TO TEXT ME WITH ANY HELP AT ALL YOU MAY BE ABLE TO OFFER, I WOULD BE VERY GRATEFUL.
Thank you very much.
905-746-5505

 

could be the ecm wires truck side

 

Do your injector o-rings look good? Especially the bottom fuel o-ring. If your injector seats in the head, are warped, it allows combustion to get up to the fuel o-rings, and after they deteriorate enough, pumps combustion into the fuel under heavy load.

 

Is it an intermittent misfire under load?

 

thanks for talking with me on the phone good sir. still chasing this issue and hope to get it resolved. if anyone has any real solution for this missing problem that worked for them please post action taken and results. sounds like there's more than a few of us experiencing this problem with their high mileage 6NZ engines.

Troy
if you don't want to sign up and are reading as a guest like I was, feel free to call me.
780-618-6649
Alberta Canada.

 

I

 

I have repaired many like this. Machined the injector seats.

 

You talk in about the hole it’s self ?

 

The seat in the head where the injector seats.