CAT C15 /6NZ trouble continues

truck 307 · Nov 18, 2019

Feel free to call me

idahoheavyhaul said: ↑

Need your help!!!! Please contact me, my business is in jeopardy. I bought the truck from hell and it seems I might have bought a new cat head from hell also. 208-800-8661
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Feel free to call text or email me.
My number is 905 746 5505.
Always happy to help
-Dan

W903B · Jun 24, 2020

truck 307 said: ↑

Thanks for your support. No welding was done at all, as i confirmed visually myself and thought of when it all started , which was the first day, the first load i pulled, about 18 months ago now. What a journey its been. But thanks to guys like you with still some caring and wish and want to help, i think im getting close to the end of the problem.
As im typing this, i was thinking. Although the previous owner said "NO" when i asked if he ran a Bully Dog or any other such tuning device, theres 2 velcro spots overhead of the drivers seat, one with power wires to it. The stereo already has/came with, satelite radio. The spot where his GPS was mounted is very clear, and on the ECM is a (approx) 12 gage wire coming out of it, about 8" long, with a female type butt connector on it. CAT guessed, saying "its probably a power supply of some sort" as they held the hood about to close it one day. But now im wondering if he (the prior owner) tapped into it with a engine power booster of sorts, like a "Bully Dog" or similar, and now the ECM is (the best i can say) "confused" ?
Well, i will put it before Greg this coming Monday, along with the other info so many guys have been helping me with.
Thanks again
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Bully dog tuner doesnot need any wiring , it is connected to post 9pin or 6 pin

jondandy · Sep 3, 2020

truck 307 said: ↑

Ok guys, it's over...finally.
Wanted to be 200% sure before I said that.
Here's what it was and how I found it.
As followers of this thread know, for 2+ years I did it all, CAT did also, 99% CAT did was warranty under my Platinum warranty plan.
After CAT and everyone else poked at the bear, I always continued on my own, changing every sensor, every wiring harness, fuel pump, fuel supply line, you name it, even pulled the tranny, as it was always in upper gear pulls that the engine? stumbled shook and lost power as a result.
One day a month ago , staring out the windshield, I started to think I messed up on a stratoflex fitting when building a fuel supply line, thinking I forgot to live the hose before threading on the tapered section and I cut a flap inside the hose. So , easy enough, I re connected the old supply line.
No change.
One day, a few weeks later looking at that capped off new supply line, I thought just maybe I'll try connecting that newly built fuel line to the return side. So, because the return line is normally a size smaller, I bought $110 in adapter fittings. I crawled under the truck, connected the new stratoflex fuel return line, and Monday came around.
I fired up my 6NZ and in 5 minutes I knew I had fixed it.
No stumble
No shaking
No power drop off.
I pulled out the old return line 6 days later, cut it open, inch by inch, until I found it.
Years of hot fuel returning had degraded the rubber, a flap hung down inside the hose half way between the engine and diverter valve.
The way I figure, the fuel temp sensor , before the head , told the ECM, my fuel temp inbound was ??? Let's say 100 degrees. But nope, the return line flap restriction had that fuel much hotter, maybe near boiling.
The ECM wss regulating fuel injection via the temperature sensor, but it was wrong info, thanks to the fuel return line restriction.
Smooooth. Unbelievable smooth running.
Can't thank y'all enough.
Its been a trip guys, and a expensive one at that..
Great thanks to Swaan, engine machinist, and the so many others who stood by my side, ready, willing and dedicated.
Hope I can return the favor one day.
I'll be around, looking, hoping to help another owner op or just anyone in need.
God bless, my friends.
Again, great thanks.
( and, thinking about what one of y'all said many pages back..
☆☆ and that's the last episode, the final season, you were all waiting for on this Netflix series that seemed to go on forever ..
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My '03 6nz stumbles for a couple minutes after a good pull, but only after I let off accelerator to shift up, then it's like an injector is stuck closed? But Cat and other diesel shops could not find the problem, was your stumble issues simular? Maybe I should replace fuel lines too!

Troy_ · Sep 3, 2020

jondandy said: ↑

My '03 6nz stumbles for a couple minutes after a good pull, but only after I let off accelerator to shift up, then it's like an injector is stuck closed? But Cat and other diesel shops could not find the problem, was your stumble issues simular? Maybe I should replace fuel lines too!
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exactly what mine was doing. it was injector seats not properly machined on the factory reman head. replaced head and injectors. @Truck engine machinist has the cure.

Truck engine machinist · Sep 3, 2020

Troy_ said: ↑

exactly what mine was doing. it was injector seats not properly machined on the factory reman head. replaced head and injectors. @Truck engine machinist has the cure.
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I've repaired many, with just those symptoms.

Troy_ · Sep 3, 2020

Truck engine machinist said: ↑

I've repaired many, with just those symptoms.
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if Cat wouldn't have stepped up and warrantied my engine, you would have had an all expenses paid round trip to northern Alberta, Canada.

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