C15 Camshaft problems?

Will try turning the engine fan trick, but the stumble while sitting is momentary, to duplicate it, we had to drop back to idle, then slowly rev to approx 1000 rpm; however bobtailing down the road, at steady speed, the stumble happens approx every 30 seconds- traveling = more of a load maybe?

Only put about 20 mi since cam swap, all bobtail, and overpass cloest thing to a hill in our area (so LA), and only traveled it once, didn't pay attention to performance.

Due to my lack of knowledge about the workings of the fuel system, not understanding your comment about the fuel leaving the injector tip, but will print this & show to tech.

Thanks for your input!

 

Hello sleepless nights,
Interesting point, if I read correctly, you installed 6NZ injectors in your MBN at the time of your cam swap? Was your ECM already changed over to the 6NZ? I remember your comment about the exhaust rockers, but did you have any other problems, such as the stumble/white smoke thing?

 

Thanks again for the suggestions, DDS, and fairly sure the fuel pressure, and air in system was not checked; I wasn't there the whole time, but will ask the tech.

Concerning the 550/1850 flash, this was done by a fellow with a laptop, while he was sitting in his car, plugged into my truck.
While in Illinois, unknown to me, the little wastegate hose beneath the turbo had split almost in two, causing power derate, and the check engine light to stay on, (#25 code, something about the boost sensor) IIRC. I stopped at a truckstop, where a local gave me a number to call. This fellow happened to be about a 1/2 mile from me, came over, hooked up, found the problem, then offered to do the 550 flash, take it off of soft cruise, etc. I asked about flashing to a 6NZ, and he replied that his uncle (who was a former Cat tech) had not yet trained him to do that, and he thought that it would require going to their shop, and couple of hours work, by the uncle. He did tell me however, that it was a full 550 HP/1850 flash when I asked if this would also raise the torque rating to 1850.
Is it possible that this cam will not work with a MBN ECM, and the basis for all my grief at this time?

 

Based on what I posted earlier, do you think that this fellow could have flashed my ecm to a 6nz? Once he hooked his laptop to my truck, he referred back to a notebook, then made changes, but honestly couldn't tell me if it would change my ecm over to a 6nz. He stated that his uncle also did something to ecms at their shop, that took a little more time, but didn't know exactly what. He was more of the road service guy, while his uncle stayed in the shop.
Whenever he offered to do the uprate, I had mentioned that this was a "bridge engine" to which he replied that it was an MBN and he had put that flash in a lot of the local trucks, and that I would be very happy with the results.
I had read that to change to a 6nz ecm, you would have to "replumb the wastegate," which I had not done, assuming the ecm was still an mbn.

He also offered that if I were in the area, to call, and he would hook back up if I wanted, just to check the fuel mileage, etc. Three monthes later, I WAS passing through, stopped, and he did hook up showing an improvement in fuel mileage. I again asked, if he had done a 475 HP/1850 flash, and before I finished talking, he replied that it was a full 550/1850 flash.
After the flash, power gain was considerable, and fuel economy went from 4.86 to 5.3 at the ecm.
In all fairness, I purchased the truck used, and previous owner pulled reefers, I pull tanks, flash was done 8 months after purchase, 19K mi later is when he rehooked to ecm to check fuel mileage.

 

What you say may be true, if you read my previous post, replying to DDS, the young fellow that flashed my ecm knew how to install it, but didn't know much else, and I knew even less!

My fuel mileage has improved considerable, but many factors come into play here; previous owner pulling reefers, I pull smooth side tanks, shortly after I purchased the truck, the fuel temp sensor went out, throwing a derate code which took some time to remove, then shortly after that, is when the small wastegate hose under the turbo split, another code, another derate. Prior to this cam fiasco, truck has settled down to a consistant 5.8-6.3 mpg (hand checking). I feel it should do better, given the trailers we pull, and the fact we are NEVER allowed to exceed 80K gross. 13 sp. 3.36 on 24.5 normal height rubber, the truck is long legged, which should help.