Full de-mandate on a 15 litre Cummins

[Fleetman13]

I’m not expecting them to fix it! Ive been a diesel mechanic and have been aware of how aftertreament systems work. The only thing that has been touched by the dealer ship on this truck is recall work which the sticker slapped on the valve cover from the campaign done on this truck a few years back not only consisted of some after treatment parts being replaced but a calibrate done on the ECM as well. Ever since then the truck has been a turd. It used to accelerate up hills towing a school bus behind it now your lucky if it hits 35 at the top of hill. The problem I’m running into is the trouble tree just tells you to fire the parts cannon at the freaking thing and that’s it. I’ve done all I know to do as far as checking the egr/aftertrearment system as much as I can. Although this is our only x15 in the fleet so I’m not extremely familiar with them but I hear everyone on here talk about how finicky they are. I manage fleet shop with 500 assets and they are mainly 6.7 Cummins I know how they work extremely well. As far as the truck being worked on I’ve turned every bolt on it other than warranty or recalls.id like to know more info on the egr tune up you speak about? I also keep the cans blowed and cooked on all of our fleet every two years or if a turbo shits the bed/egr cooler what have you. That I see fit to cook and blow the cans we own the equipment to do that in house in our shop. I’m just at a loss on this x15 cause Cummins won’t give you any info but to pay them to fix it and eff that or fire the parts cannon at this specific fault code. It passed the air handling test passed the deposit burn passed regen analyzer and passed the scr test/nox sensor rationally test I’m open to ideas for sure. I know on our 6.7s if you change a few parameters in the ECM for after treatment the issue cut in half. We see more DEF headers not working correctly than anything now and an occasional turbo fault code for mechanical nozzle not responding which we tear down and clean the turbo cook and blow the DPF and send it out the door not to be seen again for awhile