Help! Cummins Isx CM871 Programming

[mxmom777]

Absolutely, not trying to troll anything.. Just trying my best to come to an answer that nobody is able to thus far.. the truck has not been working since mid Dec, he's been taking it to shop after shop and its now close to $20G and absolutely no further ahead. I do have a background in CNC Machining so know enough to realize we are changing sensor upon sensor not even relative to any part we've been advised was the cause. Also, when the engine acts up cycling the key off and eventually back on seems to give it a fresh start. It started to be a noticeable issue when it began dropping below 0 Celsius. He just purchased this truck mid May 2022..

The truck will run fine for 2-3 hours into the trip then fall flat on its face. and run roughwhat he relates to be like a freight train. Then it will do it's thing and resolve or he's pulled off and seems to do a key cycle getting fuel, unloading ect and then its good again for 2-3 hours.

The cummins cert shop ended up doing a regen but said it took a very long time. They argued the program you advised of was wrong and would blow the truck up and not the correct one. They concluded the engine was worn out and needed an in-frame. So my husband told them to give him a quote (he failed to consider the tech that suggested this is the brother of the owner of his usual repair shop and it was suggested to him in conversation a couple of weeks ago that the brother does engines as a side job), I might be way off and reading into it too far but what a coincidence... He failed to tell them the truck has around 300,000km since a head/block and complete overhaul was done by Kenworth.

- so after this shi#t show I provided the TSB for the Update and they completed it this morning. I asked if it regened and they advised - They put the calibration in and did the regen analyzer test and it came up failed due to Diesel Particulate Intake Temp being to low.

I asked them if they happened to look at the OEM ambient sensor as I noticed that it was a constant 72F every time it was connected to the computer anytime it had previously connected to the computer prior to this update. They told me they didn't check it and that they wouldn't be able to get it in to do until end of week at best. - So not sure if still 72F IF SO WHY WOULD THIS HAPPEN? SEEMS LIKE ITS DEFAULTED TO ROOM TEMP. I am in Ontario Canada so feel this would play a significant role.

It was at cummins a couple weeks ago, they said could be DOC but then turbo. We asked for readings to conclude turbo replacement and they could not provide so he took to original garage they had been doing the work at and asked them to confirm turbo. They stated everything was operating as it should and this is what was concluded. -exhaust temps did not get up past 500, but turbo speed seems to be in spec. Regen analyzer failed. DPF intake temp is low.
- removed exhaust backpressure sensor, cleaned soot that was in sensor and pipe from manifold. cleaned and inspected manifold and sensors.
- split turbo to check veins. no seizing or sticking so cleaned and reassembled.
ran regen analyzer again. exhasut temps did come up past 500 degrees and doser began to inject. Found that once engine fan kicks on when coolant temp is 210 degrees, it drops back down to 200. Exhasut gas temps drop and dosing stops. Exhaust temps can't climb back up enough to dose fuel before engine fan kicks back on causing regen to abort.
- replaced coolant temp sensor and replaced harness plug for sensor. did regen analyzer monitored temps began dosing fuel but exhaust temps wont stay up...