ISB 6.7 Too Much Soot Guidance

[DVT873]

(01-12-2021 )Craig Wrote:  Thanks so much for you input, I will have to take your response back and try and get the answers. Sounds like it's going to be expensive, however, they just bought a new truck and I think you may have saved it from the same fate as this one. I'm going up there this weekend so I'll get some answers and try to create a game plan to go through all the systems you mentioned. Or, after reading your response, he may just want to demandate it because of cost. I'm trying to get him to fix it for obvious reasons, yearly inspections and such but didn't really know where to start but now I think we have a jumping off point for sure, can't thank you guys enough :).

Have you run it down the road with the cans off to see if it is making smoke? Twice I have had units make noticeable smoke, especially on acceleration. Clean out the EGRDP ports, one needed drilled and the smoke stops. The EGR DP sensor ports are tough to get clean. They can fool you because of the way the passages are drilled.
Cummins bulletin 5579934 covers that although the pics aren't the best. I don't trust EGR valves to report their position correctly. Replace it. There is a DPF Regeneration Stay Warm feature that can be turned on. See TSB 170058, note that is not available before 2010.
Minimum regen set speed is often at 25mph or higher. This can be set to 5 or 0 if the program allows it. Avoid idle whenever possible or set the RPM up to 900-1000.
All of the above is mainly directed at school buses but helps any stop and go application. Extended idle on these will carbon pack the rings. Most if not all ISB's do not have a 7th injector. They dose fuel into the cylinder on the exhaust stroke. If the regen system is out of wack this can lead to cylinder wash down. An oil sample will show % of fuel dilution. I like how NAPA reports the dilution. Anything above 5% indicates a problem. Ideally 1 or 2%.
Follow up all of the above with EGR tuneup and replacement of sensors and EGR valve.