No Codes! No Lights!

[JimT]

As to the manifold pressure, you'd be looking at about 34-36 psi for the max. Don't be fooled, Insite will report pressures as inHg instead of PSI. conversion is roughly 2 inHg to 1 psi. Maybe you know this, but it catches some people off guard at first (like me) so figured I'd mention it.

Was the DOC replaced along with the DPF? Your symptoms don't point to this as an issue, but it'll be good to know going forward. Also, it's usually recommended to replace the DOC and DPF as a pair. Depending on the abuse history, 400,000-600,000 is the average life for a DOC/DPF pair.


So, I don't know what these different Tier 1,2,3,4,etc.. actually mean other than they are charging you more and more money. Get yourself an Inline 6 reader and a copy of Insite with any old laptop (all it needs is Windows XP or 7, 10 might work, and a usb connection). $300ish on e b ay and register for a free Cummins Quickserve Online account, then you'll have no use for Tier anything. Never assume any mechanic has done something unless they explicitly say so and even then you can't be 100% sure unless you actually witnessed it. Also, poke around more on this forum for more info on EGR, DPF, SCR and Aftertreatment. There is no "halfway" mode as you keep mentioning. There is Passive Regen, Active Regen and Forced/Parked/Manual Regen (The only real difference between a Parked Regen and a Forced Regen is that the Parked Regen uses a dash switch to "request" a regen, while the Forced Regen is done through software such as Insite and will attempt to run even if some faults are present).

If research isn't enough to figure out which mode is running then you can easily hook up your laptop with Insite running Data Monitor and drive down the road. While the event occurs check the data, it will clearly tell you what mode the Aftertreatment system is operating in. Like I mentioned earlier, your description sounds like it could be running in SCR warmup mode, which would be clearly displayed within Insite. Regardless, knowing the value of this parameter during the event will clarify exactly what's happening and point to the next step(s).


I can't stress the importance of that last bit enough. Without knowing exactly what is happening then you, and the rest of us, are just making blind guesses.


As Rawze mentioned earlier, it's also possible that the aftertreatment system is functioning properly and the engine is just producing excessive soot. Have you tried disconnecting the exhaust from the back of the turbo to see what is actually flowing out? You could also be burning excessive oil and/or coolant which will clog up the DPF with ash. I'm not saying that's your problem, just listing possibilities. These systems are sensitive and depend on each component to function properly otherwise the entire system is thrown off. Since you said components from the old engine were used on the current engine then it's possible that one of them is a factor.

Don't remember if this was mentioned anywhere, but a complete EGR Tuneup is always a good place to start when trying to diagnose aftertreatment related issues. Also recommended to be done on a regular basis to PREVENT common problems. This includes replacing sensors as well as physically cleaning soot buildup from sensitive components, to inspecting parts for leaks and proper functionality.

The users of this site will try to help others whenever possible, however (and i could be wrong here, but...) the main purpose of this site is to help individuals to educate and help themselves. That's where you need to be now. Educate yourself on HOW these systems actually function then stop running to shops who only want to take your money. Take control of the entire process yourself. Some basic tools, knowledge and Insite/quickserve is all you need to methodically diagnose and fix most things on these engines. Don't let your pre-emissions knowledge fool you. MANY aspects of modern engine operation have been affected due to emissions compliance. Not trying to bash your knowledge or experience, but almost every aspect of the modern engine's operation is in some way modified for emissions reasons (sometimes via ECM programming that 99.9999% of people, including the anointed Cummins techs, are completely unaware of).