How to Actually Diagnose Aftertreatment problems?

I've got a 2011 volvo vnl in derate. Message says "analyzing def quality 5mph derate removed". It's my understanding that anything that could cause high outlet nox could cause this? So if I change the def and clean the dpf filter and it's still got the message it's going to need a scr?

Also as a side note I've attempted forced regen and dpf temps are only around 700 degrees. But also the duty cycle on the 7th injector is very low 7% or so. I would think the ecu would command more duty cycle out of the 7th injector to get it up to temp. The dpf soot ratio is 58% so maybe it does that because it doesn't really need a regen?

Any help appreciated

 

Here is some more info if that is helpful on the regen, looked like it was only around 3 psi during. Wondered if that is normal for the d13? Assuming the temp needs to be higher that for a successful regen?

 

haha not the advice I was hoping for but you might be right.

 

Hmm yeah I did take 7th injector out and tried to clean it with ultrasonic cleaner didn't seem like it was spraying like a normal injector would. Probably should just replace it. When I was checking the def doser I did change the gaskets of the flex pipe between dpf and scr (bellows) and still got those temps.

Doesn't seem to have any obvious boost leaks but should check that if it that far off. Turbo didn't seem to have much shaft play so I figured it was ok but maybe the turbo actuator could be failing? Its has only been running 25psi max loaded but I thought that was because of the derate.

I still don't understand why the 7th injector is not commanding more duty cycle though. Makes me wonder why the ecu not command 100% duty cycle on the 7th injector if it needs more heat. Almost seems like possibly a software problem potentially too not sure if a ecu update would fix mine. But I've read in another thread an update fixed theirs but they had a slightly different problem than me.

Also does anyone know if PTT 2.8 can exit inducement (derate) on my generation of Volvo let me know. PTT 1.12 can't I don't think

 

Sounds good-Also does anyone know what ppm nox outlet should be idling- or pulling a load? Like at what ppm would a derate happen if anyone knows