DPF and DEF

so I'm trying to ascertain if DEF injection is a part of a DPF regeneration, or something completely different and not related in any way..

the way I see it, the DPF regeneration is based on soot load or differential pressure of the DPF filter..

what I assume happens with DEF, is if the NOX sensors see high levels of NOX, DEF is injected into the SCR's to help lower the levels, and gives the bleach smell to the exhaust..

somebody told me the other day that DEF is injected after a regeneration of the DPF to help eliminate the ash that gets into the SCR's which I question..

so what is it?

do the two go hand in hand? or completely separate functions..

Bernie

Completely unrelated. The exhaust goes through the DPF first. The DEF is injected into the exhaust stream later. The only possible connection might be a slightly different DEF usage during a regen due to a slightly different exhaust chemistry during that time.

It would be interesting to know the whole process of the regeneration and where each of the different parts of the process happen. Probably searchable on youtube..

I haven't looked through this in awhile. See if there's something in here that will satisfy your curiosity.

Jbernielh said:

so I'm trying to ascertain if DEF injection is a part of a DPF regeneration, or something completely different and not related in any way..

the way I see it, the DPF regeneration is based on soot load or differential pressure of the DPF filter..

what I assume happens with DEF, is if the NOX sensors see high levels of NOX, DEF is injected into the SCR's to help lower the levels, and gives the bleach smell to the exhaust..

somebody told me the other day that DEF is injected after a regeneration of the DPF to help eliminate the ash that gets into the SCR's which I question..

so what is it?

do the two go hand in hand? or completely separate functions..

Click to expand...

You may be getting this confused with some systems employing true passive regeneration that inject a catalyst to help the soot oxidize at a lower temperature in the DPF, but the Sprinter does not do this.

SSMaui said:

I haven't looked through this in awhile. See if there's something in here that will satisfy your curiosity.

Click to expand...

Thank you!