I joined a forum for the Ram 1500 diesels. There's talk there of there still being DPF's on these trucks that regen occasionally as well as the SCR system. My understanding has been that it's either a DPF system or an SCR system, not a combination. Can someone clue me in?

They are both used together for polution control. Here is a website that explains it a little better and has a video that shows the basics: http://www.demanddetroit.com/performance/emissions.aspx

If it has DEF it has a DPF as well. With the DEF SCR system the exhaust goes something like this: DOC-->DPF-->Decomposition chamber--->SCR catalyst

DOC = Diesel Oxidation Catalyst

DPF = Diesel Particulate Filter

Decomposition chamber is where the DEF is injected

and the SCR catalyst is where a reaction occurs with the DEF infused exhaust gasses to turn them into nitrogen and water vapor.

 

Some systems(like on a ISX) also have a dosing injector to inject fuel right into the exhaust before the DOC for running active regenerations.

 

I have a video explaining this all somewhere, I'll add it to this post when I find it.

 

Here's the video I was talking about. 

Edited January 18, 201510 yr by bjytech