Regen Problem

Which engine make, model and year would help..........

 

Could still be a number of issues. First of all, when you clean a dpf, you also need to clean the DOC. The DOC is the section right before the dpf and mostly responsible for creating the high temperatures required to burn off the collected soot. If the DPF is ok, the doser ok, but the DOC is partially plugged, your regen will never work. Also, unfortunately, not all DPFs that go through the cleaning service are actually cleaned. It depends on who does it and what machine and procedure they use based on the current condition of the DPF. When it goes through a cleaning procedure the air flow rate through the DPF is measured. By this value they can tell the condition of the DPF. Did you get any of this information? Did you have the DOC cleaned? I am not familiar with Detroit systems, so I cannot explain the running rough. There may be more going on with mass air flow, egr and DPF sensors that commonly get carbon plugged after time and throw off everything.

 

This is helpful to me - thanks. (I'll add it to the list of "things the guys I actually PAY should have told me") !!

 

The throttle valve is used for a variety of engine performance and emission related tasks, but it is mainly used to partially block off intake air when doing a parked regen. The choked off intake air helps increase exhaust temps which is required for a proper regen. The DOC is the "Diesel Oxidation Catalyst". This is the section right before the DPF. The DOC is like a catalytic converter found on a car. It contains a precious metal coated honey comb that the hot exhaust gases pass over. The engine will inject extra fuel into the exhaust stream. Then the excess fuel hits the DOC material it will basically burn to a temp of about 1100 degrees. This super heated exhaust gas now goes into the DPF to burn up the collected soot. When the DOC is plugged or the coating is wearing away you will get a "lazy" regen. The temps out of the DOC will be lower than 1100 or so, typically about 800. The burn is only partially happening, and therefore, the soot in the DPF isn't fully burned down. This results in frequent regens. They need to be looking at the aftertreatment temps to see where the temp loss is, if any and go from there.

 

I may be having the same problem. I started yet another parked regen and then went into Home Depot and bought an infrared thermometer. After 40 minutes I checked the surface temp of the DOC and DPF. Highest temp I got was 290, WTF!! I then checked the exhaust manifold temp, 700. So the thermometer is working. I am not getting the high temp I need for a proper regen.