Regeneration of the Diesel Particulate Filter (DPF)
Here's some basic information concerning the self cleaning (regeneration) of the Diesel Particulate Filter:
Active = fuel is injected into the exhaust stroke strictly for the purpose of increasing exhaust gas temperatures (EGT's) in order to get to the temperature necessary to burn the soot out of the diesel particulate filter (DPF).
Your truck will regenerate (active) when the DPF soot level reaches 65%. This will likely occur every 100-300 miles. You will only see the notice on the EVIC if the soot level reaches 80-90% due to uncompleted regens.
Active self-regeneration occurs when there is not sufficient heat in the exhaust to convert all the carbon being collected in the DPF. Exhaust temperatures are raised by injecting a small amount of fuel upstream of the Diesel Particulate Filter.
The resulting chemical reaction over the DOC raises exhaust gas temperatures high enough to oxidize the carbon from the filter. This is all done without any operator intervention.
Passive = the engine is working hard enough under its own power that the EGT's are hot enough to keep the regeneration of the DPF in process, there is no extra fuel burned as it is not necessary.
Based on my observations, you will not see EGT’s hot enough for passive regeneration at unloaded highway speeds. The EGT’s are actually quite low when cruising on the highway unless you are towing a heavy load, are carrying a full payload, or driving hard.
From forum member Patty:
The truck's programming will make many repeated attempts to regenerate the DPF, from a high soot mass level of 65% down to <10% when a cycle is complete. If your trip is too short and the engine is then shut off, or the truck is put in park with the engine idling, an active regeneration process stops (at whatever soot level the DPF is at). The next drive cycle when the DPF again reaches 65% soot mass the whole process starts all over again. If you are going on a road trip the complete cycle will happen many times over... up to 65%... regen... down to <10%... over and over again.
The following information from the Owners Manual:
EVIC Messages
Your vehicle has the ability to alert you to additional maintenance required on your vehicle or engine. Refer to the following messages that may be displayed on your Electronic Vehicle Information Center (EVIC):
• Exhaust Filter XX% Full Safely Drive at Highway Speeds to Remedy — This message will be displayed on the Electronic Vehicle Information Center (EVIC) if the exhaust particulate filter reaches 80% of its maximum storage capacity. Under conditions of exclusive
short duration and low speed driving cycles, your diesel engine and exhaust after-treatment system may never reach the conditions required to cleanse the filter to remove the trapped PM. If this occurs, the “Exhaust Filter XX% Full Safely Drive at Highway Speeds to Remedy” message will be displayed in the EVIC. If this message is displayed, you will hear one chime to assist in alerting you of this condition.
By simply driving your vehicle at highway speeds for up to 20 minutes, you can remedy the condition in the particulate filter system and allow your diesel engine and exhaust after-treatment system to cleanse the filter to remove the trapped PM and restore the system to
normal operating condition.
• Exhaust System — Regeneration In Process Exhaust
Filter XX% Full — This message indicates that the Diesel Particulate Filter (DPF) is self-cleaning. Maintain your current driving condition until regeneration is completed.
• Exhaust System — Regeneration Completed — This message indicates that the Diesel Particulate Filter (DPF) self-cleaning is completed. If this message is displayed, you will hear one chime to assist in alerting you of this condition.
• Exhaust Service Required — See Dealer Now — This messages indicates regeneration has been disabled due to a system malfunction. At this point the engine Powertrain Control Module (PCM) will register a fault code, the instrument panel will display a MIL light.
• Exhaust Filter Full — Power Reduced See Dealer — This message indicates the PCM has derated the engine to limit the likelihood of permanent damage to the after-treatment system. If this condition is not corrected and a dealer service is not performed, extensive
exhaust after-treatment damage can occur. To correct this condition it will be necessary to have your vehicle serviced by your local authorized dealer.
CAUTION!
See your authorized dealer, as damage to the exhaust system could occur soon with continued operation.
Soot Loading Strategy (Quoted from Forum Sponsor GDE)
The ECU runs two different strategies in parallel and takes the higher of the two outputs to determine the current soot loading:
Strategy 1 is a simulated value, and is calculated according to how complete the previous regeneration was, and how the engine/vehicle has been operating since then (engine speed, load, ambient conditions, exhaust temps, etc). Different OEMs design different variations of such a strategy, but for the most part the high level concepts are similar. The strategy employed by the Ram's stock tune is fairly rudimentary.
Strategy 2 is a physically measured value calculated off of measured pressure drop across the DPF, the DPF temperature, and the known flow rate of exhaust gasses.
The soot loading is used to trigger the regeneration when all the correct criteria are met.
Just as a note for some more info...
Passive regens happen when there is sufficient exhaust temperature and a favorable NO2/NOx ratio for the soot to burn. This phenomena will happen starting with exhaust temps in the 380-400°C range.
However... the stock tunes are not capable to detect that passive regeneration is taking place, and to thus slow the modeled accumulation of soot and/or decrease it if the burn rate exceeds the production rate. This is why the intervals are not improved more in the highway cycles.
...we fixed this with our tunes, in order to avoid regenerating when it's not necessary.
Here's some basic information concerning the self cleaning (regeneration) of the Diesel Particulate Filter:
Active = fuel is injected into the exhaust stroke strictly for the purpose of increasing exhaust gas temperatures (EGT's) in order to get to the temperature necessary to burn the soot out of the diesel particulate filter (DPF).
Your truck will regenerate (active) when the DPF soot level reaches 65%. This will likely occur every 100-300 miles. You will only see the notice on the EVIC if the soot level reaches 80-90% due to uncompleted regens.
Active self-regeneration occurs when there is not sufficient heat in the exhaust to convert all the carbon being collected in the DPF. Exhaust temperatures are raised by injecting a small amount of fuel upstream of the Diesel Particulate Filter.
The resulting chemical reaction over the DOC raises exhaust gas temperatures high enough to oxidize the carbon from the filter. This is all done without any operator intervention.
Passive = the engine is working hard enough under its own power that the EGT's are hot enough to keep the regeneration of the DPF in process, there is no extra fuel burned as it is not necessary.
Based on my observations, you will not see EGT’s hot enough for passive regeneration at unloaded highway speeds. The EGT’s are actually quite low when cruising on the highway unless you are towing a heavy load, are carrying a full payload, or driving hard.
From forum member Patty:
The truck's programming will make many repeated attempts to regenerate the DPF, from a high soot mass level of 65% down to <10% when a cycle is complete. If your trip is too short and the engine is then shut off, or the truck is put in park with the engine idling, an active regeneration process stops (at whatever soot level the DPF is at). The next drive cycle when the DPF again reaches 65% soot mass the whole process starts all over again. If you are going on a road trip the complete cycle will happen many times over... up to 65%... regen... down to <10%... over and over again.
The following information from the Owners Manual:
EVIC Messages
Your vehicle has the ability to alert you to additional maintenance required on your vehicle or engine. Refer to the following messages that may be displayed on your Electronic Vehicle Information Center (EVIC):
• Exhaust Filter XX% Full Safely Drive at Highway Speeds to Remedy — This message will be displayed on the Electronic Vehicle Information Center (EVIC) if the exhaust particulate filter reaches 80% of its maximum storage capacity. Under conditions of exclusive
short duration and low speed driving cycles, your diesel engine and exhaust after-treatment system may never reach the conditions required to cleanse the filter to remove the trapped PM. If this occurs, the “Exhaust Filter XX% Full Safely Drive at Highway Speeds to Remedy” message will be displayed in the EVIC. If this message is displayed, you will hear one chime to assist in alerting you of this condition.
By simply driving your vehicle at highway speeds for up to 20 minutes, you can remedy the condition in the particulate filter system and allow your diesel engine and exhaust after-treatment system to cleanse the filter to remove the trapped PM and restore the system to
normal operating condition.
• Exhaust System — Regeneration In Process Exhaust
Filter XX% Full — This message indicates that the Diesel Particulate Filter (DPF) is self-cleaning. Maintain your current driving condition until regeneration is completed.
• Exhaust System — Regeneration Completed — This message indicates that the Diesel Particulate Filter (DPF) self-cleaning is completed. If this message is displayed, you will hear one chime to assist in alerting you of this condition.
• Exhaust Service Required — See Dealer Now — This messages indicates regeneration has been disabled due to a system malfunction. At this point the engine Powertrain Control Module (PCM) will register a fault code, the instrument panel will display a MIL light.
• Exhaust Filter Full — Power Reduced See Dealer — This message indicates the PCM has derated the engine to limit the likelihood of permanent damage to the after-treatment system. If this condition is not corrected and a dealer service is not performed, extensive
exhaust after-treatment damage can occur. To correct this condition it will be necessary to have your vehicle serviced by your local authorized dealer.
CAUTION!
See your authorized dealer, as damage to the exhaust system could occur soon with continued operation.
Soot Loading Strategy (Quoted from Forum Sponsor GDE)
The ECU runs two different strategies in parallel and takes the higher of the two outputs to determine the current soot loading:
Strategy 1 is a simulated value, and is calculated according to how complete the previous regeneration was, and how the engine/vehicle has been operating since then (engine speed, load, ambient conditions, exhaust temps, etc). Different OEMs design different variations of such a strategy, but for the most part the high level concepts are similar. The strategy employed by the Ram's stock tune is fairly rudimentary.
Strategy 2 is a physically measured value calculated off of measured pressure drop across the DPF, the DPF temperature, and the known flow rate of exhaust gasses.
The soot loading is used to trigger the regeneration when all the correct criteria are met.
Just as a note for some more info...
Passive regens happen when there is sufficient exhaust temperature and a favorable NO2/NOx ratio for the soot to burn. This phenomena will happen starting with exhaust temps in the 380-400°C range.
However... the stock tunes are not capable to detect that passive regeneration is taking place, and to thus slow the modeled accumulation of soot and/or decrease it if the burn rate exceeds the production rate. This is why the intervals are not improved more in the highway cycles.
...we fixed this with our tunes, in order to avoid regenerating when it's not necessary.
).
