Passive regeneration

[Paul Markowski]

What is meant by "Passive Regen" and how does one know it may be happening?

 

[Newsa]

Passive regen is when your truck is working hard under load and the exhaust gas temps reach over 1000° F. Some in the know say EGT's actually need to exceed 1200° for passive regen. You won't know when passive regen occurs unless you purchase a device that monitors DPF differential pressure, EGT, and/or soot load.because the truck doesn't do anything to increase EGT's. High temps are required to burn off collected soot in the Diesel Particulate Filter.

 

[6V92TA]

I'm going to quote directly from the ISB Service Manual a longer explanation of what is going on in the DPF as far as regeneration . I can't say for sure if every parammeter is the same on a Ram Truck but they should be close... QUOTE: "Passive regeneration occurs when the exhaust temperatures are naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than the soot is collected.

Passive regeneration typically occurs when the temperature of the aftertreatment DPF is above 316°C [600°F]. This occurs during highway driving or when driving with heavy loads.

Since passive regeneration occurs naturally, it is considered to be normal engine operation. No fuel is added to the exhaust stream during passive regeneration. Active regeneration occurs when the exhaust temperatures are not naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than it is collected.

Active regeneration requires assistance from the engine in order to increase the exhaust temperature. This is typically done by injecting a small amount of diesel fuel into the exhaust stream (called aftertreatment injection) which is then oxidized by the aftertreatment DOC. The oxidation of this additional fuel creates the heat needed to regenerate the aftertreatment DPF.

For active regeneration to occur, the ECM must detect that the aftertreatment DPF restriction has reached a specified limit. Once this limit is reached, the engine will alter its operation in order to create exhaust temperatures high enough to actively regenerate the aftertreatment DPF.Aftertreatment injection requires that temperatures in the aftertreatment system reach approximately 288°C [550°F]. At this temperature and above, the small quantities of fuel injected into the exhaust will properly oxidize across the aftertreatment DOC, creating the additional heat required to actively regenerate the aftertreatment DPF.

During active regeneration, the engine ECM monitors the exhaust temperatures before and after the DPF and maintains the temperatures in a range of approximately 482 to 649°C [900 to 1200°F]. The quantity of fuel used for aftertreatment injection will vary as the temperature is controlled within these limits.

The temperatures achieved during active regeneration are typically higher than those achieved during passive regeneration. The conversion of soot to carbon dioxide occurs much faster as temperatures increase.

A typical active regeneration event will take approximately 20 to 40 minutes to complete while the vehicle is operating. The vehicle operator may notice additional turbocharger noise during this time, along with an illuminated high exhaust temperature lamp, if equipped.

The frequency at which an engine will require an active regeneration varies greatly from application to application. In general, vehicles with a low vehicle speed, such as urban vehicles, or a low-load duty cycle, will require more active regeneration events than a heavily loaded vehicle or a vehicle with a highway speed duty cycle.

The engine ECM also contains a time-based feature for active regenerations, which is used to verify correct aftertreatment operation when the vehicle duty cycle is typically high enough that active regeneration events are not necessary.

If the engine has not completed an active regeneration within the last 24 hours of operation, the engine ECM will call for a time-based active regeneration event.

The 24-hour timer resets each time the ECM detects that an active regeneration event has been completed.

Under some operating conditions, such as low speed, low load, or stop-and-go duty cycles, the engine may not have enough opportunity to regenerate the DPF during normal vehicle operation. When this occurs, the engine illuminates the DPF lamp to inform the vehicle operator that assistance is required, typically in the form of a stationary (parked) regeneration.

Stationary (parked) regeneration is a form of active regeneration that is initiated by the vehicle operator when the vehicle is not moving. QUOTE

 

[Deleted member 995608]

This needs to be a sticky

 

[kthaxton]

This needs to be a sticky

That's for sure.

I think the confusion for some is because of the two different scenarios of an "active" regen, not realizing that they are both, still considered "active" i.e.:

-a regular active regen that happens somewhat frequently (depending on use) which the truck gives you no indication it is taking place (unless you have a monitor of some type) or...

-the scenario where the DPF is critically plugged and the evic gives you an indication that regen is taking place......I think many people think only this scenario is considered "active".

They are both "active", as explained in the quote above, because the PCM is actually making a change, it is "actively" heating up the exhaust by calling for fuel in the exhaust stroke. "Passive", meaning the engine/PCM are just going about their usual business, just that the engine is working hard enough to produce enough heat on its own.

 

[Bob4x4]

There are differences from model to model.The quote above is a late model version.The 24 hour portion was added during the def era.

 

[CoastyAV8R]

I saw a person may note a higher turbo pitch when active regen takes place, short of that is there any indication? My fear is turning off my truck during an active regen cycle as I have no EGT gauge to give me an indication it's cleaning itself out.

 

[Newsa]

I'm going to quote directly from the ISB Service Manual a longer explanation of what is going on in the DPF as far as regeneration . I can't say for sure if every parammeter is the same on a Ram Truck but they should be close... QUOTE: "Passive regeneration occurs when the exhaust temperatures are naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than the soot is collected.

Passive regeneration typically occurs when the temperature of the aftertreatment DPF is above 316°C [600°F]. This occurs during highway driving or when driving with heavy loads.

Since passive regeneration occurs naturally, it is considered to be normal engine operation. No fuel is added to the exhaust stream during passive regeneration. Active regeneration occurs when the exhaust temperatures are not naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than it is collected.

Active regeneration requires assistance from the engine in order to increase the exhaust temperature. This is typically done by injecting a small amount of diesel fuel into the exhaust stream (called aftertreatment injection) which is then oxidized by the aftertreatment DOC. The oxidation of this additional fuel creates the heat needed to regenerate the aftertreatment DPF.

For active regeneration to occur, the ECM must detect that the aftertreatment DPF restriction has reached a specified limit. Once this limit is reached, the engine will alter its operation in order to create exhaust temperatures high enough to actively regenerate the aftertreatment DPF.Aftertreatment injection requires that temperatures in the aftertreatment system reach approximately 288°C [550°F]. At this temperature and above, the small quantities of fuel injected into the exhaust will properly oxidize across the aftertreatment DOC, creating the additional heat required to actively regenerate the aftertreatment DPF.

During active regeneration, the engine ECM monitors the exhaust temperatures before and after the DPF and maintains the temperatures in a range of approximately 482 to 649°C [900 to 1200°F]. The quantity of fuel used for aftertreatment injection will vary as the temperature is controlled within these limits.

The temperatures achieved during active regeneration are typically higher than those achieved during passive regeneration. The conversion of soot to carbon dioxide occurs much faster as temperatures increase.

A typical active regeneration event will take approximately 20 to 40 minutes to complete while the vehicle is operating. The vehicle operator may notice additional turbocharger noise during this time, along with an illuminated high exhaust temperature lamp, if equipped.

The frequency at which an engine will require an active regeneration varies greatly from application to application. In general, vehicles with a low vehicle speed, such as urban vehicles, or a low-load duty cycle, will require more active regeneration events than a heavily loaded vehicle or a vehicle with a highway speed duty cycle.

The engine ECM also contains a time-based feature for active regenerations, which is used to verify correct aftertreatment operation when the vehicle duty cycle is typically high enough that active regeneration events are not necessary.

If the engine has not completed an active regeneration within the last 24 hours of operation, the engine ECM will call for a time-based active regeneration event.

The 24-hour timer resets each time the ECM detects that an active regeneration event has been completed.

Under some operating conditions, such as low speed, low load, or stop-and-go duty cycles, the engine may not have enough opportunity to regenerate the DPF during normal vehicle operation. When this occurs, the engine illuminates the DPF lamp to inform the vehicle operator that assistance is required, typically in the form of a stationary (parked) regeneration.

Stationary (parked) regeneration is a form of active regeneration that is initiated by the vehicle operator when the vehicle is not moving. QUOTE

Thanks for the info. I hadn't seen that

 

[6V92TA]

Thanks for the info. I hadn't seen that

Newsa, you are welcome... I'm in the business end of Diesel powered eqipment, among other things I have a Cummins Quickserve account so its easy enough for me to quote any of Cummins Manuals when a question like this comes up... I like to share this info with anyone who asks, straight from the horses mouth... basically there are 3 types of regen... obviously passive, which just happens while driving.... then you have active regen which can occur either when the DPF is restricted and the ECM alters injection and adds some fuel on the exhaust stroke and also Cummins has a program in there with a timer function, which will do a active regen every 25 or so hours if the ECM hasn't detected a Active Regen because of DPF restrictions,... and of course there is also a Stationary Regen procedure , which occurs when this stuff is messed up and a mechanic has to log onto to the system and encourage the engine to clean itself by running a computer program..

 

[Paul Markowski]

I'm going to quote directly from the ISB Service Manual a longer explanation of what is going on in the DPF as far as regeneration . I can't say for sure if every parammeter is the same on a Ram Truck but they should be close... QUOTE: "Passive regeneration occurs when the exhaust temperatures are naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than the soot is collected.

Passive regeneration typically occurs when the temperature of the aftertreatment DPF is above 316°C [600°F]. This occurs during highway driving or when driving with heavy loads.

Since passive regeneration occurs naturally, it is considered to be normal engine operation. No fuel is added to the exhaust stream during passive regeneration. Active regeneration occurs when the exhaust temperatures are not naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than it is collected.

Active regeneration requires assistance from the engine in order to increase the exhaust temperature. This is typically done by injecting a small amount of diesel fuel into the exhaust stream (called aftertreatment injection) which is then oxidized by the aftertreatment DOC. The oxidation of this additional fuel creates the heat needed to regenerate the aftertreatment DPF.

For active regeneration to occur, the ECM must detect that the aftertreatment DPF restriction has reached a specified limit. Once this limit is reached, the engine will alter its operation in order to create exhaust temperatures high enough to actively regenerate the aftertreatment DPF.Aftertreatment injection requires that temperatures in the aftertreatment system reach approximately 288°C [550°F]. At this temperature and above, the small quantities of fuel injected into the exhaust will properly oxidize across the aftertreatment DOC, creating the additional heat required to actively regenerate the aftertreatment DPF.

During active regeneration, the engine ECM monitors the exhaust temperatures before and after the DPF and maintains the temperatures in a range of approximately 482 to 649°C [900 to 1200°F]. The quantity of fuel used for aftertreatment injection will vary as the temperature is controlled within these limits.

The temperatures achieved during active regeneration are typically higher than those achieved during passive regeneration. The conversion of soot to carbon dioxide occurs much faster as temperatures increase.

A typical active regeneration event will take approximately 20 to 40 minutes to complete while the vehicle is operating. The vehicle operator may notice additional turbocharger noise during this time, along with an illuminated high exhaust temperature lamp, if equipped.

The frequency at which an engine will require an active regeneration varies greatly from application to application. In general, vehicles with a low vehicle speed, such as urban vehicles, or a low-load duty cycle, will require more active regeneration events than a heavily loaded vehicle or a vehicle with a highway speed duty cycle.

The engine ECM also contains a time-based feature for active regenerations, which is used to verify correct aftertreatment operation when the vehicle duty cycle is typically high enough that active regeneration events are not necessary.

If the engine has not completed an active regeneration within the last 24 hours of operation, the engine ECM will call for a time-based active regeneration event.

The 24-hour timer resets each time the ECM detects that an active regeneration event has been completed.

Under some operating conditions, such as low speed, low load, or stop-and-go duty cycles, the engine may not have enough opportunity to regenerate the DPF during normal vehicle operation. When this occurs, the engine illuminates the DPF lamp to inform the vehicle operator that assistance is required, typically in the form of a stationary (parked) regeneration.

Stationary (parked) regeneration is a form of active regeneration that is initiated by the vehicle operator when the vehicle is not moving. QUOTE

Awesome stuff...thanks!