Owners Manual and DPF?

[rickinAZ]

I scanned the owners manual supplement, but didn't see any info on how driving style impacts regeneration, or anything about the DPF at all. Did I just miss it? Seems like an appropriate subject to be discussed in the manual.

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[BuffaloBill]

I’m guessing fca wants this to be totally transparent to the user, thinking that the buyer just wants to get in and drive it. But little do they know, we Jeep people are mechanically inclined and have an interest in such things. Likewise, I wish they’d indicate on the dash display, when a regen is in process, or when one is about to begin, etc.

 

[2020 Diesel JL]

I’m guessing fca wants this to be totally transparent to the user, thinking that the buyer just wants to get in and drive it. But little do they know, we Jeep people are mechanically inclined and have an interest in such things. Likewise, I wish they’d indicate on the dash display, when a regen is in process, or when one is about to begin, etc.

I agree that there should be some info in the owner's manual supplement but I also believe that a lot of owners are worring way to much about a regen. If the DPF is up to temp, about 550 deg, the DPF will burn off 90% of the soot produced without ever needing to regen. Yes its a filter in the sense that nothing gets through it without going through the catalyst but it doesn't sit there like an air filter and just plugs up. The catalyst reacts at high temp to burn the soot. If the injectors are atomizing the fuel properly and and the engine is not over fueling it can go thousands of miles without ever needing to perform a regen.

Imagine taking a gallon of fuel and spreading it over a 30 mile run. Very little fuel is being used every minute. If you can remember before 2007 when DPF systems were mandated the only time you really noticed soot coming from a diesel was during take off or heavy load conditions like pulling a hill. Other than those times a diesel is very efficient in the burning of the fuel. Fuel systems now are running at 25,000 to 39,000 PSI to properly atomize the fuel to produce a very clean burn at any speed or RPM.

 

[BuffaloBill]

Thermally, It’s also good that the dpf is located fairly close to the engine rather than farther back.

 

[GARRIGA]

My grasp is that city driving and idling is the main culprit of soot build up due to unburned fuel. Unfortunately, that’s part of my daily commute. Fortunately, so is a larger portion of highway and I can keep driving that highway should a regen initiate. Perhaps knowing the limitations and adjusting one’s driving is all that’s needed to control my fear with soot.

 

[rickinAZ]

My grasp is that city driving and idling is the main culprit of soot build up due to unburned fuel. Unfortunately, that’s part of my daily commute. Fortunately, so is a larger portion of highway and I can keep driving that highway should a regen initiate. Perhaps knowing the limitations and adjusting one’s driving is all that’s needed to control my fear with soot.

I have the same city driving concern. My research seems to indicate that if one drives all short hops, but occasionally (once a week?) throws in a 20-30 minute highway run, all will be good. Is that the forum members' impression as well?

 

[aros-can]

I have the same city driving concern. My research seems to indicate that if one drives all short hops, but occasionally (once a week?) throws in a 20-30 minute highway run, all will be good. Is that the forum members' impression as well?

Having owned several diesels in europe, some with upto 180k miles on them, I never had a problem with DPFs.

Run them on good quality fuel, and yes, a decent run once a week should be all you need.

I always noticed when it was doing a regen as the instant fuel economy was quite obviously lower than it would usually be in those driving circumstances (this usuall followed several days of low speed only commuting to work). If I noticed that as I was 2 minutes away from arriving at home, I'd continue past and go for a 15 min blast up the main road and back.

A side note, it is also good practice to let the diesel idle for a minute or two after 'heavier' driving before shutting off, otherwise the turbo is still nice and toasty when the oil supply is shut off, cooking the oil in the turbo at the time.

 

[Megatron JLU]

Having owned several diesels in europe, some with upto 180k miles on them, I never had a problem with DPFs.

Run them on good quality fuel, and yes, a decent run once a week should be all you need.

I always noticed when it was doing a regen as the instant fuel economy was quite obviously lower than it would usually be in those driving circumstances (this usuall followed several days of low speed only commuting to work). If I noticed that as I was 2 minutes away from arriving at home, I'd continue past and go for a 15 min blast up the main road and back.

A side note, it is also good practice to let the diesel idle for a minute or two after 'heavier' driving before shutting off, otherwise the turbo is still nice and toasty when the oil supply is shut off, cooking the oil in the turbo at the time.

These turbos are water cooled.

 

[2020 Diesel JL]

These turbos are water cooled.

Yes the turbo is also water cooled but the cool down time is for the main shaft bearing that is oils lubricated. A hot turbo spinning a 10,000 rpm needs to cool and slow down. Last night I had to take a quick run to work because I had a transfer load from another location showing up . I got that look from my wife about going in to work over the weekend so I ran the Jeep pretty hard there and back. It was the first time I really ran it hard. I always left it in auto stop / start figuring I would show the best MPG that way and it didn't really bother me. Everytime it starts I think of how many starters will I be replacing during the time I own this, I thought to myself the manufacturer knows what their doing, no big deal. Then as I came up to the third red light within a mile it dawned on me that it is shutting off the second I stop and the turbo has to be toasty with the way I am driving it.
Point of the story I believe the auto stop / start is going to cause a lot of turbo damage due to no lubrication. I will be programing the auto stop / start off with the Tazer today. I have no big issue with replacing a starter earlier than normal but I am not wanting to pay for a turbo and the damage it can do to the DPF system as it starts dumping oil into it when the bearing and seals fail.

 

[aros-can]

Yes the turbo is also water cooled but the cool down time is for the main shaft bearing
Point of the story I believe the auto stop / start is going to cause a lot of turbo damage due to no lubrication. I will be programing the auto stop / start off with the Tazer today. I have no big issue with replacing a starter earlier than normal but I am not wanting to pay for a turbo and the damage it can do to the DPF system as it starts dumping oil into it when the bearing and seals fail.

This.

Although, I don't think its an issue of no lubrication. I have no issue using stop start on my V6 JL, everything is coated in an oil film and bearings are designed for stop start applications now.

The issue is that that oil in the turbo bearings will get very hot very quickly when the oil supply stops in a stop/start cycle. That little bit of oil will get cooked, and you'll increase the chances of sludge etc. Granted, modern oils are designed for this kind of abuse now, but couple that with diesel/oil dilution due to the DPF regens, I think avoiding stop starts in that kind of situation gives it the best long term chance. If you're just pottering around town, then I doubt its an issue. Its when it comes to a stop immediately after some 'spirited' driving.

Its always good practice to idle a diesel for a minute initially and before shutting off if driven hard. I've always just taken my seatbelt off, found my phone etc. then shut off and jumped out. I read somewhere that VM Motiri actually recommend a 2 minute idle at start up and shut down for their engines (of which the ecodiesel is).

 

[aros-can]

The problem I've found in my experience with diesel and DPFs is that they can mask issues, and you end up with a downward spiral as things escalate.

E.g. turbo seals start leaking a small amount of oil into the intake. This would usually be evident by some blue smoke on a normal car. With a DPF, it catches the excess emissions, you see no smoke and not aware of an issue. The DPF then clogs as the ash from burnt oil wont burn off during a regen. I've seen people endlessly chasing DPF issues when caused by something else entirely.

Hopefully knowledge of these emissions devices has caught up, and people know how to diagnose properly, especially over here in the US/Canada where diesel isn't the norm.

 

[2020 Diesel JL]

This.

Although, I don't think its an issue of no lubrication. I have no issue using stop start on my V6 JL, everything is coated in an oil film and bearings are designed for stop start applications now.

The issue is that that oil in the turbo bearings will get very hot very quickly when the oil supply stops in a stop/start cycle. That little bit of oil will get cooked, and you'll increase the chances of sludge etc. Granted, modern oils are designed for this kind of abuse now, but couple that with diesel/oil dilution due to the DPF regens, I think avoiding stop starts in that kind of situation gives it the best long term chance. If you're just pottering around town, then I doubt its an issue. Its when it comes to a stop immediately after some 'spirited' driving.

Its always good practice to idle a diesel for a minute initially and before shutting off if driven hard. I've always just taken my seatbelt off, found my phone etc. then shut off and jumped out. I read somewhere that VM Motiri actually recommend a 2 minute idle at start up and shut down for their engines (of which the ecodiesel is).

DPF regens have do not cause diesel/oil dilution. Whoever said that has no idea how the system works. I would love to have someone explain how that could possibly happen.
With the speeds the turbo shaft spins there is nothing that I know of that you could coat the bearings with that would take that kind of abuse over time.

 

[aros-can]

DPF regens have do not cause diesel/oil dilution. Whoever said that has no idea how the system works. I would love to have someone explain how that could possibly happen.
With the speeds the turbo shaft spins there is nothing that I know of that you could coat the bearings with that would take that kind of abuse over time.

No offence..... but if you know how the system works, you would know that DPFs do and have been shown to cause diesel/oil dilution. To create regen condition (very very hot combustion temps), extra fuel is injected into the engine to start the regen process. 99% of vehicles in Europe do not have oil life monitors or the like, however when DPFs were introduced, I have experience with several that introduced oil service lights that were purely triggered by calculations that determined likely oil dilution levels due to the number of failed/attempted/successful 'active' regen cycles.

"A significant disadvantage associated with active regeneration is the dilution of the engine oil caused by a small amount of diesel during the post-injection cycles, where fuel is injected into the cylinder after the regular combustion. A thin layer of fuel can build up on the cylinder walls, which leads to premature engine wear, and drivers are warned to consider shorter oil service intervals.

There have been various studies into the engine oil dilution issue and the scale of the problem varies according to the make and model of the diesel car in question. Evidence suggests that the problem is worsened when the regeneration process is halted prematurely or when a car is used for short trips."

Some cars are notorious for this. Just google it.

"In modern light-duty Diesel vehicles the particulate filters in the exhaust system require periodic regeneration to prevent plugging. The regeneration procedure is a major cause of dilution of engine oil with diesel fuel. The dilution of engine oil with fuel in diesel engines is not a new issue, but with lowering emission limits it gained more attention recently. Modern light-duty diesel vehicles are equipped with diesel particulate filters (DPF) in the exhaust system accumulating the soot emissions. To prevent plugging these filters need to be regenerated periodically by adding unburned fuel into the exhaust system to burn off the soot. Many manufacturers implement in-cylinder post-injection cycles, where fuel is injected into the cylinder after the regular combustion (at the end of the power stroke and during exhaust stroke). During these late injections, a thin film of fuel can build up on the cylinder walls and be wiped by the piston into the lubrication system of the engine where it dilutes the engine oil [1,2]."

 

[GtX]

You seem to be providing a reference but didn't actually provide the reference. Where it's the info from?

I'd like to read more.

 

[2020 Diesel JL]

No offence..... but if you know how the system works, you would know that DPFs do and have been shown to cause diesel/oil dilution. To create regen condition (very very hot combustion temps), extra fuel is injected into the engine to start the regen process. 99% of vehicles in Europe do not have oil life monitors or the like, however when DPFs were introduced, I have experience with several that introduced oil service lights that were purely triggered by calculations that determined likely oil dilution levels due to the number of failed/attempted/successful 'active' regen cycles.

"A significant disadvantage associated with active regeneration is the dilution of the engine oil caused by a small amount of diesel during the post-injection cycles, where fuel is injected into the cylinder after the regular combustion. A thin layer of fuel can build up on the cylinder walls, which leads to premature engine wear, and drivers are warned to consider shorter oil service intervals.

There have been various studies into the engine oil dilution issue and the scale of the problem varies according to the make and model of the diesel car in question. Evidence suggests that the problem is worsened when the regeneration process is halted prematurely or when a car is used for short trips."

Some cars are notorious for this. Just google it.

"In modern light-duty Diesel vehicles the particulate filters in the exhaust system require periodic regeneration to prevent plugging. The regeneration procedure is a major cause of dilution of engine oil with diesel fuel. The dilution of engine oil with fuel in diesel engines is not a new issue, but with lowering emission limits it gained more attention recently. Modern light-duty diesel vehicles are equipped with diesel particulate filters (DPF) in the exhaust system accumulating the soot emissions. To prevent plugging these filters need to be regenerated periodically by adding unburned fuel into the exhaust system to burn off the soot. Many manufacturers implement in-cylinder post-injection cycles, where fuel is injected into the cylinder after the regular combustion (at the end of the power stroke and during exhaust stroke). During these late injections, a thin film of fuel can build up on the cylinder walls and be wiped by the piston into the lubrication system of the engine where it dilutes the engine oil [1,2]."

Please explain when and where this fuel is being injected and how the regen works.

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