Is 3.0 ED right for me? Driving Distance Question

Capricorn

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You might want to read on passive regenerations. A passive “regen” is when the DPF burns off soot due to higher engine loads and exhaust temperatures. It requires no intervention from the motor or ECU.

https://www.uti.edu/blog/diesel/diesel-particulate-filters
That’s not how the emissions system works. The DPF accumulates soot until it reaches its capacity and then performs a regen to burn off the soot. The Eco Diesel typically goes into active regen mode at about 80% Soot percentage and will drop down to 10 or so % after it completes the regen. My ZR2 Bison Duramax goes into regen at 100% DPF capacity so all are different. Point being is that the engine must regen to burn off soot.
If a vehicle's exhaust keeps reaching temperatures to burn off soot through enough load, they would not get to the stage of 80% accumulation for active regen to happen.

Passive regen - soot being burned without intervention while driving with enough load to get to high exhaust temps.
Active regen - soot being burned off due to ECU intervention if it reaches 80% soot accumulation.
Forced regen - when either of the above two modes fail.

That is my understanding.





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WXman

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If a vehicle's exhaust keeps reaching temperatures to burn off soot through enough load, they would not get to the stage of 80% accumulation for active regen to happen.

Passive regen - soot being burned without intervention while driving with enough load to get to high exhaust temps.
Active regen - soot being burned off due to ECU intervention if it reaches 80% soot accumulation.
Forced regen - when either of the above two modes fail.

That is my understanding.
This is correct and like I've mentioned in several threads, 650F seems to be the magic threshold on mine. I monitor turbo and DPF temps with a Scan Gauge II and I notice that at or above 650F my DPF will naturally be cleaned by the heat. Below 650F it will not clean on its own and will accumulate soot steadily.

I ONLY see the DPF reach 650F when I'm towing a trailer, or when I'm driving at 65 MPH or faster.

Also, I've only seen regen status "ON" with the Scan Gauge once or twice since summer because it happens so fast and so quietly on the Gen 3 engine that it's easy to miss. Once it went into regen near 80% but the other time it was only around 60%, so I think there's more to the programming than simply a hard 80% rule.
 

Capricorn

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This is correct and like I've mentioned in several threads, 650F seems to be the magic threshold on mine. I monitor turbo and DPF temps with a Scan Gauge II and I notice that at or above 650F my DPF will naturally be cleaned by the heat. Below 650F it will not clean on its own and will accumulate soot steadily.

I ONLY see the DPF reach 650F when I'm towing a trailer, or when I'm driving at 65 MPH or faster.

Also, I've only seen regen status "ON" with the Scan Gauge once or twice since summer because it happens so fast and so quietly on the Gen 3 engine that it's easy to miss. Once it went into regen near 80% but the other time it was only around 60%, so I think there's more to the programming than simply a hard 80% rule.
Yes, the 80% mark may not be a hard rule. On some RAM forums I read that active regen can start at 65% too. It depends on how it is programmed.
Since I don't have a Scan Guage, it is good useful info to know at what point the DPF or exhaust temps get to 650℉. I don't tow, so only freeway/highway driving is where I expect to put some load on the engine. And 90% of my miles come with highway driving.

I am sure there is a correlation between oil temp and exhaust temp too on the highway and can that be used as a rough calculation? I mean if I am at 212℉ oil temp on a highway driving continuously for 10 minutes at or above speed limit, is it likely that I am at about 3 times the temperature in the exhaust?

With city driving, oil temp at 212℉ may not be a good indicator to use to estimate the exhaust temps since there may not be turbo boost in that situation.
 

WXman

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Yes, the 80% mark may not be a hard rule. On some RAM forums I read that active regen can start at 65% too. It depends on how it is programmed.
Since I don't have a Scan Guage, it is good useful info to know at what point the DPF or exhaust temps get to 650℉. I don't tow, so only freeway/highway driving is where I expect to put some load on the engine. And 90% of my miles come with highway driving.

I am sure there is a correlation between oil temp and exhaust temp too on the highway and can that be used as a rough calculation? I mean if I am at 212℉ oil temp on a highway driving continuously for 10 minutes at or above speed limit, is it likely that I am at about 3 times the temperature in the exhaust?

With city driving, oil temp at 212℉ may not be a good indicator to use to estimate the exhaust temps since there may not be turbo boost in that situation.
What I generally see is that while cruising on the highway I'm between 600-800F at the turbo. The highest I have ever seen it is in the 1,100 degrees F range and that's while towing uphill. Normally it's always below 800 degrees. Boost varies obviously depending on terrain but on a flat, straight stretch of highway it'll only run at 3-4 lbs of boost.

On the Ram, they've got the tune set up to limit boost to 22.7 PSI maximum. I would love to see what the maximum is on the Jeep. I suspect that it's lower and that's how they were able to detune the engine in the Jeep application. If so, aftermarket tuners next year will be able to easily tune the Jeep version at or above the Ram's 480 lb/ft.

Another side benefit of the gauge is that when I park I can watch the turbo temperature fall rapidly and once it's to a safe level (for me I'm looking for <450 degrees) I go ahead and shut the engine down.
 

Capricorn

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Another side benefit of the gauge is that when I park I can watch the turbo temperature fall rapidly and once it's to a safe level (for me I'm looking for <450 degrees) I go ahead and shut the engine down.
I am curious how quickly the turbo cools down if you are gently driving at 25-30mph for 5 minutes after exiting the highway. In my case, my home is about 2 miles away from the highway exit and I get at least one stop light. In that situation, you think my turbo may have cooled down to below 450℉ by the time I get to my driveway? I still idle for 30-40 seconds just in case but I am wondering even if that would be necessary.
 

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If a vehicle's exhaust keeps reaching temperatures to burn off soot through enough load, they would not get to the stage of 80% accumulation for active regen to happen.

Passive regen - soot being burned without intervention while driving with enough load to get to high exhaust temps.
Active regen - soot being burned off due to ECU intervention if it reaches 80% soot accumulation.
Forced regen - when either of the above two modes fail.

That is my understanding.
This is very interesting...I monitor all 3 of my diesels (Cummins, Duramax and the Eco Diesel) and I have never seen the DPF soot levels drop without a regen occurring. Loaded, unloaded, working hard etc.
 

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I am curious how quickly the turbo cools down if you are gently driving at 25-30mph for 5 minutes after exiting the highway. In my case, my home is about 2 miles away from the highway exit and I get at least one stop light. In that situation, you think my turbo may have cooled down to below 450℉ by the time I get to my driveway? I still idle for 30-40 seconds just in case but I am wondering even if that would be necessary.
Yes you would be surprised at how fast it cools off. The Gen 3 engine uses oil AND water cooling and once you take all the load off the engine the turbo cools off pretty fast. If you're gently coasting at 30 MPH and rarely using the throttle it's likely that your turbo temp is below 500 degrees.
 
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What I generally see is that while cruising on the highway I'm between 600-800F at the turbo. The highest I have ever seen it is in the 1,100 degrees F range and that's while towing uphill. Normally it's always below 800 degrees. Boost varies obviously depending on terrain but on a flat, straight stretch of highway it'll only run at 3-4 lbs of boost.

On the Ram, they've got the tune set up to limit boost to 22.7 PSI maximum. I would love to see what the maximum is on the Jeep. I suspect that it's lower and that's how they were able to detune the engine in the Jeep application. If so, aftermarket tuners next year will be able to easily tune the Jeep version at or above the Ram's 480 lb/ft.

Another side benefit of the gauge is that when I park I can watch the turbo temperature fall rapidly and once it's to a safe level (for me I'm looking for <450 degrees) I go ahead and shut the engine down.
From my observations, I don't think that the Scan Gauge reads pressures above 22.7 PSI. I have noticed that when it reads pressures of 22.7, my TazerJL will read higher. The highest I've seen is 28 PSI.
 

Russ Chung

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Another side benefit of the gauge is that when I park I can watch the turbo temperature fall rapidly and once it's to a safe level (for me I'm looking for <450 degrees) I go ahead and shut the engine down.
I would not assume that just because the EGT has cooled down, it is OK to shut off the engine. The reason for idling the engine before shutting down is to allow the housing around the turbocharger bearings to cool down. AFAIK, there is no sensor or indicator to tell us what the temp of the turbocharger housing is and I assume that the housing cools down more slowly than the EGT. For lack of a better indicator, I use the chart in the owners' manual: if the turbo is cool, no idle is necessary; if the turbo is warm, idle for one minute; if the turbo is hot, idle for 2-1/2 minutes. And if the ambient temperature is high, I open the hood to allow it to cool down faster.
 

rickinAZ

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Being retired, I don’t commute or take many long trips. My filter fills up, the regen system burns it up. If you are still concerned, you can install a Banks or Scangauge gauge to monitor (realtime) all the diesel-related systems. Many of us have them.

buy, drive, enjoy
 

WXman

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I would not assume that just because the EGT has cooled down, it is OK to shut off the engine. The reason for idling the engine before shutting down is to allow the housing around the turbocharger bearings to cool down. AFAIK, there is no sensor or indicator to tell us what the temp of the turbocharger housing is and I assume that the housing cools down more slowly than the EGT. For lack of a better indicator, I use the chart in the owners' manual: if the turbo is cool, no idle is necessary; if the turbo is warm, idle for one minute; if the turbo is hot, idle for 2-1/2 minutes. And if the ambient temperature is high, I open the hood to allow it to cool down faster.
Right, but how do you know if the turbo is cool? The only reading we can get is the turbo temp. reading and that's all we've got to go on. There's no way to measure the temp of the bearing itself.

Also, there is a pump that apparently flows coolant through the turbo even after shut-down, which is the noise that people have talked about in another thread. So the vehicle controls have safety features built in to protect the components. A combo of this and watching turbo temps on a gauge is plenty to ensure a long life.
 

Capricorn

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Right, but how do you know if the turbo is cool? The only reading we can get is the turbo temp. reading and that's all we've got to go on. There's no way to measure the temp of the bearing itself.

Also, there is a pump that apparently flows coolant through the turbo even after shut-down, which is the noise that people have talked about in another thread. So the vehicle controls have safety features built in to protect the components. A combo of this and watching turbo temps on a gauge is plenty to ensure a long life.
And synthetic oil is a plus too, in preventing coking.
 

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