active vs passive regen
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Joined: Apr 2017
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active vs passive regen
I finally got the dealer to turn on my DPF gauge (I had to show them how), and I was all excited to see my filter was 85% full. This is my first diesel so I have never felt a regen before.
The truck has 1500 miles so I'm sure I have already went through some, just never noticed it. I got on the highway at 95% full, after a couple miles it went to 99% then...
I was really waiting for a loud sound and a bad smell, that never happened. Because I was watching it I did notice a sound, kike the truck was downshifting sound, but that was it. Was a lot more quiet than I thought it would be.
So of course I flipped over to my fuel gauge and sure enough MPG dropped to about 10. Finny thing was after about 5 min of the regen, my MPG went back up and I couldn't really tell I was in a regen anymore just by the MPG.
I flipped back over to my DPF screen and I was at like 80% and dropping, so I was still in regen, but again the MPG has settled around 16.
So when your on the highway, does it sometimes go into active then switch to passive when it gets hot enough?
The truck has 1500 miles so I'm sure I have already went through some, just never noticed it. I got on the highway at 95% full, after a couple miles it went to 99% then...
I was really waiting for a loud sound and a bad smell, that never happened. Because I was watching it I did notice a sound, kike the truck was downshifting sound, but that was it. Was a lot more quiet than I thought it would be.
So of course I flipped over to my fuel gauge and sure enough MPG dropped to about 10. Finny thing was after about 5 min of the regen, my MPG went back up and I couldn't really tell I was in a regen anymore just by the MPG.
I flipped back over to my DPF screen and I was at like 80% and dropping, so I was still in regen, but again the MPG has settled around 16.
So when your on the highway, does it sometimes go into active then switch to passive when it gets hot enough?
Cross-Country
Joined: May 2011
Posts: 81
Likes: 3
From: St George, UT
On my 2010 6.4L, I could sometimes detect an active regen by a feeling a slight roughness at idle, or a slight change in exhaust tone. It was very subtle, and often undetectable without watching EGT or DPF temps with a ScanGauge or other.
I haven't detected a regen on my 2017 yet, but I only have 500 miles on it... Ford seems to have done a pretty good job at hiding the whole functionality for normal driving.
I used to obsess about letting regents run to completion, but not sure I need to do that any more. Frustrating because invariably, it would start an active regen 5 or less miles from my destination!
I haven't detected a regen on my 2017 yet, but I only have 500 miles on it... Ford seems to have done a pretty good job at hiding the whole functionality for normal driving.
I used to obsess about letting regents run to completion, but not sure I need to do that any more. Frustrating because invariably, it would start an active regen 5 or less miles from my destination!
Elder User
Joined: Nov 2016
Posts: 668
Likes: 6
From: FL
Getting the DPF% enabled was really eye-opening for me. I thought that no matter how full the filter, getting on the highway would kick off a regen; but I, like OP, have noticed that it never starts a regen until the sequence OP described above...95%...99%...then it starts dropping.
I made a lot of 'wasted' highway trips guessing that it was nearly full and hoping a regen would occur.
Another thing I noticed...I think I read here on another post that if your speed fell below 40 mph the regen would stop; but that has not been my experience. Twice, I've been on divided highways and had a regen occur...only to get stopped at an intersection...and as I sat at the light I watched the percentage continue to go down.
IMHO, nothing is going to start it until it's time; and if you keep driving your truck reasonably, nothing is going to stop it until it's done.
I made a lot of 'wasted' highway trips guessing that it was nearly full and hoping a regen would occur.
Another thing I noticed...I think I read here on another post that if your speed fell below 40 mph the regen would stop; but that has not been my experience. Twice, I've been on divided highways and had a regen occur...only to get stopped at an intersection...and as I sat at the light I watched the percentage continue to go down.
IMHO, nothing is going to start it until it's time; and if you keep driving your truck reasonably, nothing is going to stop it until it's done.
Posting Guru
Joined: Jan 2011
Posts: 1,352
Likes: 4
Getting the DPF% enabled was really eye-opening for me. I thought that no matter how full the filter, getting on the highway would kick off a regen; but I, like OP, have noticed that it never starts a regen until the sequence OP described above...95%...99%...then it starts dropping.
I made a lot of 'wasted' highway trips guessing that it was nearly full and hoping a regen would occur.
Another thing I noticed...I think I read here on another post that if your speed fell below 40 mph the regen would stop; but that has not been my experience. Twice, I've been on divided highways and had a regen occur...only to get stopped at an intersection...and as I sat at the light I watched the percentage continue to go down.
IMHO, nothing is going to start it until it's time; and if you keep driving your truck reasonably, nothing is going to stop it until it's done.
I made a lot of 'wasted' highway trips guessing that it was nearly full and hoping a regen would occur.
Another thing I noticed...I think I read here on another post that if your speed fell below 40 mph the regen would stop; but that has not been my experience. Twice, I've been on divided highways and had a regen occur...only to get stopped at an intersection...and as I sat at the light I watched the percentage continue to go down.
IMHO, nothing is going to start it until it's time; and if you keep driving your truck reasonably, nothing is going to stop it until it's done.
Senior User
Joined: Feb 2017
Posts: 377
Likes: 5
Another thing I noticed...I think I read here on another post that if your speed fell below 40 mph the regen would stop; but that has not been my experience. Twice, I've been on divided highways and had a regen occur...only to get stopped at an intersection...and as I sat at the light I watched the percentage continue to go down.
Posting Guru
Joined: Jan 2011
Posts: 1,352
Likes: 4
It has been my understanding that the passive regeneration is always occurring. That in order for the passive regeneration to be effective the exhaust temperature needs to be high enough. That when the filter gets too full an active regeneration occurs and revs the engine to get the exhaust hot enough to clean the particulate filter. I thought I had seen somewhere that during an active regeneration the command module would inject small amounts of diesel just before the exhaust to help heat up the filter quickly, which I think this is why the manual says you might notice the exhaust tone change.
You are not always in a passive regen.
Elder User
Joined: Jan 2004
Posts: 566
Likes: 3
From: Florence SC
Only negative I have seen to parking the truck in the middle of a regen is that one time I saw a bit of visible smoke when regen kicked back on the next time I drove it. Don't know what that was from exactly, but it was that one time when it reactivated regen . I used to worry about regen and tried to drive it out. I don't anymore. Just let it do its thing.
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Senior User
Joined: Feb 2017
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The engine does not rev more during a regen. It just dumps more fuel (about 1.5 gallons of extra diesel on a full regen). Anything around 675 degrees for egts will keep soot at about the same level. Anything around 700-750 will cause a passive regen (egts are high enough for a slow burn down).
You are not always in a passive regen.
You are not always in a passive regen.
Does it burn more in the engine? or somewhere else in the exhaust?
> 'You are not always in a passive regen.'
So does the computer have to be in a 'regen' state for a passive regen to burn off particulates from the filter?
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Posting Guru
Joined: Jan 2011
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A passive regen is anytime you are burning more soot then making. When I tow my camper (40ft 5th at about 13k) at highway speeds, I can get my egts to stay in the 650 - 700 range which maintains my soot level.
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