Passive Regeneration -- Urban Legend?

[Stalwart]

Originally Posted by GEARJAMMER

What build is your truck? When you have a "regeneration," does the message center stay lit with the "CLEANING EXHAUST FILTER" message? Could you have missed the message for "regeneration?" If you go back to my very first post, when I pull hard and I get regular "regenerations." They are to close together to allow for a "passive regeneration." Until I got the latest flash, I believed in the "passive regeneration." I no longer believe this. In fact, it's a real eye opener to see how much the truck does go into "regeneration."

Shawn

Ok Shawn, I have a Job 1 and with the stock flash I could ALWAYS tell a regen by the sound of the engine and the 20 lb boost limit. I kid you not, I could "hear it" and would confirm it with the diminished boost. I now have the "TCM Killer" reflash and I now get the message in the dash and less often regens that I can no longer "hear."

When I was towing the heavy load I was coming up to the mileage where I ALWAYS had a regen and I didn't see another for 375 miles AFTER I stopped towing the trailer.

I still doubt very many of us will ever see a passive regen because you would need to keep the EGT's VERY high for so long. I've only missed the one active regen (they come every 350-400 miles) in the 24,000 miles I've driven the truck. With the new flash I cannot tell anymore when they are happening unless I'm looking down, during the 5 or whatever seconds the display tells you the it is starting one.

I just don't think you're pulling hard enough to get a passive one, heck I only missed one and I had to be over Ford's max gross combined vehicle weight rating of my F450 (33,000 lb.) for that to happen. I should also state that I was pulling some pretty steep hills at that weight and I still don't have my Edge InSight installed yet . . .

[GEARJAMMER]

Originally Posted by Greyman

"Passive regen happens whenever exhaust temps exceed approx. 1,076 degrees F without a fuel consumption penalty. Active regens occur when the DPF sensor triggers a burn off and requires the engine to force higher exhaust temps, 1,076 to 1,200 degrees F." This is out of Diesel Power Mag., from the mouth of Charlie Freese a GM duramax engineer. I'm guessing our motor is close to the same.

I'm not an engineer nor do I claim to be smarter than one. I do know that when a diesel works hard enough to get the "EGT's" into the 1,000 to 1,200 degrees F that motor is putting out a lot of black smoke a.k.a. soot. Look at a truck without a "DPF." I have to be putting out more soot than what is being burnt off in a so called "passive regeneration."

Originally Posted by Stalwart

Ok Shawn, I have a Job 1 and with the stock flash I could ALWAYS tell a regen by the sound of the engine and the 20 lb boost limit. I kid you not, I could "hear it" and would confirm it with the diminished boost. I now have the "TCM Killer" reflash and I now get the message in the dash and less often regens that I can no longer "hear."

When I was towing the heavy load I was coming up to the mileage where I ALWAYS had a regen and I didn't see another for 375 miles AFTER I stopped towing the trailer.

I still doubt very many of us will ever see a passive regen because you would need to keep the EGT's VERY high for so long. I've only missed the one active regen (they come every 350-400 miles) in the 24,000 miles I've driven the truck. With the new flash I cannot tell anymore when they are happening unless I'm looking down, during the 5 or whatever seconds the display tells you the it is starting one.

I just don't think you're pulling hard enough to get a passive one, heck I only missed one and I had to be over Ford's max gross combined vehicle weight rating of my F450 (33,000 lb.) for that to happen. I should also state that I was pulling some pretty steep hills at that weight and I still don't have my Edge InSight installed yet . . .

I'm not sure, but I think you do not have the same flash as mine. My message center would flash momentarily "CLEANING EXHAUST FILTER." Now, when my message center states "CLEANING EHAUST FILTER" it stays on until the "regeneration" is complete or I hit reset. Before I had this latest flash and the message would come up momentarily it was easy to miss a "regeneration" but if you hit setup and then reset for an engine check it show the "regeneration" in the engine check.

I'm working my truck hard enough. I pull a 41 foot "CYCLONE" toy hauler. Two (2) dressers in the back and 110 gallons of fresh water. I carry 103 gallons of fuel on board with all of my tools, including air tools, a dog , a cat, and three (3) other people. If I'm running out on the plains I get a "regeneration" about every 100 miles and they last for about 10 miles. When I'm pulling in the mountains the "regenerations" come closer. There isn't any time for a "passive regeneration."

Shawn

[Stalwart]

That's wierd Shawn but your're kinda off on the "diesel works hard enough . . . motor is putting out a lot of black smoke a.k.a. soot.". On most modern Diesels during ACCELERATION you will see a brief bit of smoke but once the airflow is up (turbos spooled up) you will get VERY little or no smoke at all, in STOCK form. Altering the programming throws this all out the window but I haven't seen one single newer stock diesel make visable smoke or soot under heavy load. I have seen most smoke on acceleration, my '08 included, but that's just my cracked DPF.

I do agree we are probably running different ECU flashes since mine was done about a month ago. All I can say is when I pulled mine HARD, it didn't regen for about 750+ miles.

[GEARJAMMER]

Originally Posted by Stalwart

That's weird Shawn but you're kinda off on the "diesel works hard enough . . . motor is putting out a lot of black smoke a.k.a. soot.". On most modern Diesels during ACCELERATION you will see a brief bit of smoke but once the airflow is up (turbos spooled up) you will get VERY little or no smoke at all, in STOCK form. Altering the programming throws this all out the window but I haven't seen one single newer stock diesel make visible smoke or soot under heavy load. I have seen most smoke on acceleration, my '08 included, but that's just my cracked DPF.

I do agree we are probably running different ECU flashes since mine was done about a month ago. All I can say is when I pulled mine HARD, it didn't regen for about 750+ miles.

Stalwart, I'm running the 08B07 flash. It's the one they had to stop because it was killing the TCM's. I didn't have a problem with mine.

You are correct that the newer diesels do not smoke as much as the older ones. My son-in-law has an 06 F-350 and when he is towing heavy you can see a small amount smoke, especially when he climbs something as simple as an overpass on the interstate. The tail pipes on my 08 are clean.

I had to go to my dealership today and I talked to my friend Gary who is a Diesel Master Tech and the service manager, who in his day was pretty good wrench, about "passive regenerations." Chris the service manager started laughing and agreed with me as did Gary. Chris told me that he had to talk to a diesel engine engineer and that he was going to bring the subjuct up concerning "passive regenerations" Chris told me that he'd get back to me and let me know what the engineer said. As soon as i know, I'll post an update.

Shawn

[gossamar]

Okay, had my second regen on my trip back from Minnesota yesterday and here are some observations. For the first 5-10 minutes of the regen the egt's were only running about 800 versus 600 for normal driving. After 10 minutes or so, the egts shot up to 1150-1200 for the next 5-10 minutes. My first regen that I know about was at around 700 miles on the truck, the next regen happened at 1390, so as of now, I am averaging regens about every 700-miles or so.

[LandShark-47]

I never see smoke/soot anytime and my regens aren't for more than ten minutes at 40-50 mph daily driving. I have no idea what the EGT's are since I don't have a gauge (should be a stock option). The only time my regen was more than 10 mins was its first while towing a 12k toyhauler. That lasted 54 miles and the truck only had 1100 miles on it. Otherwise towing the regens are brief.

08 f350 3.73's CCLB production date of 04/08