Since cool weather has came in my gpl levels barely build up, and passive regen has actually kicked in when towing. Now, no matter where my gpl number is, when I roll over 450 miles regen kicks in. Takes it down about 1.6gpl. During summer my regens were religiously set at 3.5gpl and stopped about 1.2gpl. And say it starts regen and drops only a few gpl before I stop engine, as soon as I start back up its instantly back to regen. It's determined to drop a set amount when triggered by miles. Just an observation I found interesting.

 

I have been tracking regens since the truck was new. I have a regen that has happened every 600 miles since the truck was new. This regen will cut in even if my DPF is less then 15 percent full and I am towing the only thing that matters is the 600 mile mark. I think this regen is a little longer then the other that are produced by back pressure. I don't see too many passive regens when empty. Its interesting that yours is set at 450 miles.

 

This is a good sign that you're using the truck the way it was designed. Work hard and clean as programmed. Am I remembering correctly that you have a newer truck? The older models did run more miles before a mandatory active regen.

 

I am having the same experience with my regens starting between 500 and 600 miles when they had been at about 350 miles. I installed a tow tune about the same time so figured it was that.

 

Thing is that there is zero difference from the way I drive during the summer where the jackhammer regens occur. Still about 900 miles a week and towing. Even when I towed in 80 degree weather with egt temps 650, passive regen never occurred. It's like this engine makes more soot in warmer weather than can be dealt with by passive regen. Plus my average miles between regen in summer was 150ish.
I'm using my trip and will keep track of miles in between. I reset just as the status light kicks off on my cts.

 

I just took a 5,000 mile trip, empty outbound, pulling a 7,000# RV back. It actively regened every 500 miles, even if the soot percentage was in the 10% range (in which case it would indicate ~-15% when it was done. Outside temps varied from 10-30 degrees. Exhaust temps were typically 400-500 degrees empty, 600-700 degrees loaded, and 1,100-1,200 degrees in regen. With the low outside temps it seemed to take a long time for sensor #1 to get to 1,100 degrees - #2-4 would be there for several minutes before #1.

Sidebar: my truck had 10,000 miles when I left. It seems to run smoother and with noticeably more power since I've been back. Still breaking in, I guess. (19-21 mpg empty, 9-11 mpg pulling the 7,000# RV, part of the time with a 20+ mph side wind)

 

This is exactly what I've been seeing since I started monitoring the PIDs. I watch the exhaust manifold temp, the pre-dpf and the post dpf temps. The actual cleaning only occurs when the post dpf temp is over 500 degrees. You can watch the SOOT % drop immediately after a good 10 second full throttle on-ramp. It's very predicable that whatever the soot percentage, you can manually decrease it 5 - 10% by heavy throttle acceleration. It's a combination of temperature and pressure. When the turbo is at 20 psi and the temps are over 500, passive cleaning is taking place.

 

Actually it when the temps exceed 572° F when passive regen takes place

 

Assuming a passive regen is indicated by soot levels dropping while driving, I sometimes see that with EGT4 in the upper 400s. My active regens are every 500 miles, but were at about 350 prior to winter and the tow tune. I think passive regens could also be indicated by the soot level failing to rise.

 

Well there you go, 572 it is. Which is hard to get to when the truck is empty and toolin' around town but easy to maintain when pulling a trailer. It's just confirmation of the old bird wisdom which says these diesel engines prefer to work hard and run hot.

 

So if a "passive regen" is "passive", how do you know it is happening?

I don't bother following my regens, don't really see a need to, but I do see on my Edge monitor that the truck has averaged about 450 miles between regens.

 

There really is no need to monitor them, other than just for interest sake. The truck takes care of itself.

You can tell the passive regen is happening when you watch the soot % drop on the DPF PID. Soot is burning out of the DPF at 572 degrees without having to actively inject diesel fuel to heat it up.

 

I started monitoring regens after some misguided soul told me that I would choke my DPF if I tuned without deleting. Turned out he was 180 degrees off the mark as I have fewer regens tuned.
My CTS told me that I was averaging over 800 miles between regens so I replaced that PID with something more useful and accurate.

 

I convinced as of this evening that Ford modified the programming on the latest emissions update this past summer as to when an active regeneration will begin due to miles (lower value than before). I have seen more of my recent regenerations begin due to miles than need this winter, except for the CEL event a week or two ago where things apparently were plugged up. This is different behavior than previous winters and I have not hooked up to a trailer in four weeks. Regenerations were slightly less often in previous winters compared to summer but it would still begin based on soot GPL. Not a concern, just interesting results after five years.

 

Are there any tuners that let you set the miles between miles-based active regen?