Just did a big trip, 2400 miles/4 days IL-TX-IL. Ran the FORScan Lite app on my iPhone and using a WiFi adapter to connect the truck to it. Monitoring my EGT's on way down there, I noticed that my unloaded EGT's were all running under 600F on the drive down. My Regens were happening around every 500 miles or so. Pretty normal.

On the drive back, pulling a 6 x 12 UHaul trailer that was loaded up, but not excessively full, my EGT's ran in the high 600's to low 700's. Now it has been my understanding from reading other threads here on the forum, that with those EGT's I should have had enough passive regen happening to either minimize or not have Regen's at all. Instead, I was having Active Regen's happen and happen more often than when unloaded. At between 350-400 miles.

So, my question is, at what EGT's do the passive Regen occur at? Because, it sure isn't just above 600F as I've read in other post's!


Dave

2016 CCLWB F350 SR

 

It is my guess that at the bottom of the Passive Regen temperature scale that you might be making more soot then the truck can burn, say at 600 degrees and different loads on the engine. In short, 600 degrees isn't written to stone.

 

I saw passive regens happen more in the mid 700's when I towed a 5'r to west cost from alabama last year. In the mnts they would go higher on EGT3&4.

 

When towing my fiver down to AZ last fall, I was going into regen every 150-200 miles... It was very perplexing ..... One other odd thing though was the fact that the regens really did not affect my fuel economy by more than .1 MPG if at all... 7.2 - 8.2 MPG was what I was getting the whole trip..

 

IMHO, If your foot is in it more because of the extra weight you will produce soot. Look at how an bobtail rig takes off vs. one loaded down...

Plus you probably are not really producing enough heat to do a passive regen. Painted Horse has all sorts of data on passive regens. Maybe he will chime in, I don't want to steal his 'thunder'.

 

Which EGTs were you looking at? Seems like EGT4 is the only one that matters, often it runs lower than the others unless there is excess fuel (like during a regen).

 

I watch EGT 3 and EGT 4.

Generally they are close to same value with EGT 4 being the highest.

 

Makes sense Dak...

My EGT4 was between 500 & 800 cruising and not in Regen. When in Regen it would hover just under 1200 most the time...
The other odd thing was the GPL would barely get above 1.0 and it would go into Regen.

Trailer and truck weighed in at 28k..

 

up around 700 and mine will be passive.

When ever I pull my 5er I never regen. I am heavy.

Other stuff it will regen.

 

The way I see it, burn more fuel-make more soot.

I tow almost all the time and for lots of miles and I know when I'm loaded heavy and fighting headwinds I'm burning fuel and making more soot. My regen events usually happen between 500-700 miles when cruising interstates. I know that driving solo without a trailer my regens happen a little bit less often but not much.

What I see with my truck is that it doesn't do passive regeneration hardly ever. I had the dpf% screen activated approx. 10,000 miles ago and not once have I ever seen it drop down unless it is during an active regen cycle. Maybe it's not supposed to but logically if the passive regen is happening one would think that the screen would show it dropping in percentage full.

So, count me in the crowd that thinks passive regen doesn't really happen, at least not on my truck.

 

Yes my screen will show the soot percentage drop when heavy towing.
I am up around 16K for the trailer. I think you are much less in the weight dept?

 

Yea, I'm between 8-12k all the time. Prob right at 10k majority of time but my trailers are all 10' tall. I haven't looked to see what my egt is cruising but I'm sure it's fairly high. My mpg averages are 9.

 

I get no passive regen in the summer. Egt's in the mid 600's-700 and nothing, gpl's increase, don't even maintain. In the winter when i'm in the 600's you can watch the gpl's drop.

 

But only in regen? On my truck, 3 and 4 are normally lower, except during regen.

I have the 3rd dash screen and have never seen it go down except in regen. It does not track very well what you see on the OBD information. I believe the 3rd dash screen is programmed only to go up (though it may dwell in one place for awhile) to keep user confusion down. Kinda like the "oil pressure gage".

You guys who say you are having passive regen. How do you know? Many of the OBD reported parameters are actually inferred from operating conditions, not measured. The only two that seem to be measured are (in 15&16) the DPF comb sensor, and backpressure differential. I'm not sure the former is reported directly on OBD. The latter is, but not with much precision. Are you just assuming that if the temps are high enough it is happening? The g/pl load reported will go up and down a little over a short time, even if temps are clearly too low for passive regen. So I am wondering how you know passive regen is happening.

 

I can watch the gpl's go down. Just as I can watch them go up in the summer with high egt temps.