LML Exhaust Regeneration

[JohnnyR]

Whenever the exhaust regen occurs on my 2012 3500HD Duramax, I have noticed 2 things. One, idle speed increases about 200 RPM; and two, fuel mileage steadilly decreases for the 20 minutes or so regen occurs. Running empty, fuel mileage will ultimately be reduced 2 to 3 mpg. Will regain perhaps 1 mpg (at best) of that loss before next fillup. Is there any way to reduce that mileage impact?

[More Power]

As soot builds in the DPF, exhaust restriction increases. The rate at which soot accumulates depends on several factors, with exhaust temperature being one of the bigger factors.

Those who tow or run at freeway speeds for longer periods see fewer active regenerations. While towing, exhaust temperature could be high enough that the soot is being consumed at nearly the same rate as it builds in the filter.

Cooler temperatures that occur during the winter months compound the problem - if you can call it that. If you know that you'll be driving around town or locally in cold/cool temperatures, you might be better off driving some other vehicle, if one is available. The only downside to driving a DPF -equipped diesel pickup during such times is a hit to fuel economy because of the active exhaust system regenerations.

[JohnnyR]

Is there any kind of notice given by the DIC when a regen is occurring? I have not seen one or found one. Just noticed the mileage dropping or idle speed being higher. Am I missing something? Think I read that Ford tells you.

[justlkn]

I don't think it tells you anywhere. The only way I know is the elevated idle and the motor actually sounds a little different during acceleration.

[Kennedy]

It only tells you if it's PO'd. It nags you to drive if you let it get loaded by excessive idling etc. Essentially if it gets too much soot load it nags you to drive in order to do a proper regen.

You can often smell at the rear of the truck when it's in regen also.

[DieselTom]

It only tells you if it's PO'd. It nags you to drive if you let it get loaded by excessive idling etc. Essentially if it gets too much soot load it nags you to drive in order to do a proper regen.

You can often smell at the rear of the truck when it's in regen also.

Hi; I'm new to this site, and I just bought a double wheeler chevy. Could You please explain to me what are You talking about, when You say regen, and how to do it, or the engine will do it automatically?
Thanks; DieselTom

[Kennedy]

I've been working on "emissions intact" tuning for the LML and have been having pretty good success so far with MPG, responsiveness, a good bit of power on demand, PLUS I had a pretty decent run between regens during unloaded highway driving.

Been monitoring the regeneration and need to do some studying as to the triggers as last regen was long on miles, but at a low soot accumulation.

[cabletech]

I think it starts at 700 miles or 44 grams of soot (at least on my LML).

Jay

[Kennedy]

I believe from what I have been reading is that there is a 700 mile component to this as well as differential pressure/soot load.

Mine was doing mid 300's but last one was at 700 and only 24g soot load at the time it started. It finished in 34 miles but dropped the DIC MPG very little then started to recover quite quickly.

[cabletech]

My truck regens between 400 and 700 miles on summer fuel. It drops with winter fuel. Here in MN, summer diesel is all B20 which may help with longer times between regens. Winter fuel is B4. The 700 miles bugs me. It a total waste of fuel to go into regen just because I went 700 miles since the last one. I can actually watch the soot load drop on it's own when I'm towing heavy (no need for active regen).

I would really like to have my truck reprogramed, but can't afford to loose the warranty. I don't need any more power, but it would be nice to get a little better mileage. I may think a little different after the truck get closer to the end of the warranty.

Jay

[Mark Rinker]

I put 120K miles on my last 2009 LMM, only had it bother me about a regen once that I recall.

Most of the time they must have happened while towing, and since my average MPG loaded/unloaded hovered in the 12s, it wasn't really noticable.

The more you tow, I guess the less of an issue the DPF is. I was amazed at how clean the tailpipe remained over time...basically ZERO soot accumulation, indicating that not much makes its way out.

[Frys6971]

I believe from what I have been reading is that there is a 700 mile component to this as well as differential pressure/soot load.

Mine was doing mid 300's but last one was at 700 and only 24g soot load at the time it started. It finished in 34 miles but dropped the DIC MPG very little then started to recover quite quickly.

How do you find out your soot load, does it say in the DIC?

[Kennedy]

Soot load is monitored in the scan data.

I encourage my tuning customers to start with the Edge Insight: http://www.kennedydiesel.com/detail.cfm?ID=673


The Insight is used to monitor the soot load among other things. It is also a useful coach in that when you see it beginning the regen mode you can drive accordingly. In my case knowing that the regen is coming every 700 miles like clockwork is also helpful. Whenever possible I try to plan to be on the highway when this comes around.