2011 duramax

[Eldonko]

I can't figure out why my 2011 lml goes from 14 mpg to 19 mpg, one day is good tomorrow is different..  bone stock. 105,000 miles.. Thinking of an efi live program and deleting the def

[swathdiver]

Are you fueling at the same station?

[Black02Silverado]

Might be in regen when you get the lesser mpg.

[Colossus]

Yup, your truck is doing frequent DPF regens.  Delete the DPF if you can, assuming you don't have emissions testing requirements.  or you can remove the DPF and take it somewhere for an acid bath.  either way, go chat with or search the forms over at duramaxforum.com  many over there have done DPF deletes.  I wish I could delete mine, but we have emissions testing here. 

[Eldonko]

I use the same fuel out of my bulk tank treated with hotshots,  no emissions testing here.. was thinking of going with ppei programmer,  what would be a good one? Also looking at autocal efi  live kit with exhaust, bridge, and air cleaner..

[Colossus]

Maybe someone else can chime in, as I am not good when it comes to tuners.  I hear talk about autocal EFI on the other forum.