i was thinking about tuning on the LMMs for fuel economy and had some thoughts i wanted to share and get other peoples thoughts.

typically when we tune our dmaxes for fuel economy we increase the timing, increase the fuel pressure, change the boost, maybe change the pilot, etc.

my thought is what effect does this have on emissions????:rolleyes: ?????

if it causes the DPF to "fill up" quicker it should go in to regeneration quicker!!!

it seems the LMMs get decent mileage except for the fact that it dumps fuel when it goes in to the regeneration.

so will these same type of changes have a negative effect on mileage since it will go in to regeneration???????

any thoughts would be appreciated :)

Robert,

To answer your questions I think it's important to differentiate between 'emissions' types first.

Particulate (DPM) emissions are different than NOx emissions. Although they both travel through your DPF, only the particulate emissions cause clogging and increased regeneration cycles. You will be increasing your DPM emissions anytime you make changes that increase your soot production.

NOx emissions are where we as tuners have room to increase our fuel economy without worrying about regen cycles or similar side effects (except global air pollution). NOx emissions are increased when we increase timing or increase the combustion temperature in the cyclinder. If you want low NOx emissions consider H2O injection to lower combustion temps.

Moral of the story: If you want to keep your DPF happy and increase your fuel economy, increase your injection timing and even your fuel tables, but keep it clean. Soot is the enemy as long as the DPF is on your truck.

Hope this helps,

Nick

so basically when tuning the LMMs we are going to try to build the perfect smokeless tune regardless of the DPF????

basically.

unless you delete or bypass your DPF.

basically.

unless you delete or bypass your DPF.

that will come soon enough. just want to wait untill a few more people to succesfully delete the DPF. and see what efilive has in teh works for the dpf

so what kinda tuning adjustments will increase the particulate matter??

seems that the only one that would have a major effect is increasing the actual amount of fuel requested.

(on a side note it seems that my reducing timing for NOx reductions would increase the smoke or particulate matter)

(on a side note it seems that my reducing timing for NOx reductions would increase the smoke or particulate matter)

Bingo :)

Fuel pressure would also play a minor role, but you nailed it for the most part.

Good topic.

I've been messing around getting pretty good results. I just don't know how much timing is too much. In comparison to the lly's and the LBZ's, it seems like the LMM has alot more timing stock. A good amount of the stock map shows up in EFI Live in red. How much is too much?

Pushed2DMax,

Here's a link to some very good timing discussion, you'll notice that the right timing has a lot to do with how much fuel you're adding -> http://www.dieselplace.com/forum/showthread.php?t=98656


Don't be threatened by the 'Red', it's only there to show contrast between different values on the table. If you changed all of your values to 40* (a rediculously high number) the whole table would go yellow.