07 LMM Fuel question

[whiskey tango]

Hello, my name is Lee. I am new to this forum and trying to learn about EFI Live and all its amazingness, LOL! I have an 07.5 LMM 2500HD. It has a diamond eye 4 inch turbo back exhaust I just installed. I also installed the DSP5 switch (pretty straight forward). I have used EFI Live to download the stock tune file and have sent it via email to the person (syntheticmotorsports.com). I have not received my five tunes back yet, but since the new exhaust install I have noticed that my mileage is around 10-12 MPG. I have a six inch skyjacker lift with 35 inch tires and 17 inch wheels. Before the exhaust install I was getting pretty solid 13-14 on 20 inch wheels with 32 inch tires.

My question is why the difference in mileage now after the exhaust install. I removed the old DPF, so should I not be seeing better "numbers"? I realize that my lift and tires will suffer the mileage some but not this much right? Perhaps it is due to not having the tunes back yet from the dealer? Or could this be due to the fact that I am still running the stock intake? I have a banks intake I could put on but am hesitant due to the last time I had it on, I was getting a MAF code quite often. I also beleive that the MAF code was due to the extreme cold temps here in Alaska (-20 to -50) and the fact that it is an oil based filter which I am told will gum up the MAF sensor sometimes.

Sorry for the lengthy post but I figure the more info you have the quicker my issue can be addressed. By the way I love this truck and know that EFI Live will make me love it even more. Thanks for any assistance you guys can offer too.

P.S. I do not have any guages yet but they are on the list as I know that they are very important to have. (boost and EGT) coming soon.

[Brian1]

So you deleted the DPF and not changed any programming yet? Mileage decreased from doing this?
I would suspect the truck is doing things since it still believes the DPF system should still be there.
As if you get better mileage with a tune and DPF delete that is a gamble. All these trucks run different. The more one increases the tune power one may not gain in mileage. All in the tuning that can make a difference. I would not bother with the Banks intake. Stock intake is more than enough for a stock turbo and injector with tuning maxed out to the most a stock duramax can do. Of course the Allison will not last in a case like this for long.

Brian

[whiskey tango]

So you deleted the DPF and not changed any programming yet? Mileage decreased from doing this?
I would suspect the truck is doing things since it still believes the DPF system should still be there.
As if you get better mileage with a tune and DPF delete that is a gamble. All these trucks run different. The more one increases the tune power one may not gain in mileage. All in the tuning that can make a difference. I would not bother with the Banks intake. Stock intake is more than enough for a stock turbo and injector with tuning maxed out to the most a stock duramax can do. Of course the Allison will not last in a case like this for long.

Brian

Yeah, I figured that the truck still thinks the DPF is still there. I had to run it like that due to not having my tunes back from the dealer. I now have them and will be loading them very soon (as in a day or so). What exactly did you mean by the "Allison will not last in a case like this for long", Brian? Are you specifically speaking about my tires and lift or where you talking about the DPF removal part?

[Boost]

I think he meant that the power a good tune with exhaust is able to produce will much more rapdly wear down and eventually destroy the Allison. Some trucks with 5-600 hp drive right through the stock torque converter, others only slip occasionally especially in the higher gears, and /or bang into gears and go into limp mode. Most hold up very well considering, and with good tuning and light driving it may last with minimal trouble for over 100k miles. All this is my opinion / experience. You should do an upgrade torque converter and a Transgo or similar shift kit, if not an all out built Ally. ($$$).

As far as the DPF removed with the stock tune, I am thinking extremely bad fuel economy and heavy smoke is the best case scenario, there are stories of going into limp mode and rumors of cathcing on fire..... get it tuned. Good luck with your nice truck.

[whiskey tango]

Thank you for the information and recommendations. I made a few phone calls, and I will be getting a new set of tunes which should alleviate the immediate issues as well as saving up for the trans upgrades. For now, the truck is parked.... Thank you very much for the posts.