MacaveliMC

I have a 2007 2500 Mega Cab, with EGR deletes and a turbo back exhaust that includes only a muffler.

I just bought it this January. I changed the oil, topped off the power steering fluid, and changed the oil, air, and fuel filters. I found out the mechanic who worked on it had to get a tuner to tune it, with EFI Live. They installed a 5 point switch with the following tunes:

1. +15hp stock-ish crappy tune
2. +30hp
3. +60hp
4. +120hp
5. +180hp

Once I found this out, it was recommended to me to run on 3, 4, or 5 for better fuel mileage. I have no interest in "hot rodding", or runnin' wild, I need this truck to last for a very long time so I drive relatively conservatively, barely ever pushing it past 50% throttle, and keeping the truck under 2k RPMs.

I was told I should get around 20mpg, which I kinda scoffed at. So I ran a couple tanks of gas on setting 4. I got about 15mpg.

Then I switch to setting 5, and it looks like I may be getting around 1mpg better.

I told this to a few friends who know diesels much better than me, and they were shocked I wasn't getting much better MPG. They claim I should be at LEAST 18-20.

I called the mechanic back. He said yes, it sounds low, I should be getting 18-20.

Now I bring it to this forum of vast knowledge and experience

Can anyone suggest anything that may be wrong? I was told if an injector was bad, I'd know it and that's most likely not the problem. My next step is to read boost off the OBD2, but honestly the truck doesn't "feel" like it's "gutless" as the mechanic suggested.

Here is a picture underhood.

steelblitzkrieg

They're wrong plain and simple. You might hit 19-20mpg's under optimum conditions, but realistically 15-16 highway is average, with 17-18 highway obtainable with not much difficulty. They may be reading their lie-o-meter rather than hand-calc. I don't recall my exacts but I hit 20.? coming home from 7K to sea-level while drafting a rig with a tailwind before mine was lifted.

I also would strongly urge you to not use anything above 100HP with out a built tranny.

As you can in my sig, I'm a fuel saver, not a hot rodder. Those are lifetime MPG's. I was at 17.? before the lift.

MacaveliMC

Hmmm, good to know. I called the mechanic back with a little more info, and he said his dad, who has the same truck, just told him he struggles to get 18 in reality. So, sounds like it makes sense.

So nothing above 100HP? Even driving like granny? I thought I read somewhere that these tunes also take into account the torque rating of the trans and don't let you push that envelope? I could be wrong...

Edit: Probably should of noted I have the manual trans.....if it makes any difference.

steelblitzkrieg

Typically on a 100hp tune you're going to see an increase of around 200ft-lbs torque. I have an auto so I can't speak intelligently on the sticks capabilities but I know most modify them when increasing power above 100/200.

xcc_rider

There's lots of things that affect mileage. You don't say if you have an auto or manual trans, diff ratio (you can get your build spec sheet from the Dodge owners website), tire size, lift, 4x4 or even if you're driving with a cab over camper on it.

Realistically with the truck in my sig line I can get over 20 mpg hiway empty on flat land and almost 12 mpg towing 7300 lbs in similar conditions on a 70hp tune and moderate advanced injector timing.

That being said, there's others with more mpg's and less mpg's. It all depends on the truck and the right foot.

MacaveliMC

Good points! I did actually mention in my second post that it's a manual. But beyond that, everything is stock as far as I know. I was wondering if the last owner made a modification to the rear end gearing, but I don't know how to tell without tearing it apart and counting teeth lol

Beyond that, it's just the truck, stock for all I know. No cab on the bed, no lift or different tires. It is a 4x4 so obviously that's a bit more weight. No cold air intake or anything.

I was not surprised personally by the gas mileage I was getting, especially with the size of the truck, but this is my first ever diesel and I don't really know what to expect.

MacaveliMC

Here's some pics too! I do think it looks pretty cool but probably not to all these guys on here with lifted trucks, big wheels, and smoke pouring out the back hahaha

mega-engr

Nice truck! Congratulations. My truck is similar to yours being 4x4 megacab, but I have an auto trans. Regarding MPG, I'd say 80% has to do with the pedal operator. Like XCC described well, I might get up to 20 MPG with optimal road/driving conditions (using it like a car). When I tow, I get about 10 to 11 MPG. I have a tuner for the minimal smog deletes set for a small to modest power increase only. Realistically, with mixed daily driving, I get around 17 to 18 MPG at best.

MacaveliMC

Thanks! Good to know I have something to compare with. I've been driving around on the +120HP and now the +180HP and 98% of the time I'm trying my level best to take it easy. I probably use 20-40% throttle, and shift below 2k. When I tow I'm definitely gonna put it back down to the +30HP or +60HP because, with heavy loads at both ends, obviously that's when the middle breaks. But my hope is I'll be OK driving around on the higher HP settings conservatively because I get better gas mileage the higher I go!

mega-engr

My understanding is that the clutch is the weak spot and has had issue with stock power even. So that seems like a decent "fuse" to keep you from over powering the rest. However, that can always be upgraded. Yes, just because you have a capable +180 HP doesn't mean you have to use it.