this isn't a rant on "sh*tty gas mileage", it just seems like something doesn't add up. i have a v8, i knew gas mileage wasn't an included option, and mpg on the sitcker says 12-18. i got mine when it had 23k on it, and i rolled 64k miles the other day.

so i've had my bully dog for a bit now, and i've had my tires for about the same time. lift i did back in april.

i get the summer vs winter fuel mixtures. when i was stock i could get a good 18-19 hwy in the winter, even driving pretty aggressive. for city i'd get 16-17mpg. in the summer those numbers would drop because of the summer mix, hotter temps, ac running all the time, and so on. i'd get about 12-13 city and around 17 hwy.

then i got the lift, heavier tires, intake and the bully dog pretty much over the summer. i've had the bully dog on the premium tune, and have been running 91/93 octane. my mpg's in the city went to 11-12, and that was grandma driving it. hwy wasn't much better coming in at around 14. even with an octane booster i still couldn't get above my regular marks. i just attributed it to the hotter air and summer mix.

i did a ~150mi round trip up to the choctaw casino the other night, all hwy. it was about 50-60F outside, so no ac. no real traffic and only some very mild hills. i used cruise control and set it to 70-75 (speed reading adjusted for bigger tires via bully dog). i topped out at 14.5mpg. in the past this type of test would yield me a good 1-2mpg over my 'regular' hwy driving style, especially when combined with cooler temps and lack of ac usage.

now here's what i don't get. i changed the tune to 'regular', but put another tank of premium in. i then did another test that was more hilly, had city driving in it (and about 10 stop lights), and included some AC usage. i came in at 15.5. 15.5 for mixed usage! wtf! after the test i continued through the testing using my 'regular' style driving and still came in at 13.5 overall.

my idle seems fine and always hangs around 600-650rpms. the engine seems to run smooth, although the upshifts are just starting to occasionally hang for an extra second, and if i manually downshift to 2nd from 3rd i sometimes get a 'bump' when it engages. tomorrow i'm planning on changing the trans fluid, and i had the diffs and xfer case done about 10k miles ago.

i'm also running about 44psi in the bfgs, as when i was running 35psi i was getting alot more wear on the outsides rather than the center (after about 2500 miles i had 16/32 in the middle and 15/32 on both the sides). since airing up i'm at 15/32 all around (3500 miles, will be rotating tomorrow as well).

anyone else with a v8 & bully dog experiencing this? while i do LOVE the bump in performance, i'm not sure that on a daily basis i want to sacrifice 3-4mpg. i mean i'll give it a few more weeks just to make sure it's not the summer mix that's killing me, but i just can't imagine the fuel being the only thing.

Is this per tank, or per what the MPG reading is giving you?

Maybe it's different in California, but "winter" fuel has oxegenates in it (Ethanol, MTBE, etc) which *decrease* mileage, not the other way around.

But anyway, a clear test would be with your ECU box connected and then taken out, driving on the same repeatable route in roughly the same timeframe and weather.

I'm going to be putting a Volant intake on my V8 this weekend and will do some careful power and MPG tests to see how it does...

nmex - just using the mpg on the display. it used to be within .5mpg when i was stock, but now it's ~1mpg less than using the pencil and paper method. but that could be argued that i don't fill up exactly to the same mark every time, etc, etc...

well in texas we only have the 'air friendly' version in the summer. plus if you go out to the sticks, they have the gas that doesn't have 10% ethanol in it, which gives a good 1-2mpg back.

i've lived in texas all my life, and i've always gotten 2-4mpg better in winter vs summer, including back when i had my acura tl.

and i was always under the impression that oxegneators helped mpgs, not decreased. or maybe here in texas they do, and in cali they don't, since your air quality is so crappy

yeah i have more testing slated. although adding ~100lbs of rock sliders sure isn't going to help

Your real MPG vs. computer should be way off due to your tires. With our 285s having a 7% longer circumference, that not only means your speedo reads 7% low (70MPH is actually 73), but also you're really travelling 7% further for each of those miles the MPG gauge calculates. Test it against some GPS sometime and you'll see how far off it can be...

But anyway, none of that has anything to do with your current situation, since your before & after tests of the ECU box are with the same tires

Now that you've already fallen off the deep end, might as well make it worth and swap some 3.36's.

NmexMAX wrote:Now that you've already fallen off the deep end, might as well make it worth and swap some 3.36's.

oh i would LOVE to do that. gotta buy a house first though. then after that, save for week+ trip to germany, theeeeeennnn i can do gears

I've been considering the bullydog tuner to try and impove the mgp. I have a 2010 4.0l 4wd and average 11-12mpg in town and on the highway I've never gotten better than 17.5...I was quite shocked with how atrocious the mpgs are. Any suggestions?

special_K wrote:I've been considering the bullydog tuner to try and impove the mgp. I have a 2010 4.0l 4wd and average 11-12mpg in town and on the highway I've never gotten better than 17.5...I was quite shocked with how atrocious the mpgs are. Any suggestions?

well you might have better luck, my buddy with a frontier put his in and got a good 1-2mpg better, with the increased hp. his is 4L 4x4.

doctahjones wrote:

special_K wrote:I've been considering the bullydog tuner to try and impove the mgp. I have a 2010 4.0l 4wd and average 11-12mpg in town and on the highway I've never gotten better than 17.5...I was quite shocked with how atrocious the mpgs are. Any suggestions?

well you might have better luck, my buddy with a frontier put his in and got a good 1-2mpg better, with the increased hp. his is 4L 4x4.

I may end up ordering one...or you can sell me yours when you take it off

special_K wrote: I may end up ordering one...or you can sell me yours when you take it off

haha, fat chance. i'm not giving up on this thing, just trying to get the most out of it

doctahjones wrote:

special_K wrote: I may end up ordering one...or you can sell me yours when you take it off

haha, fat chance. i'm not giving up on this thing, just trying to get the most out of it

I had a mustang before this pathfinder. I took it to Arlington and had headers, mid pipe, mufflers, cai and a custom dunno tune...I got 19mpg in town before the work....12 after lol!

special_K wrote:I've been considering the bullydog tuner to try and impove the mgp. I have a 2010 4.0l 4wd and average 11-12mpg in town and on the highway I've never gotten better than 17.5...I was quite shocked with how atrocious the mpgs are. Any suggestions?

You must be a little heavier on the pedal than me. With the same drivetrain setup I'm currently at 15.5 and that includes mostly around town (my commute is 3 miles) plus a few miles on the highway. I haven't reset the mpg monitor in maybe 4-5 tanks. I got 18 with the load as in my picture to the left cruising at 75. I never expected the path to be economical, but I have been pleasantly surprised that I can actually get pretty much what the official rating is.

leadpig wrote:

special_K wrote:I've been considering the bullydog tuner to try and impove the mgp. I have a 2010 4.0l 4wd and average 11-12mpg in town and on the highway I've never gotten better than 17.5...I was quite shocked with how atrocious the mpgs are. Any suggestions?

You must be a little heavier on the pedal than me. With the same drivetrain setup I'm currently at 15.5 and that includes mostly around town (my commute is 3 miles) plus a few miles on the highway. I haven't reset the mpg monitor in maybe 4-5 tanks. I got 18 with the load as in my picture to the left cruising at 75. I never expected the path to be economical, but I have been pleasantly surprised that I can actually get pretty much what the official rating is.

I drive pretty slow...if I don't it fronds down to single digits. I've never seen 15mpg average in town. I'm starting to think something's wrong with it

Had to make a quick trip out of town before work today. Got a whopping 15.9!