MPG Variation..?

[bronx79]

So is it odd for my truck to only be getting 9ish to 10 MPG's in town with new plugs, new EGR valve, long tube headers, free flow exhaust, cold air intake and a 3:92 gears? And five months ago I clean the TB. I drive the truck very conservatively and still get crap!! My tires are BFG T/A 285/70/17 so I know that hurts some but I thought I would get better than what I am. Am not expecting 15 MPG but 12 or 13 isn't unreasonable is it? Just wanna here some possible reasons why mine sucks so much fuel..Thanks for any help or advise you can give me.

 

[bronx79]

So is it odd for my truck to only be getting 9ish to 10 MPG's in town with new plugs, new EGR valve, long tube headers, free flow exhaust, cold air intake and a 3:92 gears? And five months ago I clean the TB. I drive the truck very conservatively and still get crap!! My tires are BFG T/A 285/70/17 so I know that hurts some but I thought I would get better than what I am. Am not expecting 15 MPG but 12 or 13 isn't unreasonable is it? Just wanna here some possible reasons why mine sucks so much fuel..Thanks for any help or advise you can give me.

So i just read another thread about this and tires not giving the correct reading to the pcm.... the truck came with 20'' wheels but now has 17'' with what works out to be 33'' tires! so could that be giving me a false reading as well?

 

[03MopaRamman]

If your speedo is bang on your good, in winter my allround average is about 10.8.

 

[bronx79]

It reads correct at 30 cause I drive in a school zone and it matches up

 

[03MopaRamman]

Do you have a GPS, thats how I check mine then adjust the measured height in my SC a tad .25 inch usually up or down from first entry in my Superchips and do a final check at 50-60- and 70. I find if it is off it will be most off between those speeds.

Edit: You could do the Math manually based on mileage but then again that is connected to the speedo Math too!

 

[Detox]

Just for reference I have an 05 4x4 with a 5.7 as well. Truck is pretty much bone stock with 3.55 gears. Only thing i have is a K&N drop in filter and also not sure on my spark plug age. On 87 Octane "Winter Gas" i'm averaging around 10 mpg in the city and on the highway I can do around 15 mpg if i stay at 65MPH.

 

[bronx79]

Just for reference I have an 05 4x4 with a 5.7 as well. Truck is pretty much bone stock with 3.55 gears. Only thing i have is a K&N drop in filter and also not sure on my spark plug age. On 87 Octane "Winter Gas" i'm averaging around 10 mpg in the city and on the highway I can do around 15 mpg if i stay at 65MPH.

Oh okay so I didn't really even think about the awful winter gas we runnin right now. And theses tires weigh about 80lbs each so that's a big diff from what was on there.

 

[FL BOY]

Probably time to get a tuner to get the most out of your mods.

 

[bronx79]

Probably time to get a tuner to get the most out of your mods.

Couldn't agree more!!! Still not sure what to get between the intune and SC3865 but either I'm sure would be fine. I've actually tried the SC and it did little to nothing so I'm thinking diablo next.

 

[LS5DodgeRam]

If you are running on larger tires than The stock tires, but your running on the stock tire calibration, that will kill your nog meter, however you still cover about the same distance with the larger tires... I have that problem but I can't afford a programmer right now. There is another thread exactly like this one that I went into further expla.action if you want to check it out, I believe it is in the general discussion though