bad gas milage, please help

gotchopsticks · Aug 2, 2005

i am a proud owner of an 02 gt. so far the mods i have are mustangtuning o/r x-pipe, flow master 2 chamber, K&N, Steeda Pullys, Tri-ax, Steeda sport springs, and a DiabloSport tune. this last tank, i put in 13.5 gallons of regular, and i drove slow as possible; shifting at or before 2k, driving 65-70mph on the fwy, no racing, hardly ever getting on it, and i only got 240 miles. that equals out to 17.7 mpg. most of the driving was on the fwy as well. i can smell that my engine is running a little rich, but with the Predator i turned on the MIL eliminator option. i was listening to my engine idle today, and it sounds like there is a misfire, and even at 1k rpm i can here it. the motor only has 41k on it. sorry for the length, any help will be greatly appreciated

mrvax · Aug 2, 2005

Maybe you need to change or re-gap your spark plugs.
Check to ensure your K&N was cleaned & re-oiled properly, lest it clog your MAF.
What is your a/f ratio after the tune? It should be about 13:1. You may need a dyno with a sniffer to check this out properly. If your a/c was off, I'd think you should see 23-25 mpg on the highway with your mods.

gotchopsticks · Aug 2, 2005

what spark plugs are recommended? what gap should they be at? thanks

Seraphitia102 · Aug 2, 2005

gotchopsticks said:
and a DiabloSport tune. this last tank, i put in 13.5 gallons of regular, and i drove slow as possible; shifting at or before 2k, driving 65-70mph on the fwy, no racing, hardly ever getting on it, and i only got 240 miles. that equals out to 17.7 mpg.

First of all, since you have a Diablosport tune, you shouldn't be using regular fuel. You should be using premium unless you got a custom tune that is made for regular fuel. Then again, your power gains coming from the tune is part of adding premium fuel. Aren't you pinging with regular?

As for your 17.7mpg, you're better than me. I'm hardly at WOT and I get 15.X mpg on average. My mods are only bolt-ons and a Superchips tune. With some highway, I get about 17.X as well, same as you.

When I was driving all highway to San Francisco from Los Angeles, I got 25mpg. That was with no traffic running at 75-85mph.

forpit2000gt · Aug 2, 2005

if you are running stock plugs they are platinums, if you replace with platinums, you do not need to gap, they are pre gapped.
if you change to a copper plug, motorcraft AWSF32C, Autolite 764,NGK tr55, copper plugs gapped between .050-.055, I use .053
change the fuel filter and clean or replace air filter.
there are other plugs, Champion, Denso( to expensive for NA)

gotchopsticks · Aug 2, 2005

the tune i am using is the one that comes on the module, but i am trying to find the parts to download the new tune. how can i make my gas milage better? thanks again

forpit2000gt · Aug 3, 2005

gotchopsticks said:
the tune i am using is the one that comes on the module, but i am trying to find the parts to download the new tune. how can i make my gas milage better? thanks again

tune up car and then use programmer to take away power and set up for economy. it takes more fuel to make more power. there are other variables.

timeless2 · Aug 3, 2005

I'm getting around 25mpg on average.

jstreet0204 · Aug 3, 2005

gotchopsticks said:
the tune i am using is the one that comes on the module, but i am trying to find the parts to download the new tune. how can i make my gas milage better? thanks again

Most tunes will not effect hwy driving, since they deal with WOT parameters. If you are keeping your foot out of it, then the tune likely has little to do with bad gas mileage, other than the fact most require you to run higher octane which will sometimes cause a drop in mileage. Check you Air filter, plugs, pcv valve, etc. You may also try cleaning the MAF sensor.

sgarlic · Aug 3, 2005

Be happy you aren't me, getting 10 mpg in my stock '04.

Mossberg · Aug 3, 2005

I got 24 mpg in mixed city and hwy driving last tank. This was mostly highway though compared to city. My next tank will be more city for comparison.

BooWFO · Aug 3, 2005

I got better than that after my 4.10's. maybe the motor is detecting a knock with the lower octane and pouring in fuel to prevent it.
Are you sure someone didn't "borrow" some gas?
Now if I could just get my MPG back up with these stupid tr-6's.

DCjuggalo · Aug 3, 2005

gotchopsticks said:
i am a proud owner of an 02 gt. so far the mods i have are mustangtuning o/r x-pipe, flow master 2 chamber, K&N, Steeda Pullys, Tri-ax, Steeda sport springs, and a DiabloSport tune. this last tank, i put in 13.5 gallons of regular, and i drove slow as possible; shifting at or before 2k, driving 65-70mph on the fwy, no racing, hardly ever getting on it, and i only got 240 miles. that equals out to 17.7 mpg. most of the driving was on the fwy as well. i can smell that my engine is running a little rich, but with the Predator i turned on the MIL eliminator option. i was listening to my engine idle today, and it sounds like there is a misfire, and even at 1k rpm i can here it. the motor only has 41k on it. sorry for the length, any help will be greatly appreciated

u got any sound clips of the mustangtuning xpipe and flowmasters?
i ordered the same xpipe and already have flowmasters

PULMEOVR · Aug 3, 2005

Wow, your mileage is pretty bad. I got 26 mpg last fill up. That was say 70% highway and 30% city. I also got on it a couple times (passing people and such).

Do/check: Fuel filter, plugs, air filter, tire pressure, a/f, proper gas, tune.

Matt

gotchopsticks · Aug 5, 2005

yesterday i took the predator tune off the car and set it back to the factory tune, and i noticed a huge difference in the gas milage. the power is noticably less, but its a reasonable sacrafice for me. now i think i need to replace my plugs because i can hear a misfire...

Seraphitia102 · Aug 5, 2005

I used to clock in at 15.X mpg with the stock tune, and when I changed to the superchips tune, I still get around 15.X, but it is more mileage because I accelerate the car a lot more than what I had with the stock tune. With the stock tune, I wasn't able to get power from the tune and neither could I reach 6,000rpms with it. Now I can hit red line with the superchips performance tune and still manage to get 15.X mpg. It's certainly not "good" mileage, but it's better than what I had before.

BaconBits · Aug 5, 2005

Tuners can kill your gas mileage. I go an XCalibrator 2 with an aggressive premium gas tune, and my MPG dropped by 4-5!! I went from 24 to 19-20. My car is a daily driver and not only was the cost of premium gas killing me, but to get 5 less MPG really sucked! I just returned my tune back to stock and got under drive pulley's. We'll see what a difference that makes. I can live without the 10-15whp from the tune.

tomustang · Aug 5, 2005

How long were you experencing this bad gas mileage? when was the last oil/filter change?

forpit2000gt · Aug 5, 2005

why do you mod your car for more hp and then complain about mileage. With some tuning you will have morepower without a big change, then at a certain level the mileage goes away because it takes more fuel to make more power. If you want mileage , get a tune or chip that has a few settings, one for mileage and one for n/a performance and one for maybe nitrous setup.

Stang|ess · Aug 5, 2005

Do you use a lot of AC? I noticed that when I would use the ac on the 1 or 2 setting, for about 30 minutes a day, id get about 22-23 mpg. But it's just so damn hot now, so Im running ac all the time, and it dropped me down to 18.

bad gas milage, please help

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