[02v6staang]

So the case is that im getting horrible gas mileage. Around 80 miles to half a tank. I have replaced the fuel filter, had an injection cleaning..gas treatment. Nothing changed. I currently have full exhaust (longtubes & catted h), intake spacer, 3.73's & t-lok, sct tuner, cai. any ideas??

[2002 BLK GT]

Check your spark plugs,oil, tire pressure even if they look ok.
Aftermarket wheels? Try filling on good brand stations like Shell for ex. Are those stats from highway/city? How is the idle? Do you smell fuel when you get into the car and start it? Do you drive it hard?
Try seafoam.....

[GreenFaleen]

drive with less foot lol

[Brian147]

Originally Posted by 02v6staang So the case is that im getting horrible gas mileage. Around 80 miles to half a tank. I have replaced the fuel filter, had an injection cleaning..gas treatment. Nothing changed. I currently have full exhaust (longtubes & catted h), intake spacer, 3.73's & t-lok, sct tuner, cai. any ideas??

Are there any oxygen sensors on your setup? If so are they located in the same spot as they were factory? If so are they old or new oxygen sensors?

-If you have no sensors you will be dumping fuel
-If they are not in the same location this can cause the computer to run lean
-If they are old sensors they could be shot (they dont need a service engine code for that to happen)

[ApeXX]

I've noticed decreased gas mileage in my Mustang also... Although I have to say it certainly isn't THAT bad!

[01VBmustang]

I was getting about the same mileage lup until ast week, but i was also smelling fuel when the car was running and right after i had been driving around.

Looked at my filler neck for the gas tank and there was a leak in it.

Got it fixed and I am still on my first fillup since, 148miles and just below a half tank.

[6ER THEN I 8ER!]

ive heard that gears can cut down on gas mileage, but not by that much...

[ApeXX]

Originally Posted by 6er_w/a_Vengance ive heard that gears can cut down on gas mileage, but not by that much...

From what I understand 3.73's and 4.10's both hurt gas mileage to varying degrees. Since you'll be highway cruising at higher RPM's, your bound to lose some gas mileage regardless of what gears you install. It's my understanding that 4.10's hurt the most, seeing as they are steeper gears.

[01VBmustang]

On a 3-3.5 hour trip from virginia beach to JMU doing 70-80 the whole way i got around 23 to 24 mpg. My filler neck may have been leaking a little back then, not sure, because i just got i replaced last week.

[orson250]

i have heard of people who had mpg issues after they installed the lt's. i second the motion to check the location and condition of the O2 sensors. not saying this is definitely related to the lt's, but it might be since it's aftermarket

[04mustang232]

id sea foam the engine through a vacuum line to clean your egr, and your o2's

[02v6staang]

I have drove the car with less foot. slow take offs and its stil the dame. I didnt notice the mpg loss until after my longtubes...so its definately not rly the gears. Ive done a recent tune up, so the spark plugs are good. I had it on the dyno and the a/f ratio is dead on. So i have some o2 extenders i will try Hopefully that helps.

[04mustang232]

what did you dyno at? (not to change the subject)

[getchapull]

lol it sounds like bullshit, but read the manual about good driving tips. im getting an average of 20-22 mpg in the city with good driving habits plus keeping the car well maintained