[silverbullet17]

im getting 13.8 mpg on my 1999 mustang with k&n air system and a 93 octane tune. thats terrible. i had my spark plugs changed not that long ago. what could be making my mpg suck so bad? thanks

[whitemustang02]

a lot of things, bad plug wiers, bad 02 sencer, bad tune, engin bild up / wear,
it may be one of these or a collaboration
a litlle more info may help narrow down the problom.
how many miles dose the engin have,
were did the tune come from
when was the last tune up on the car / what all was done

[whitemustang02]

also some things u can do that may help but definetaly won't hurt
sea foam ur car
and get new plug wiers i recomend MSD super conducters

[silverbullet17]

car has 118,000 miles on it. the last tune up was around june this year. i have been getting 15 regularly but have gotten 17-18 mpg a while ago. i am taking it to a mechanic for something so i'll ask him then to check it out if he can but just wanted everyone's opinion. i got the tune from bamachips. it was pinging a little so i set the timing back 2 degrees and now its fine. well it said 0-2000, 2000-4000,4000-8000 on the tuner and for each category i back it 2 degrees and it stopped the pinging.

[whitemustang02]

ya see what the machanic sais, but i would try the two things i recomended, and if thoses don't do any thing then i would try to reset it back to the stock tune, and see what that will give u. because i am getign a little over 22 wit hgeting on it hard a lot and mostly high way driving. so u have a lot u could improve

[El_Cangri]

do a tune up.

[silverbullet17]

you don't think it could my tune do you? if anything aren't those supposed to help mpg? and setting the timing 2 degrees back wouldn't mess would gas mileage would it?

[whitemustang02]

tunes arent meant to help MPG unless that is what it is desined to do they r more ment to help praformance and seeing as how u went for one with 93 octance i don't think u got the MPG freindly one

[MWWarlord]

+1 on seafoam & tuneup with new spark plug wires. It is a good idea to get new wires when you get new plugs. Also, when was the last time you cleaned your air filter? Anyway see what your mechanic says.