Bronco Forum - Full Size Ford Bronco Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
147 Posts
Discussion Starter #1
so i have no idea why my bronco is getting only 8.5 mpg. i just tuned it up ( new plugs, air filter new oil/ oil filter and all new fluids) and the other day i went to fill it up and its getting about 8.5-8.75 mpg per fill up evry 200 miles which is combined for street and freeway mpg. the only thing that is wrong with it are the tires there not the right size and the alignment is off but i dont think that would be the reason it be killing my mpg. i have no extra weight in it i took out the bench seat and the only thing i have in the cargo area is the spare tire? what can i do to improve my mpg? the last thing i want to do is sell it cause i just got it
 

·
Too poor for FSM
Joined
·
1,395 Posts
Lots of mpg threads around here to also look at. I would get that alignment worked out, that will mess it up. Stock, your only looking at 12-13 or so..

Your tires are not the right size? what size are they. If they are bigger, your speedo will be off. Mine says i get around what you get, but i have 33's and my speedo is wayy off. So filling up around 200 miles is actually like 300 (gestimation)

If your serious about getting better MPG's you can do lots, i would start here: http://fullsizebronco.com/forum/showthread.php?t=120045&highlight=ultimate+mpg

Also check your cat for clogage, or your o2 censor could be bad too.
Hope this helps
 

·
si vis pacem, para bellum
Joined
·
3,511 Posts
did you check your timing???? my 89 with a 302 and auto i can get 17-18 full highway miles

check your cats, timing, o2 censor. what size tires are your running? so you gun the engine alot?? even just city mileage i get 10-12
 

·
Registered
Joined
·
472 Posts
I essentualy have the same truck as you. Mine gets averages 13+ MPG and will do 14.8 at a steady 55MPH with the cruise set. That aint all that great either but it does give you an idea of what to shoot for.

Cheep & easy stuff to do;
Check that your harmonic balancer ring hasn't slipped, then set your timing. Stock setting is 10*, mine's on 12*.
Maintane whatever air pressure in your tires that is marked on the sidewall.
Thoroughly inspect everything associated with the vacume system and repair/replace anything that looks suspect.
Inspect the PCV system and replace the PCV valve with the correct Motorcraft valve.
FWIW, Ford Racing wires have less resistance than common grahite-only wires. Using them (or something simular) will insure that you are getting the most of your stock ignition. You'll need some 9MM seperators to go with them. Both are available at Summit....and Summit is a real fast shipper.
Stop by your local Walmart and buy (8) #25 Autolite spark plugs. Gap them on .050 .
Install a new Motorcraft or Wix fuel filter, air filter and PCV filter.

Other stuff to consider that aint so cheap & easy;
If your Bronco still has the factory exhaust, do SOMETHING to improve it. Do a search on the Forum for ideas.
If your engine has seen over 100K or so, there's no doubt in my mind that the original timing chain/gears are worn to the point that your cam timing has retarded. If that is the case, you can pick up a noticable increase in milage and power by replacing them.
Buy another set of tires & wheels in the sock size. Save them big ones for offroading only.

Hope this helps.

DGW
 

·
si vis pacem, para bellum
Joined
·
3,511 Posts
isnt .5 over kill for stock ignition? i think i gapped mine at .44
 

·
Registered
Joined
·
331 Posts
also an overdrive tranny will help, you just have 3 speeds in that c6... the c6 while a strong tranny is one of the most inefficient trannys out there robbing you of HP and gas mileage... If this is your daily driver id pick one up off of craigslist cheap and swap... whats your rear end ratio? changing that to a higher gear would help too... anything you do as far as tire size and gear ratio will change how your speedoreads like Vannnce said, if your speedo says your going 60 when you are actually doing 70 then you are prolly getting closer to 10 mpg... if your O2 sensor is bad your engine defaults to a rich running program as to avoid detonation... but it should also send a code to your dash light... check and make sure that bulb is good or even there! Ive seen twice where people have removed the bulb either to pass a lax inspection test or dupe a buyer into thinking everything is fine rather than fix a problem...
 
1 - 6 of 6 Posts
Top