Stop your complaining. That is not only better than average, its damn good. I think that exhaust and O2 sensor are a problem although I will add, if you're getting mileage that good I can't imagine what you'd get with it all proper like.

Mike

 

I agree. Fullsize Broncos are VERY HEAVY vehicles with VERY POOR Aerodynamics. No matter how well you tune or tweak it, your MPG will NOT get much better PERIOD.

Oh yea, those claiming 20 MPGs are full of ****.

 

First off, I will grant that I mistyped the word LEAN. It should be RICH... and this is why.

The fact of the matter is that the sensor is an oxygen-reactive variable resistance type sensor. It does not compare anything. It alters its resistance value (via the chemical makeup of the probe at its tip) based on the oxygen levels to which it is exposed. At very high oxygen levels its resistance value is approximately 0.1 volt and at low oxygen levels the resistance is approximately 0.9 volts.

IF the O2 sensor is to get an accurate reading it MUST be able to sense the exhaust from BOTH banks of cylinders. If not, the bank NOT sending any exhaust past the sensor could feasibly be belching raw fuel or ONLY air and the O2 sensor would not recognize the problem! (Fortunately YOU would because the thing wouldn't run very well if at all). The computer will take that reading and interpret it based on preprogrammed parameters within the software for that particular engine/vehicle. The computer cannot adapt its programming to the oxygen levels expected to be found in a four-cylinder engine. It will take the resistance value and apply it as though the entire engine were being analyzed rather than just four cylinders from it. While the sensor does not measure volume, it does react to the level of oxygen in the exhaust. Since it is NOT capable of COMPARING exhaust gas-to-oxygen levels, the reading (since its only coming from only ONE bank of cylinders) will register at the computer as being RICH because there will be HALF as much oxygen present in the exhaust from ONE bank than there will be from both banks. The O2 sensor ONLY reads oxygen levels and does not know that there is proportionately less exhaust gas as well as less oxygen.

So to your point, you are correct it would NOT yield a lean condition but rather a rich condition. Either of which will be detrimental to your fuel mileage since the lowered fuel delivery that results will make the engine work harder to achieve the same torque, speed, etc.

 

I wish I got remotely close to 20mpg :|


I get 12 on average.

Then again, I'm assuming I'll drive maybe 4k miles a year total in my brick, all it does is haul my yz-250, yzf-350 to Glamis or El Mirage.

Not bad IMO, bought the baby about a year ago, with 93k miles for $2370. she now has 95,700 and some change

Very Clean, only repair I had to do to her so far was brakes

94 Bronco XLT

 

Agreed, there are some pretty good hills between Topeka and Junction City. (JC guy here) From west Salina to Eastern Colorado is FLAT though!

 

Just curious, did you adjust your milage for the 31" tires? My XL came with the little tires and there is about 7 % difference on the speedo. Mine is lifted a couple of inches with the spoiler off and a 3 bar roof rack and gets about 14 (10 pulling my 21' camper). When it was new I recall getting 17 on a long trip.

 

Yes sir it is! I've traveled I-70 a lot between Denver and KC. KC to Salina is pretty nice; the rest is pretty boring. The worst stretch is the KS/CO state line west. YAWNNNNNNN! Not a lot of places to stop either.

 

I'm in an 86 F150 4x4 with 31" tires, a 351W HO, 600cfm Edelbrock, dual exhaust, and a fresh tune up. Runs great. Last mileage figured was 9.8 mpg. I envy all of you.....

 

My 93 Bronco 5.0 with E4OD, 3:55 gears and 31x10.50x15's gets about 13 highway.
My 90 Bronco 5.0 with AOD, 3:55 gears and 33x12.50x15's gets about 10 highway.
My 90 F150 5.0 with AOD, 3:55 gears got 17.08 on a 100 mile trip but only about 55-60 mph. Same truck ran up to PA. to pick up a 351W, C6, and 5.0 short block got 10 mpg. But, I was running 70-80 mph, had hills, and a load on the return trip.
My 87 F250 6.9 with C6, 4:10 gears and 265/75/16's gets 10mpg no matter what.
I've never checked my 91 Bronco 5.8, E4OD, 3:55, and 31x10.50x15's but don't really care. You should feel fortunate to get 14mpg.
I should add that my driving habits are generally to leave the pedal on the floor until I reach the desired speed which is not conducive to good mileage with any stop and go driving.

 

Ok, Ok guys, so I confused my cities. I made the full drive from St. Louis to Denver. Anyone subjected to THAT much of I-70 is bound to lose track of where they are. Only changes I noted were that the corn and the soybeans occassionally swapped sides of the highway.

 

Yep that is a cwapy drive, I did it in a bus which wouldnt go more than 62 that sucked

 

my bronco is an 88' 5.0 with aod. i have 32's on it, true duals and k&n i used to get around 17. but 30000 miles later im down to around 15, it now has 228*** miles on it.

 

I wish I got 14 MPG in mine. I get HIGHWAY 9-10mpg. I got a 351w, true duals, 32's, and 4bbl holly.

 

Everybody missed a real important point - with 31" tires, the speedo will be about 10% off. Ditto with your odometer. If you're doing 60mph, you're really doing 65 mph. Your mileage calculations will be off by a bit.

Also, what everyone is else saying is right - you have no business complaining about 14 mpg.

 

in that case, he got around 12.6 mpg. a little low..