93 5L bronco MPG issues

Hey fellas, i have a 93 EB 5.0 auto, with about 190k on it. it is in good shape, and runs pretty well.

My "as acquired" MPG was 13.1. I replaced the tires with normal 31's, upgraded the ignition components and set timing to 13 ADV, removed the belt fan for an electric unit, and replaced the thermostat with a stock temp unit. I also replaced the fuel filter, fuel pump, air filter, and oil and filter. The driving experience was much improved, power delivery increased, and i was sure id be rewarded at the pump, too. Alas, after a tank of ALL HIGHWAY driving, at or less than 2000 rpms, 12.94 MPG. Essentially no change, if not a little worse.

My suspicion lies in the thermostat. I replaced it because I thought the old one was stuck open or something, as it took FOREVER to warm up. The best I got was the needle on the left edge of the cold mark. After the swap, I am able to get it to the 'N' in normal, but it still takes a good while. Now, in the quest for HEAT cause its cold in Ohio, i have the electric fan OFF, cardboard in front of the radiator, and it STILL takes forever to get to 'N'.

I'm wondering if something is still wrong with my cooling system, and that not getting to operating temperature is preventing me from going to closed loop, and could be why my MPG is so bad.

I'm kind of at a loss here, as I have never has this issue before. Usually I have trouble keeping 5.0L's from overheating. I would think that with 13 degrees of timing, essentially no fan, and a blocked off radiator, I'd be on the verge of overheating, not still cold blooded...I mean, its sorta cold here, 30's in the morning, 50's in the day, but that's not THAT cold.

What else am I looking at that could be preventing me from getting to Operating temp? Or do y'all even think that this is my MPG issue? I would expect at LEAST the EPA of 17hwy as it sits...

Thanks for your assistance in advance, GRM.

-J0N

Bad temp sender(s) making it run rich? Isn't this also the era of "idiot gauges"?

My friend had a brand new 93 Bronco with the 5.0V8 and I do not recall him doing much better than 14MPG, add a 190K miles to the truck and you might be doing ok. As for the temp issue I would replace the temp sending unit and see if that changes the reading, with the rad blocked and no mech fan I would think the truck would be running hot.

Do you have heat coming from the vents? Have you checked the blend air door to see if it working?

A few things I have found that can help with MPG have the alignment checked, check to make sure the brakes are not dragging (before and after driving), and clean the MAF.

Paul B

You set timing to 13 BTDC with the SPOUT removed and then reinstalled it, correct?

Jeff

Did you run codes?

You're in double digits. That's pretty good actually :D

a 5.0 with the gearing of a Bronco ? and you're not happy with 14 ? like PRB said .. you're in double digits

not to mention adding about an inch of diameter to the tires from stock.

JKleiner has a good point... you're sure you had the SP disconnected when you set timing? Its also possible that your new stat is faulty.

Also keep in mind that your indicated odometer distance is now a touch off with the 31" tires. You've actually gone farther than the odometer suggests.

Plus, a difference of 13.1 to 12.9 is easily explainable by driving on a couple more hills, the gas pump shutting off one pint later than the last time, a difference in atmospheric pressure, the moon phase, and whether or not you prayed to Jobu that day.

It wouldn't be from switching to winter blend gas would it? Wasn't sure how long ago you got your baseline

I think that is what they get. I had a '92 full size two door blazer with 350, a buddy had a '94 Bronco with 302... I got around 17 and he got around 13, no matter what.

Do the "SixLitre tune up", check and fix any CELs and be happy with it!

You're not getting any detonation with that much advance?

if i was to bet, i'd say that it's a winter blend gas/cooler ambient air temp issue.. my GTP just dropped from a normal of 27mpg all summer long to no better than 23 for about the last month.. nothing else has changed except the colder weather and the matching winter blend gas.

the bend door works good. if i let it sit and idle for awhile i get ok heat. i can get temp to get as high as 'R' if i let it idle for like 45 mins. brakes are ok, alignment is unknown, but not obviously bad. Mass air, no maf.

I know these can get better on 31's, i have a 95 F-250 with a 5.8 getting 16...

i timed it correctly, unplugged spout. im not new to fords. the "6litre" tuneup was done.

tanks are a week apart. i drive 400mi per week.

i might have the stat in backwards, dont really know. i put it in spring towards the firewall. is that wrong?

_jon

Towards firewall is correct.

im going to go pull codes now. report in a few...

-J0N

operating temp at idle, sensor readings:

ECT 0.6v, 202 degrees

idle, 850-870

EVP 0.5V

EVR 29%

IAC 34%

IAT 141 DEGREES

LOOP STATUS CLOSED (OPEN ON START UP SO IT IS SWITCHING)

MAP 10.5-10.8 IN HG

OS SEN 1-0.05 - 0.80 VOLTS

SPARK 23-26 DEGREES AT IDLE, MOVES WHEN REVVING

ST FTRM1(%)- [-14] (WHAT IS THIS?)

TP MODE - P/T (WHAT IS THIS?)

TPS (V)- .9 (MOVES WITH TB MOVEMENT)

VPWR (V)-13.9VREF (V) 5.0

VSS - 0 (MOVES WHILE DRIVING, MATCHES SPEEDO).

KOER CODES:

SYSTEM PASS

KOEO CODES

654 TRANS RANGE SENSOR NOT IN P (SHIFTER IS REALLY LOOSE) 626 COAST CLUTCH SOLENOID CIRCUIT MALFUNCTION (IT DOESNT COAST WORTH A CRAP WHEN YOU TAP OFF CRUISE AT 70, SO THIS KINDA MAKES SENSE) 111 SYSTEM PASS

an hour later...

i removed the 600 mile old plugs. three of them are black and fuel soaked, the others are a nice light brown. looks like i have some sticking injectors...

what gears are in it? and what gears are in the other truck? you might have highway gears in the Bronco, which works in conjunction with the taller tires to lug the engine at highway speeds... the truck might have deeper gears, which puts the engine in the meaty part of the torque curve and thus gets better mileage.

regarding the heat: what temp is the thermostat? i'm a fan of 195's for more heat and better mileage than a 180..

also, now that i was able to read the engine temp directly, it looks as if the 'n' is about 200, and the 'r' is about 230, so the gauge reads WAY lower than my f250, but is at least predictable. it is getting warm, (though slow)...

gears are both 3.55's. both run 31 10.50's. at about 70mph, im turning right at 2k in the bronco, same for the 250. i have this stupid sun visor bolted to the roof, (long fiberglass overhang) that my 250 does not...could the be hurting me?

Looking at injectors on Evilbay now...

-J0N

I get 17-18 in my 5.0 mustang. I would expect a bronco to get 13-14.

Was the stock tire size on the bronco, 31's or 235's? if it's supposed to have 235's the odometer will be off and will negatively affect your mileage calculations.

if i correct the calculations based on tires size, i get about 13.8. a difference, yes, but before any changes were made, i didnt make any corrections, and the tire size was the same. (the tires were FAR nobbier and mud oriented, they are now highway tread tires).

I think i will upgrade to Bosch gen 3 injectors, and have the exhaust redone by a local shop, and see what that yields me.

Thanks for the help GRM!

-J0N

how much money are you going to spend to try to save a couple of dollars a week?

i drive 400 miles per week, as of now thats 30 gallons. over the course of a month, thats 120 gallons, at roughly $3/gal. $360 total per month to drive to work, and thats JUST work. so call it $400/month to drive. if i can decrease my consumption by 30% (4mpg increase), that number will fall to 23.5 gal/week, or 94 gal/month. at a cost of $3.00, thats $282, so call it $300. SO a hundred dollas a month, or $25 per week. i have right at $120 invested in the search for 17-19 mpg. IF i attain the results im after (and i will, eventually), ill get the money back for the parts in less than two months. the other 10 months out of the calendar year, ill save almost $1000.

So, can i have $1000, novaderrick? ill stop my quest right now, my paypal account is...

EDIT - i guess i didnt answer your question. The answer is, apparently, LESS than $1000.

-J0N

You'll easily get 17-19 mpg... Of course you'd have to sell your Bronco and buy a newer truck to get it!