Poor MPG

[zachboy82]

Hey all,

I want to say this forum and all of you have been invaluable to me in finding answers and helping me to resolve problems with my current and previous Fords.

That being said, my current vehicle has a problem. I have done a lot of research on these and other forums but I have not been able to locate an answer so hopefully you can help me out!

Firstly, my truck is a 1993 Explorer XLT 4.0 OHV v6 2wd Automatic with rebuilt motor (less than 4k miles on it) and rebuilt transmission.

The truck runs perfectly. But before you get to thinking, "What the heck?? I thought this guy had a problem?" Let me explain...

It runs great, two small problems though. One is that instead of getting the 20-22mpg hwy I expected from a rebuilt motor with less than 4k miles on it, I am only getting 14mpg on the highway. Secondly and I don't know if it is related but when I accelerate from a stop, it seems to be fine for a sec and then it loses about ten percent power while holding the accelerator steady. It feels like the transmission is shifting but its not. The transmission is in perfect working order as far as I can tell. No slipping or odd behavior from it. And I am easily able to maintain highway speeds.

So therefore after all the research I have done on this forum I have tried several things:

-Almost new and clean air filter

-Mass Airflow Sensor is clean and connections seem clean

-Fuel pressure regulator could possibly be bad but no gas in the vacuum
line (side note: the vacuum line is a little loose. Not sure how to fix this
can I tape it with electrical tape?)

-Thermostat might be stuck open and/or temp sending unit may be bad...
replacing these sunday to see if it makes a difference but would this
really cause such a dramatic loss in mpg? (gauge when driving on hwy
is usually in between the "c" and "n"...not as warm as I would think it
should be)

Anyway, I realize I have a few things to do sunday but if anyone has any ideas I would appreciate it very much. I drive an hour and back to work almost every day and this kind of mpg is killer on my bank account.

Thanks!

 

[jhclance]

Check the codes first always. They are like a road map they will take you on a ride and get you where you want to go.

 

[zachboy82]

I went to Autozone and they said they didn't have a code reader that would do it for my particular year. Where do I go to get the codes read?

Thanks!

 

[rhauf]

you can do the "self test" thing (google code reading with paper clip or something) it's sort of confusing, you count the flashes on the check engine light (with the test lead grounded) and look up the code based on that.

 

[zachboy82]

Ah hah! i will do that tomorrow night when i get off work and then go from there.

 

[zachboy82]

ok I did the KOEO test and it was 111 and then 111... did the KOER test and it gave me a 116 at first. but then I read somewhere that 116 is usually output when the engine is not properly warmed up so I did it again after I got home from work (one hour drive) and the engine was plenty warm. This time, no 116. It just gave me 111 across the board. So no codes other than the "pass" code. I just replaced the air filter with a better one. Old one was a crappy fram one. I'm thinking about getting a K&N filter for it but not sure if I want to yet. Anyway, priorities, fix bad mpg first. I got some vacuum connectors so I can fix the loose vacuum line that connects to the FPR. Also bought a new fuel filter. Never hurts to replace the fuel filter. Got new spark plugs and I will put them on sunday morning (and in the process I will be able to see if my old ones are fouled at all). Getting an oil change soon. I'm running out of ideas. If this doesn't fix it I don't know what will.

 

[zachboy82]

Well, I stand corrected. It seems as if the transmission IS slipping after all. It was hard to notice at first but once I did notice, it was pretty easy to tell. When in gear, my tachometer will rev up when i punch the gas and then (while holding the accelerator steady) it will slowly go back down as I get up to speed before it even gets a chance to shift. I thought the engine seemed to lack power but the transmission slip would explain the poor mpg and the lack of power. Crap. Just bought this truck too since my '92 ranger transmission went out on me.

 

[zachboy82]

ok so I guess the questions now are these:

Is it better to overhaul or rebuild the transmission? Does this depend on what is wrong with it? Would synthetic transmission fluid help for now? Would it be a good idea to flush the transmission fluid or use lucas or sea foam or something like that?

Thanks!

 

[rhauf]

when i have trans issues i don't even bother with anything at all. i just replace the transmission.

i blew up the trans in my '93 a month or so ago. installed a new trans from "americancarz" i got a bunch of upgrades (hd converter, shift kit, upgraded clutches/bands etc) and it came out to about $1100 after shipping and everything. (would be about $300 less for a stock build)

the slipping you're describing sounds like first gear slipping.. is this correct? first gear slipping seems pretty rare.. usually slipping is first noticed on the 1-2 shift, or 2-3 shift.

 

[zachboy82]

I honestly would not mind putting in a brand new transmission except for the fact that I paid 800 for the truck. I don't have the money for a new transmission. If I had 1100 dollars, i would have gotten a little bit nicer explorer.

 

[rhauf]

check trans fluid and all that stuff.. i still think the slippage issue you're describing is strange, any chance you could post a video (on youtube or something) of the tach and speedometer and what they do on acceleration?

as for a new trans... think of it this way, if you put a new trans in you're $800 explorer, then you'll have an explorer with a nice new transmission (if you spend the 1100 like i did then you'll get a better than stock unit) on the other hand, if you just bought a slightly more expensive explorer to start with, you'd still have one with an old transmission in it. i paid $700 for my explorer 5 years ago, first thing i did when i got it was replace the heads and heads (they were cracked and it overheated). new (upgraded) heads, bolts, and gaskets and all came to $715, more than i paid for the whole truck! now i'm putting in a new trans. i think it does pretty good though, i've put 70,000 miles on it since i did the heads (it has 217k total now) and it's quite reliable. i'm also not easy on it at all. i tow a flatbed trailer with other cars and trucks behind it, as well as a boat. i floor it from every stop, and i 4x4 it too. if it comes down to it, get the trans it'll be worth it.

 

[zachboy82]

Ok... I'm an idiot. I don't think the transmission is slipping now. It just seems like the truck doesn't have as much power as it should. it might have a tow package on the transmission or something, who knows. Anyway, I'm replacing the fuel filter and spark plugs tomorrow morning. If all of this fails then I will have to spend the money on the fpr. And you really tow other cars with your explorer?? wow... I had no idea they could tow that much!

Thanks for the replies and I will let you know how it is doing after the plugs and filter change.

 

[rhauf]

you know these explorers aren't exactly "fast", they weigh 4,600 pounds, and they have 155 horsepower. maybe you're expectations are too high?

as for towing. you can tow a lot, if you're careful.. the long(ish) wheelbase of the explorer, and reasonably heavy weight make it a decent towing vehicle, as long as you're patient with acceleration (and keep it in a lower gear so it doesn't lug the engine too much)

new fuel filter is definitely a good idea. remember you need a set of those quick-disconnect tools to change it (the round plastic things).

 

[92exp4x4]

After blowing up my 90 351 Bronco, I bought my current tow rig. A 97 F250HD with the 7.3 turbo diesel. That should do it i think!

 

[rhauf]

is that an IH logo on you're trailers fender?

yes broncos are horrible for towing, their wheelbase is too short. (i have a couple broncos ive towed with them as well) my explorer actually tows easier than the bronco (not in terms of horsepower, but in terms of fishtail and stuff)

 

[zachboy82]

Ok so tried replacing the fuel filter... couldn't get it off. I tried using the metal tool and I got the rear line off easily but the front line would not come off. I figured the metal on metal of the tool was just not "slippery" enough and that it wasn't allowing it to go in far enough so I exchanged it for the plastic tools. I broke two of the plastic quick disconnect pieces. So I figure, screw it, I'll just take it to pep boys and have them deal with it... no... they wanted $80 to change a fuel filter...So finally i ended up calling around at different small auto shops to see what they would charge me. Taking it to a guy tomorrow to replace it, $20. I'm tired of messing with it. Oh on a side note, my a/c just quit on me. It was probably recharged right before I bought it. Probably has a leak somewhere...oh well. Anyway, thats the update!

And thats awesome that these little explorers are so good at towing. Its just what I was looking for. I will want to be able to tow a boat sometime soon.

Also, quick question, my explorer has one of those tow hitches on the frame on the back but instead of the normal size square hole it has the smaller one. Does anyone know how much this can handle? Is there any reason to put in the adapter that turns the smaller squared hole into a larger one?

Thanks again!

 

[zachboy82]

Ok so, finally got the fuel filter taken care of... the old one was rattling. Not good. Anyway, the truck was still losing 10% power as I accelerate so I went ahead and got the fpr. Replaced the fpr about half an hour ago. I drove it to see how it was. it seems to run a little better and stuff but I give up on the 10% power loss. I don't have a clue what it is. We will see if the new fpr helps my mpg at all.

 

[rhauf]

Ok so tried replacing the fuel filter... couldn't get it off. I tried using the metal tool and I got the rear line off easily but the front line would not come off. I figured the metal on metal of the tool was just not "slippery" enough and that it wasn't allowing it to go in far enough so I exchanged it for the plastic tools. I broke two of the plastic quick disconnect pieces. So I figure, screw it, I'll just take it to pep boys and have them deal with it... no... they wanted $80 to change a fuel filter...So finally i ended up calling around at different small auto shops to see what they would charge me. Taking it to a guy tomorrow to replace it, $20. I'm tired of messing with it. Oh on a side note, my a/c just quit on me. It was probably recharged right before I bought it. Probably has a leak somewhere...oh well. Anyway, thats the update!

And thats awesome that these little explorers are so good at towing. Its just what I was looking for. I will want to be able to tow a boat sometime soon.

Also, quick question, my explorer has one of those tow hitches on the frame on the back but instead of the normal size square hole it has the smaller one. Does anyone know how much this can handle? Is there any reason to put in the adapter that turns the smaller squared hole into a larger one?

Thanks again!

On you're A/C, just look at all the O-ring connections (quick disconnects). you can usually tell which one is leaking by looking at it (it will be oily from the a/c lubricants seeping out).. on my '93 i had an a/c leak too, turned out to be the fill valve on the accumulator.

if you're going to use it for towing, get a HUGE trans cooler. explorers have a fairly high-stall torque converter, which will generate a lot of head while towing, so a good cooler is a must... and keep it out of overdrive of course.

on the hitch, i'd probably go to harbor freight (or wherever) and get one of the larger reciever tubes, and cut the small one off, weld the large one on. a muffler/welding shop could do this for you as well.

 

[MrWizard]

You might also want to check your plug wires. A bad wire can drop your
gas mileage significantly.

Both measure the resistance of the wire ( good ones would be 5-10K ohms
per foot) and check for cracks in the insulation.
One simple way of checking the insulation is to look at the wires in the dark,
while the engine is running. And spray them with water in a spray bottle.
If you see visible arcing the insulation is bad.

 

[zachboy82]

sweet! Thanks for the tips. I will check my plug wires when I change my plugs. i might as well change the wires at the same time anyway though... And I will also check the o rings on my a/c. Where are they if I may ask?

Rhauf, thanks for the info on the towing. I will definitely do that when I get my boat. (whenever that is...lol.)

Thanks!