V6 Mileage Problem

[nmdag]

1996 4.0L V6 AWD, 175k miles, ~10mpg city driving

Bought it out of state, and drove it in, seemed to be getting decent, probably ~26-29mpg, mileage on the freeway. (about 5k miles ago)

Had transmission rebuilt, replaced IAC, replaced an O2 sensor, everything is fine, but had a shop look at it for other issues and they diagnosed a faulty ignition coil pack, and plugs/wires in need of replacing from a series of misfires. 5 thousand miles later my mileage turns to crap.

Is the coil pack the reason for my ~10mpg in city driving? This has happened within the past ~1K miles. Plugs/wires would be getting replaced with them.

Mileage is significantly worse in 4WD auto, but the problem is still present in 2WD, could I be need a diff fluid change as well?
edit- keep in mind I do know that economy is pretty much always going to be worse in 4WD vehicles vs 2WD, used to drive a Subaru. It just seems significantly worse.

http://www.amazon.com/gp/product/B0...rue&ref_=ox_sc_act_title_3&smid=ATVPDKIKX0DER

Too bad my arms are too big to do spark plugs myself. Have to take it into the shop to get that done.

 

[1998Exp]

First, congratulations on your 26-29 freeway mpg! That's a record, considering that Ford specification for highway driving is around 20.
Yes, poor ignition will cause mpg degradation. I just replaced my long overdue wires and saw about 10% improvement.
I may be wrong, but unless you have some sort of heavy grease in the diff instead of the correct fluid, replacing it won't buy you more than 1-2% - if that.
I wouldn't put too much value on your 10 mpg city driving. If you live in a city with a stop light every couple blocks and heavy traffic, 10 mpg is probably nothing unusual.
Incidentally, you don't need long arms to replace spark plugs. What you need to do is to go through the wheel well, not from the top.

1996 4.0L V6 AWD, 175k miles, ~10mpg city driving
Bought it out of state, and drove it in, seemed to be getting decent, probably ~26-29mpg, mileage on the freeway. (about 5k miles ago)

Had transmission rebuilt, replaced IAC, replaced an O2 sensor, everything is fine, but had a shop look at it for other issues and they diagnosed a faulty ignition coil pack, and plugs/wires in need of replacing from a series of misfires. 5 thousand miles later my mileage turns to crap.

Is the coil pack the reason for my ~10mpg in city driving? This has happened within the past ~1K miles. Plugs/wires would be getting replaced with them.

Mileage is significantly worse in 4WD auto, but the problem is still present in 2WD, could I be need a diff fluid change as well?

Too bad my arms are too big to do spark plugs myself. Have to take it into the shop to get that done.

 

[nmdag]

First, congratulations on your 26-29 freeway mpg! That's a record, considering that Ford specification for highway driving is around 20.
Yes, poor ignition will cause mpg degradation. I just replaced my long overdue wires and saw about 10% improvement.
I may be wrong, but unless you have some sort of heavy grease in the diff instead of the correct fluid, replacing it won't buy you more than 1-2% - if that.
I wouldn't put too much value on your 10 mpg city driving. If you live in a city with a stop light every couple blocks and heavy traffic, 10 mpg is probably nothing unusual.
Incidentally, you don't need long arms to replace spark plugs. What you need to do is to go through the wheel well, not from the top.

Well I was going downhill (literally from high elevation to sea level) in OD with the cruise control on for about 2,000 miles so it's not too much of an accomplishment. Probably had the wind behind me as well

The only thing that stands out was I was doing fine for a thousand miles, same driving style and location, but the last few (3-4) fillups have been painful. I swore I used to get about 20 in town before, driving slowly with fuel economy in mind.

I'll have to price a diff fluid change and do some road testing before I can make any certain statements regarding fuel consumption in 4WD vs 2WD. But that's for another thread, I'm sure there will be some people interested in knowing the exact numbers.

Coil pack comes on Monday and then it's to the shop to get plugs and wires. Honestly going through the wheel well sounds like a PITA too and I probably don't have the correct tools (ie plug wrench) to do the job anyways. I'll stick to the simpler stuff like the coil pack (I do have a hex head screwdriver), which the shop wants to charge $200 for anyways.

 

[lobo411]

10 MPG city is absolutely what I'd expect in a 4wd. I have the exact same setup as you (1996 w/ 4.0 OHV) except I have 2wd, and I generally get about 14-15 around town. Generally 17-18 on the highway. I like to go fast. If you get X mpg @ 50 MPH, and you go 80 MPH instead, then you save gas because you get there faster. Right?

 

[jmvb]

Did you check your coolant Tº indicator?
Your truck reach service Tº faster?

 

[nmdag]

10 MPG city is absolutely what I'd expect in a 4wd. I have the exact same setup as you (1996 w/ 4.0 OHV) except I have 2wd, and I generally get about 14-15 around town. Generally 17-18 on the highway. I like to go fast. If you get X mpg @ 50 MPH, and you go 80 MPH instead, then you save gas because you get there faster. Right?

Haha. The only problem is I'm not used to getting 10mpg, like I said, I swear I used to get about 20 around town. I've been babying the thing since the transmission rebuild. Though I am now addicted to the rumbling from my little 4 liter.

Did you check your coolant Tº indicator?
Your truck reach service Tº faster?

Coolant temp is fine, though I have never really driven it long enough at once to get it anywhere above baseline. I think I forgot to mention that I have a slight coolant leak, which was mostly fixed with a bottle of Stop Leak (grey bottle).
Oil is fine as well. Though I could have malfunctioning gauges or sensors.
I haven't experienced any overheating.

 

[koda2000]

There is no way these vehicles, as delivered, can get 20 MPG city and 29 HWY unless you're always driving downhill with a tailwind. The V6's and V8's get very similar fuel economy and the best I've ever seen out of any of mine is 17'ish city and 23 hwy under optimal conditions (fresh tune-up, cool weather, 35 PSI in the tires, no A/C, flat roads, no traffic and speeds 50-55).

I recall messing with a guy at work back in the early 70's, where we added a gallon of gas to the tank of his new VW Beatle everyday until he took it in for it's first service. Then we stopped adding fuel. He swore the dealership did something to his engine because his great gas mileage had suddenly stopped.

 

[Dude13450]

There is no way these vehicles, as delivered, can get 20 MPG city and 29 HWY unless you're always driving downhill with a tailwind. The V6's and V8's get very similar fuel economy and the best I've ever seen out of any of mine is 17'ish city and 23 hwy under optimal conditions (fresh tune-up, cool weather, 35 PSI in the tires, no A/C, flat roads, no traffic and speeds 50-55).

I recall messing with a guy at work back in the early 70's, where we added a gallon of gas to the tank of his new VW Beatle everyday until he took it in for it's first service. Then we stopped adding fuel. He swore the dealership did something to his engine because his great gas mileage had suddenly stopped.

Now, that is hilarious! I can't wait to see what kind of MPG's my 96 will get. I picked it up Friday with a transfer case shift motor issue so the transfer case wasn't engaged at all so the car wouldn't move in gear. I manually manipulated the shifting actuator and got both the LO and HI ranges to work.

I got it with 184k which for its age is actually pretty good in my area. I'm going to get it licensed and insured later this week, and hopefully I will get decent mileage out of it; however, I'm not too worried about it because it's going to be my winter vehicle and for summer fun (offroading), so it'll be driven around 3k a year roughly.

 

[koda2000]

Now, that is hilarious! I can't wait to see what kind of MPG's my 96 will get. I picked it up Friday with a transfer case shift motor issue so the transfer case wasn't engaged at all so the car wouldn't move in gear. I manually manipulated the shifting actuator and got both the LO and HI ranges to work.

I got it with 184k which for its age is actually pretty good in my area. I'm going to get it licensed and insured later this week, and hopefully I will get decent mileage out of it; however, I'm not too worried about it because it's going to be my winter vehicle and for summer fun (offroading), so it'll be driven around 3k a year roughly.

I don't worry too much about gas mileage either. During the summer months I typically see 14-15 around town and 18'ish hwy with my 5.0L's. After all it's a 4,000 pound vehicle with the aerodynamics of a brick. During the winter that increases to 17+ in town (w/minimal traffic) and maybe 21 hwy. I can live with that.

 

[nmdag]

I recall messing with a guy at work back in the early 70's, where we added a gallon of gas to the tank of his new VW Beatle everyday until he took it in for it's first service. Then we stopped adding fuel. He swore the dealership did something to his engine because his great gas mileage had suddenly stopped.

Greatest thing ever.

Also yes. I was going downhill with the AC off (most of the time, my max ac blows COLD) and with minimal traffic.

I don't worry too much about gas mileage either. During the summer months I typically see 14-15 around town and 18'ish hwy with my 5.0L's. After all it's a 4,000 pound vehicle with the aerodynamics of a brick. During the winter that increases to 17+ in town (w/minimal traffic) and maybe 21 hwy. I can live with that.

I don't worry about it too much, the sound of the little V6 almost makes it worth it, but, in this case, the poor mileage is indicative of a possible mechanical/electrical problem which would mean that I don't get to drive my little Exploder around because it might die on me.

Now, that is hilarious! I can't wait to see what kind of MPG's my 96 will get. I picked it up Friday with a transfer case shift motor issue so the transfer case wasn't engaged at all so the car wouldn't move in gear. I manually manipulated the shifting actuator and got both the LO and HI ranges to work.

I got it with 184k which for its age is actually pretty good in my area. I'm going to get it licensed and insured later this week, and hopefully I will get decent mileage out of it; however, I'm not too worried about it because it's going to be my winter vehicle and for summer fun (offroading), so it'll be driven around 3k a year roughly.

If you got the V6 you might be pleasantly surprised. Does this gen Explorer have a good reputation in the snow? I know the 4WD is on-demand so it may handle differently from say a Subaru or a Jeep with ~50/~50 AWD.

 

[koda2000]

Greatest thing ever.

Also yes. I was going downhill with the AC off (most of the time, my max ac blows COLD) and with minimal traffic.


I don't worry about it too much, the sound of the little V6 almost makes it worth it, but, in this case, the poor mileage is indicative of a possible mechanical/electrical problem which would mean that I don't get to drive my little Exploder around because it might die on me.


If you got the V6 you might be pleasantly surprised. Does this gen Explorer have a good reputation in the snow? I know the 4WD is on-demand so it may handle differently from say a Subaru or a Jeep with ~50/~50 AWD.

FYI, I currently own 2 SOHC V6's and had a 3rd before it imploded. I don't care for the SOHC V6. It's to problem prone. Give me the 4-door V8 any day. I would guess the short wheelbase on the Sport might make it less than ideal in the snow, but that's not an issue where I live. If it snows, I just stay home until it melts.

 

[J_C]

They do fine in snow in 4auto but like anything it depends on what tires you have on it.

Mine is only getting around 10 MPG but that's because I just take it up to a nearby store every now and then to give it some exercise, stopping at stop signs and lights every 20 seconds or so... at least gas prices are lower now.

 

[45Frank]

I've had two explorers, one was new in 2000 with a six cylinder that had tranny and electrical issues the entire six yrs I had it, never did better then 14 mph usually a little less.
I just bought a used 2000 with 147000 miles and average 17 plus and it's never been on the highway. That's in the mountains of Western NC. Lowest about 16.5 highest 18.4. I drive conservative and keep it out of OD when climbing mountains.
This one has the 5 speed auto with the auto four wheel drive, the other had the 4 speed auto with the two, four and four low.

 

[nmdag]

Ignition coil pack, spark plugs, and plug wires were replaced today. Along with a fuel system cleaning with emphasis on the throttle body.

Already noticing smoother idle and acceleration, and there seems to be a little hp gain as well.

Thread will be updated next fillup, wish me luck.

 

[ccm2001]

When i changed my original Motorcraft spark plugs to NGK G powers i noticed a huge decrease in fuel milage. So i went and swapped them out again for Motorcrafts platinums car ran like a dream. Also changed my coil and wires

 

[J_C]

When i changed my original Motorcraft spark plugs to NGK G powers i noticed a huge decrease in fuel milage. So i went and swapped them out again for Motorcrafts platinums car ran like a dream. Also changed my coil and wires

Which engine? When I switched my plugs and wires on my V6 SOHC to NGK G Powers # 3403 and ACDelco 16-826K wires, I didn't notice any mileage decrease, though it did start faster, run smoother and got rid of a misfire I had on rainy days. I didn't change the coil pack.

In retrospect, considering my alternator died a few months later, it might've just been a combination of low battery voltage plus the original plugs and wires didn't produce a hot enough spark any longer if the air was humid. I didn't notice any cracks in the wires or see arcing when checking it at night.

Is it possible you had a wire that wasn't clipped onto the plug so it occasionally misfired? I've come back to double check my work before (on a different vehicle) and found I had left one wire half off like that.

 

[masospaghetti]

Big heavy vehicles like Explorers are very much at the mercy of the driver for decent fuel economy. Regarding spark plugs - it's important to use the double-platinum plugs (installed as OE on these engines) because of their waste-spark design. Basically, a copper plug or single platinum plug will wear out much, much, faster than you might expect.

 

[ccm2001]

03 sport 4.0 sohc