I bought a truck about a week ago. Its a 2000 Ford Ranger Super Cab with a 4.0 v6. Automatic transmission. It is a 4x4 but I only drive it in 2wd. It is lifted and has 32 inch tires. So far I have put new tires on it. The other ones were shot. I have also changed the oil to Mobile 1 high mileage synthetic and have used one small bottle of fuel system cleaner. It came with a cold air intake and dual exhaust. Pipes aren't very big on it though. It has been very cold outside.
I am going to commute to college this semester about an hour away. Unfortunately I have class five days a week. I wanted to only have to go MWF or T TH, but that didn't work out.
Heres the deal. I am getting awful mileage. I calculated about 14 mpg. I would say most of it was highway driving, and I baby the throttle. I know it is a truck but I would expect a little better mileage. It is kind of a small truck after all. I plan on making a HHO dry cell and making some small changes/maintenance to squeeze out a little better mileage. But is something possibly wrong with the vehicle? What are some things I should check that would possibly be bringing down my mpg?
There's unfortunately a lot of things that could be wrong.
The EPA says you should be between 15 and 20.
I'd start by first determining if the oversize tires have also been accounted for at the speedometer. You could be traveling many more miles than you think because the odometer isn't accurate. That also means you may be traveling faster than you think for the same reason which will lower FE. Try using a GPS to figure out how fast you are traveling (and miles traveled), or go to tirerack.com and use their calculator.
That aside, lower your highway speed to 60mph if you haven't already. You'll see noticeable gains in FE that way.
Regular maintenance may help if it hasn't been done in a while; plugs, wires, air/fuel filters, etc.
The cold air intake is likely losing you some MPG's. They tend to use more fuel to make the more power they offer. You could probably find one at a bone yard or maybe craigslist as a take-off piece. Heck you might be able to trade someone that fancy intake for the stock one! Post an add, I'm sure it would work.
Tire pressure. At least at the numbers inside the door.
Those are the biggies, but don't forget it is winter. Assuming you live in a place where there are colder temps and weather, winter fuel and weather can hurt FE.
Start a gaslog and document your process. There's a lot of good help for you here.
Don't get your hopes up too much. I had a 1997 4.0 4x4 Ranger and it was really a pig. Lited and with oversized tires it would be even more of a pig. 14MPG is pretty good for that vehicle, IMO. As benfrogg said, you might be doing a little better than you think if your speedometer was never adjusted for the larger tires.
The lift exacerbates the bad aerodynamic qualities of the truck, making it much worse. The larger tires probably are not designed with rolling resistance in mind, and also if you're not re-geared for them then you could be running ratios that are too tall for efficiency (and acceleration), although if you're not driving hard then the extra tall gearing may help instead of hindering.
It sounds like you really needed new tires for safety, but they are detrimental to fuel economy. Worn tires have less rolling resistance. What pressure are you running?
Pipes, intakes, synthetic oils, all the modifications that people want to make because they're fun or supported by a lot of marketing...all of them don't really help with fuel economy. HHO has lots of supporters and endless legions of experimenters but few well-documented credible results. At least it can be done for free or nearly free using free plans, household materials, and generic commodities, so if you try it you're not necessarily supporting a snake oil salesman.
Who ever owned the truck before the guy I bought it from had huge tires on it. I don't know the size they were. But the last owner replaced them with used stock sized tires. I noticed that the speedometer was about 10 mph off. He drove it that way for 2 years and only put 10,000 miles on it. (So the truck should actually have less miles on it than it shows!) I waited until I got my new tires to adjust the speedometer. I used a GPS and it is now pretty accurate.
On the way to school I was driving the speed limit, which is 70. I wanted to make sure I was there on time. But on the way back I drove about 62 and drafted behind a semi at a pretty safe distance. It was running about 2100 rpm.
But in town I never accelerate much over 2000 rpm. I feather the throttle and use my brakes as little as possible. I live in a small town so I never have to sit and wait at traffic lights for more than 10 seconds. It will literally switch to green about 5 seconds after the sensor is tripped. And I conserve momentum going into turns.
I plan on replacing the tranny and axle fluids with synthetics. Mainly because I don't know when they were changed last. I am hoping that will give me an extra mile or two per gallon. Also is there a way to grease or lube the tires so they spin with less friction? I would think that would add up to saving some gas too. I will replace the spark plugs and wires sometime soon. The tires are at 35 psi right now. I will pump them up to 40. And I am going to make a log book and document my fuel consumption and mileage.
I have also thought about covering the bottom of the vehicle to improve the areodymanics. I am thinking about using thin sheet metal. I will be taking it off road sometimes and want to stay away from plastics or vinyls. Any estimates on how this will help my efficiency or not?
I didn't think that the bigger tires would hut my mileage much at all. That is as long as I accelerate slowly to get them moving because They weigh a little more. After all they are going a farther distance for the same amount of revolutions as smaller tires would.
Bigger tires affect your FE in more ways than just how they affect your gearing. They have more aerodynamic drag and make your vehicle higher. They are likely to have more aggressive off-road tread.
There ought to be plenty of skid plates made for Rangers, maybe you can find some in a junkyard cheap. That would help with the worry about plastic. You will still need to do some custom stuff to clean up the skid plate and extend it over areas it doesn't cover.
With the solid axles (I can't remember, does it have a solid front?) I wonder if there's something that can be done about their aerodynamic drag besides lowering the vehicle so they'll tuck in.
I don't know about the Ranger, but on my truck feathering the pedal results in poor mileage (because you extend the time spent in lower gears). I get better mileage giving it 1/4 to 1/2 throttle, and getting into a more economical gear quicker.
Second on Jay's suggestion. Better to get to the cruising gear as soon as possible without womping it. My Ranger with 3.0L would shift into overdrive around 45mph. Once in gear, you might be able to stay in it down to 40mph.
The wheel bearings could probably do with being greased.
The cold air intake may not actually be one. I ran one, and air temps by Scangauge were about the same as with the dryer tube running to the exhaust manifold.
I'm not familiar with the 4x4 system, but a shift on the fly system may not have the hubs completely off when in 2wd. If you rarely use it, manually turning the hubs off might be possible.
That is one thing my brother in law did, now that you mention it. He removed the automatic hubs and replaced them with manual ones. His opinion was that automatic hubs were nothing but problems, and manual ones never broke.