My son bought his 4.0L '96 4x4 about 3 months ago. When we brought it back from Minneapolis the gas mileage was pretty low for highway, about 13mpg. He drives it in town a gets about 11.5 mpg. The low highway mileage I was putting off to extrememely cold weather and maybe the gas blended. I'm not expecting the world but I would thing we should be better then 11.5. The truck rides on 235's, gearing is 3.27, I've cleaned the MAF, TPS is at .96v and we ran seafoam through the gas and intake. The only thing he has changed, not stock is that he removed the muffler, so all he has is the CAT's with the pipe exiting infront of the rear wheel. Could this be causing some of the poor mileage?

 

the exhaust cut off is definitaly part of the problem, you need a muffler to create backpressure so the engine can combust properly

 

bull**** i took my muffler off and second cat and my gas milage hasnt changed i have the same gears and tires and a 5spd and i get 15 city and 19 almost 20 on the highway. get a new air filter and clean your intake tube and check compression.

 

Thats not true. my buddy and i both cut the muffler off our trucks and have seen no change in gas mileage. he has a 2wd 3.0 and i have a 4.0 4wd. none the less these trucks come with 3-4 cats. they produce enough back-pressure


try doing a complete tune up on the truck. i did with mine when i was seeing 10-12mpg and now im getting about 14-16mpg. and that is with driving the same way both times.......with a lead foot.

I changed the oil and filter claened the MAF. after that i ran seafoam in the oil, vac lines and gas tank. (one can will do this. 1/3 of the can in each). i ran the truck for about 100 miles and did another oil change and filter. then came spark plugs.

after adding seafoam to the oil u have to do an oil change with-in a reasonable time. i did mine after about 100 miles. i also did an oil change before the seafoam, with some cheap oil but a good oil filter so all the crap that was in my engine plus all the deposits the seafoam loosened up would be collected. the second oil change was mobile one 5000. its like liguid gold and i swear by it.

hope this helps

Dave

 

welcome to the world of a OHV 4.0L hahaha.. best i ever got on my 1993 splash was 13 city lol..

welcome to the club..

 

i jus got home and had time to read your post all the way. but yea i did seafoam on my truck and i saw improvement.

 

I'm not expecting to get into the high teens but 15-16 would be nice. We need to try something. Those are all good ideas, just where to start spending. I'm not automotively knowledgeable, thats where I rely on the forums for direction. Could an O2 sensor or fuel filter be a problem? Is there some diagnostics that the dealer could run on it?

 

No 2 engines are machined the same. Some vehicles will never get the mileage others get and some will get great mileage. So do some cheap simple things first and see if you can get better mileage. One thing you might want to check is your brakes. Make sure they are adjusted properly and are not dragging. Check your E brake while you are at it. People tend to forget the brakes and when they start getting full of grit or one or more is out of adjustment it causes drag.

My Mom's 2003 Buick Regal 3800 V-6 is just the opposite. It gets 36 MPG on the highway. I have checked it several times and it just amazes me.

 

Just out of curiosity, how are you coming up with those fuel mileage numbers?

 

Thats what i was thinking.. with 3.27 gears, and those smaller tires.. he shoudl be getting close to 17-18 on the highway -at least- after that bit of engine tune up happened.

 

I'd scan the computer for codes.
Then I'd disconnect the battery to reset the computer.
Then I'd want to see how quickly the 02s swing. My understanding is that as they near the end of thier life they swing more and more slowly. Milage can be effected as they deteriorate.

Otherwise.. dirty valves, dragging brake, or a lead footed driver.

Rich

 

We are getting those numbers from what the trip odometer reads between fill ups and how much gas he pumps into it until the pump clicks off. As for the accuracy of the odometer we figure it is close to bang on from driving the mile roads and the GPS indicates the speedo was was right on. He has definitely eased up on the foot as gas prices are now $1.21/l or $3.96/g here. We had the rear brakes replaced when we had it safetied a few months back but I could take it back to them to check.
Mike

 

I'd just jack the truck up and spin the tires.

If that checks out & you've reset the computer. Then it just about has to be an 02 sensor or the nut behind the steering wheel.

I kid a little.. but driving technique has an awful lot to do with it. Younger people don't seem to understand that one is NOT green and the other red.

Antisipating a stop goes a long way to helping milage.
Having an instant MPG readout will make a guy realize just how important it really is. For instance.. the PCM turns fuel off when you have been decelerating for a few moments. The way my daughter or wife drives.. they never get into that mode of the pcm! They just push the gas until it's time to hit the brake. Drives me nuts!! It's not that they are driving fast.. that's my job. They just don't seem to comprehend anything beyond "go" and "stop".

This is part of the reason I can hit 20-21mpg with a 4x4 FX4 ranger w/auto tranny and 4.10 gears. Simply.. driving technique. Shoot I go WOT from 0-60 at least once a day in my 65 mile commute. Yet I still average good milage.

Rich

 

i have to same thing 3.0 4x4 auto i get 19-23mpg all the time with a mix of highway and city

 

Before I got the X-cal (which made a difference) I got a best of 22.x on a road trip last summer. (70mph w/cruise on)
I'm looking fwd to bettering that this summer now that I have a tune.

Rich

 

Aren't 3.27s really low gears for 235s? I had 4.10s with my 235s stock.

 

I have been reading lots of these posts, because I tend to have the same problem with my Mazda B4000. I drive a 2001 Truck, and my buddy drives a 2008 Ford Ranger 4.0 Ltr (essentially still the same) and he literally eats half the gas I do. Should I tune up? Or are there things I should really be looking for? I was thinking brake drag, air filter, plugs, and a good clean of all fluids?? If that doesnt work, then what should be the next thing I am looking for?

 

3.27 gears are for highway on the highway in my truck i cruise at 70 at 2100 rpm and i get right around 20 if i do a whole trip on the highway. when i do alot of city driving my gas mileage takes a huge crap and i get around 10 to 11 and when i mix highway and city i get around 17 so are you driving all city or a mix?

 

If the gears have thrown the speedo off you're calculating MPG from a tripometer that is missing some miles...

 

I have a 92 4x4 off road with the 4.0 automatic. I learned two very MAJOR things. 1st is I have to stick with only certain name brand gas for example here I use only BP if at all possible. No matter what if I buy gas from speedway or we have a cheaper company I get only the 11mpg. I can watch the gauge go down. So not matter what I stick with BP in my area. Secondly I started dumping a can of injector cleaner in my beast every week or two. It took a couple weeks to see the difference but I am up from 11 mpg to 20ish now consistantly. I use the gold or silver (for large vehicle) stuff from Waly's World and it really really has help. I may be wrong but in my truck it sure seems happier.
I helped a mechanic friend clean the injectors on my nephews ranger last winter. Just by using one can of that gunk stuff it could no way make a dent in his injectors. I think that was the reasoning I used several cans over a while. The injectors we cleaned were on a 97? 4 banger and were virtually closed up. That job wasnt difficult to do if you have basic knowledge of tearing appart and putting back together.

 

I am only getting 12.7 mpg mostly in the city. I understand about taking your foot off the gas when a possible stop is ahead but I do not understand why the PCM shutts all the fuel off. wouldn't no fuel to the engine create an engine breaking effect, shouldn't the PCM allow just allitle fuel to the engine to prevent drive train resistance?

 

Injector shutoff is designed to work with the EGR system. When you are coasting down the egr valve opens and the ecm kills the injectors. The engine runs on the unburnt gas still in the exhaust.