Jeep Wrangler Forum banner

20 mpg on my tj!!!

13K views 104 replies 44 participants last post by  ChaddG 
#1 ·
I cleared the adaptive memory, went through the 50 starts in 200 miles, filled up with premium, and got 20 mpg!!!!! :eek: I only ran the tank down the first 5 gallons. got 100 miles to those 5 gallons. :thumb:

I lost the thread, here is how I remember it going.
disconnect the + battery terminal,
touch the + terminal to the - terminal,
turn the ignition on,
turn the lights on,
turn them off,
turn the ignition off,
reconnect the + terminal.
 
#35 ·
Anecdotal. I've done the same thing and it's not an accurate representation of your actual fuel economy. Test it again, only this time over a period of, say, 30 days. 30 days of normal driving. Fill it up completely before you start the test, and fill it up at the completion of the 30 days. The longer the testing period, the more accurate the results will be.
 
#36 ·
I got 22 with my stock tj (4.0, 32rh, 3.07s, no top, doors, or back seat) running about 45 rural cruising, few stops, long trips. I now get 15 average on 33s. No magic for fuel efficiency, just physics and driving habits :thumb:

Anecdotal. I've done the same thing and it's not an accurate representation of your actual fuel economy. Test it again, only this time over a period of, say, 30 days. 30 days of normal driving. Fill it up completely before you start the test, and fill it up at the completion of the 30 days. The longer the testing period, the more accurate the results will be.
I suppose you mean more miles traveled/fuel used, the more accurate. What if he only used half a tank in those 30 days? :rofl2:
 
#37 ·
I did not do the procedure 50 times, I only did it once.
I just started and shut down 50 times within 200 miles after doing it.
I am still getting close to 20 mpg. 65 miles on a quarter tank.
I always count my gallons from the top of the tank, Fill up. Drive,
on refill I divide the miles by the gallons.
I keep my tank full.

Jgorm, I'm not here to waste my time arguing. This is what I did, and here are the results.
waterdog, I ran the gallons from the top of the tank, yes.
shadydc, I calculated my mileage after,
<filling up, driving 100 miles, then filling up again.>
I am not telling everybody to do this to their jeep. I merely tried the thread I read and gained a few mpg since I have done it.
You guys are all grown adults and have the free will to do whatever the heck you like.
I don't feel bashed, I don't mind clearing up any points I was unclear on.
I am only doing my blogging part and spreading the good news.
I had positive results on the thread I read about resetting the adaptive memory.
The results were clear to me.
I did it one time,
I drove my jeep for 200 miles, making sure I had 50 starts in there somewhere, and made sure that the temp guage read at least to the first hash mark when I drove it.
My day is this,
take one kid to school across town. come home, shut down.
20 min later, start up, drop the other one off 1 mile away. come home, shut down.
Start up, drive a mile, go to youngests school, shut down for a while, wait. Start up.
Drive across town to pick up the oldest and go home, shut down.
Start up later at night, go to work. 10 miles highway, shut down.
Start up, go home, 10 miles highway, shut down.
Repeat.
So I easily got 50 starts within 200 miles.
I did not repeat the whole 1-7 50 times, only #7. My bad on the wording.
I hope anyone else who decides to try this has great results.
 
#40 ·
I could see helping, your not fooling the computer. Just relearning driving habits, starting with a fresh sheet. And if you change your habits to what he is doing, your mileage would probably improve with out flashing the computer. I would think most benefit would be with an automatic.
 
#43 ·
Yeah but if you stand there forever and keep pumping fuel in like I have done before it looks better on paper. LOL My 15 gallon tank was at 1/4 and I managed to squeeze 14 gallons in it late one evening when there was not much going on. Basing "only" off the gauge and odometer I got 93 miles on a 1/4 tank of gas. If I calculated like that, then I got 24.8 MPG at that time!!! I would only ever use that calculation with a wife (if I had one) to argue why the Jeep is good to drive when it comes to fuel mielage.
 
#42 ·
I smell something Bogus... sorry.
 
#44 ·
The sad fact is that if the passenger side of the Jeep is up an inch higher than the driver side, you can trap an air bubble 2.5-3 gallons in size on the high side of the tank. The filler neck is on the left side of the tank, and as soon as the liquid reaches the bottom of the vent tube, a pressure spike shuts off the gas pump.

You said you were getting 13mpg. If you filled it at a station where the Jeep was tilted, and there was 2.5g of trapped air, you used 7.5g in 100 miles, for 13.33mpg.

That is what I believe. Try measuring mileage over a longer period like 3 tanks of gas. When you fill up the first and last tanks, put your weight on the passenger side of the bumper and "burp" that air bubble in the tank. That way you get a consistent fill instead of a random shutoff.
 
#45 ·
The sad fact is that if the passenger side of the Jeep is up an inch higher than the driver side, you can trap an air bubble 2.5-3 gallons in size on the high side of the tank. The filler neck is on the left side of the tank, and as soon as the liquid reaches the bottom of the vent tube, a pressure spike shuts off the gas pump.

You said you were getting 13mpg. If you filled it at a station where the Jeep was tilted, and there was 2.5g of trapped air, you used 7.5g in 100 miles, for 13.33mpg.

That is what I believe. Try measuring mileage over a longer period like 3 tanks of gas. When you fill up the first and last tanks, put your weight on the passenger side of the bumper and "burp" that air bubble in the tank. That way you get a consistent fill instead of a random shutoff.
Getting 20 MPG is a daily occurance for me. lowest I get is 18 with 33x10.50 3.5" RE lift 4.10 gears

I mesure my MPG on every tank. Ive checked my speedo via friend who is cop with laser dead on, mesured my odometer with GPS also good, Did 100 mi trip and gps read just under 99.6. its all about how you drive your jeep and the weight its pulling.
 
#46 ·
My stock 2000 Sahara got 20 MPG at 160k miles. It now has a zone 4.25" with 33's and gets 15 MPG on the highway using cruise. I think some of you are just horrible at math. For one thing check your F&*^ing speedo with a good GPS. I was nuts on with stock tires but am now off by 4 MPH at highway speed.
Do you have any idea how much that effects your indicated MPG you nitwits?
If I drive from Eugene to Portland which is 106 miles it will only look like you went around 95 miles on the trip odometer.
Top off your tank only till the pump pops and do the same when you top off again(+/- half gallon if your level)
Divide your CORRECTED milage(if you have oversize tires) by how many gallons it took to top it off.......and keep it within a tenth gallon....it matters.
Do this a few times and you will get your actual MPG.
I get 14.5 MPG if I cruise at 70 MPH on relatively flat terrain for the 106 miles.
Yes TJ's get terrible MPG but you re re's are making it look a lot worse than it is.
 
#51 ·
jefferyc22 said:
My stock 2000 Sahara got 20 MPG at 160k miles. It now has a zone 4.25" with 33's and gets 15 MPG on the highway using cruise. I think some of you are just horrible at math. For one thing check your F&*^ing speedo with a good GPS. I was nuts on with stock tires but am now off by 4 MPH at highway speed.
Do you have any idea how much that effects your indicated MPG you nitwits?
If I drive from Eugene to Portland which is 106 miles it will only look like you went around 95 miles on the trip odometer.
Top off your tank only till the pump pops and do the same when you top off again(+/- half gallon if your level)
Divide your CORRECTED milage(if you have oversize tires) by how many gallons it took to top it off.......and keep it within a tenth gallon....it matters.
Do this a few times and you will get your actual MPG.
I get 14.5 MPG if I cruise at 70 MPH on relatively flat terrain for the 106 miles.
Yes TJ's get terrible MPG but you re re's are making it look a lot worse than it is.
You're right about speedometer accuracy, but to be accurate in your inaccuracy, your speedometer isn't simply off by a certain MPH, it's off by a percentage. The faster you go, the farther it's off. For example, when you're at a dead stop, your speedometer is exactly accurate @ 0 MPH.
 
#52 ·
Ive been filling up with 87 and I replace my air filter with K&N intake and i average about 12 mpg. When I got it the deal said about 17 city mpg.
 
#53 ·
Jerry Bransford said:
The parking area next to the pump isn't made from poured concrete? :confused:
Of couse it is. Doesn't mean there isn't a slope. I'm surprised you didn't know this- concrete can be poured on a slope. For example, here's my driveway. If you want, I'll stop on my way home in a bit and take a pic of the station where I usually buy gas.;)

 
#71 ·
Of couse it is. Doesn't mean there isn't a slope. I'm surprised you didn't know this- concrete can be poured on a slope. For example, here's my driveway. If you want, I'll stop on my way home in a bit and take a pic of the station where I usually buy gas.;)

http://s285.photobucket.com/user/67CJ5/media/100_2912.jpg.html
In my previous life I worked on construction crews building gas stations, the dispenser pads are built flat +/- 1% any fall greater than 3%ust have a grated containment basin.. Most all sights opt for flat..
 
#54 ·
I see that no matter what is said, there will always be a non-believer, the guy who always has to rationalize that what you have proven is wrong.
Sad guys. very sad.
To those who support the fact that it can be possible, or that it has happened.
congrats! and Thank you.
To those other guys.... I can't change a mind that is already made up. Please take your negativity and destructive criticism somewhere else.
Thank you.
 
#55 ·
I see that no matter what is said, there will always be a non-believer, the guy who always has to rationalize that what you have proven is wrong.
Sad guys. very sad.
To those who support the fact that it can be possible, or that it has happened.
congrats! and Thank you.
To those other guys.... I can't change a mind that is already made up. Please take your negativity and destructive criticism somewhere else.
Thank you.
Get back to us with the tech and proof of why this works and we will believe you.




As far as level vs non level gas stations. Around here it's mom an pop stations so flat concrete. Sheets is flat with drains. I have seen them with the Crete laid to allow water runoff however. Like most garage floors and concrete or even asphalt driveways.
 
#56 ·
I've gained 3-4 mpg average over 10 tanks of gas with a k/n air filter.
I am sure warm weather has a lot to play on mpg.
I am only running premium through this tank and maybe one more for information on how many more or less mpg can be got for my extra .40c / gallon.
I will also try days of nice driving, compared to beating the crap out of it.
I've put 3500 miles on since Jan. 1st. I have been tracking fuel consumption since I got it.
I should start a graph....
 
#62 ·
This thread has so much BS! A cai is not going to get you any mpg. I have tons of mpg data from before and after my cai and there is no difference. Using the gas gauge is a total waste of time for calculating mpg! the only thing that is legit is that if the ground is not perfectly level, it can alter how much gas goes in the tank by a few gallons. I notice this at a lot of the stations I go to. A couple degree slant will affect how much it takes. I have 72 gas tanks worth of data so far including the top I was using, trip miles, odo, scan gauge data, tires, etc.
 
#63 ·
Even on flat ground, I have to pay attention to how much I get in the tank. Some dispensers shut off sooner than others, and either way I can put a lot more fuel in the tank after the auto shut-off. If I run the nozzle really slow, I can fill it right up to the filler neck, and even over flow it if I'm not careful. Now I'm curious about just how much slope there is at my normal station, but it's quite a bit. Maybe I'll throw the angle finder in the Jeep next time I need fuel just to try to get a general idea.:)
 
#64 ·
Back in my high school service station working days, I remember a couple of guys who drove trucks with service beds on them. They carried a 4x4 block around with them and they would toss it down and drive the left rear tires up on it so they could cram as much fuel in there as possible :rofl:
 
#65 ·
I can't help but wonder why half of you guys drive a TJ if you are obsessed with MPG.

Let's face it you're driving something with all the aerodynamics of a brick. If you want high MPG, buy a Prius.

Oh and By the Way, think yourselves lucky you don't live over here where petrol is over $9 a gallon.
 
#66 ·
I'm not obsessed with it, and in fact I think the mileage I do get is pretty respectable, all things considered. I do check my mileage almost every fill up though, because I want to know. If it's suddenly dropped, I want to know if there is an issue. Besides, I can afford the ~10 seconds it takes to check it..;)
 
#67 ·
I'm not having a go at any individual. It's just that there are so many threads on here about MPG. Whilst I agree that it can be an indication of a problem, it generally has to be a pretty drastic change to do that.

I just accept that my TJ drinks juice like it is going out of fashion, but I completely enjoy the experiences that I have using the fuel that other people's Prius' save.
 
#69 ·
I got infinity MPG when AAA towed my jeep under my parents' policy.
 
#72 ·
I agree.....I'm 19 and my fuel reading that I get from my scan gauge tells me I can get about 28 MPG on the highway. Now I know this is incorrect (people have suggested because I am using a Canadian Gallon or something like that.....i'm from AUS so I have no idea about Gallon's. I work in litres)

I have 35's with a 4.5 inch lift.....not sure if PO previously regeared. I think ge did due to the revs I actually get on the highway.

My point: I drive my TJ and love it. If I drive to work in it or if I drive it out bush I love it....I fill it up when the indicator tells me its nearly empty and that's that. No matter what you're getting I think we can agree on one thing.....we drive saaweeeet cars
 
#86 ·
It must have been a lucky week when I got the 20 mpg, conditions perfect.
this tank is getting 17 mpg combined cty hwy
the temp has dropped 40 deg.
windier then chicago,

Here is a thought, why doesn't one of you let me use their computer to catch appropriate mpg?
I will do a study of things I do and record the results.

I only use one gas station, about a mile from my house.
Very level

I know my mpg will not stay at 20, unless all the roads are flattened, wind only blows behind me, the temps stay in the 65-80 range, and no parts wear on my jeep.
I will try replacing the 12 year old o2 sensors too. I am kinda scared to though, that whole if it isn't broke don't fix it thing.
 
#87 ·
And we realize that any jeep with a "15 gallon tank" really has a 19 gallon tank with and extended filler check valve to keep it at 15. Yes, Jeep sold that upgraded capacity for a markup and only had to swap filler check valves. I have a 15 gal tank so i always have an air pocket!

My 4cyl with 33" tires, 4.10's constantly gets 18, today's fill up showed 20. I check every tank, every time. I always fill all the way up and after the click of the pump going off, run it again until it clicks off again, usually another .5 gallon.

From that point I can drive (like this week) 232 miles until I fill up again, same procedure. And even though the gauge is as low as I dare to let it get, it never takes more than 11.5 gallons in my 15 gallon tank.

Moral of the story is, buy a Volt (GO 'merica!)

Also, there is a switch over of winter blend fuel to summer blend in the swing climate states, and if they are selling winter blend, and you have an unseasonably warm week...you will get better MPG's....throw that into the calculations....
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top