Blue88Comanche Posted June 16, 2011 Share Posted June 16, 2011 What are some ways to improve gas mileage on the 4.0? Just a general chat/question if someone found a gas saver that works. I get about 19.5 to 20 mpg Link to comment Share on other sites More sharing options...
Comanche County Posted June 16, 2011 Share Posted June 16, 2011 19-21 is good. It can do better if you alter your driving habits. Do a search for "hypermiling" or "hyper-mileage". I don't back up all of their methods like minimal braking around corners, etc. But this stuff works. When I worked in CO I'd coast down 6 miles of mountain road with the engine off every morning at 4 am. Turned my 23 mile commute into 17 miles. I could only do that because there wasn't other cars on the road at that time. I'd never do that in traffic. http://www.gasolinecreditcards.com/ecot ... resources/ Link to comment Share on other sites More sharing options...
terrawombat Posted June 16, 2011 Share Posted June 16, 2011 Gas mileage will vary heavily depending on the season. In the winter I can barely muster up 17-18MPG on the highway with my '01XJ. In the summer, that same Cherokee will get 20-21MPG (with A/C off). You're not going to be able to make our bricks more aerodynamic so that really limits good fuel mileage to driving habits. I have found that if I keep my XJ in the 65-70MPH range on the highway, I will net better fuel mileage than if I stay in the 70-75MPH range - most likely has to do with the RPM I'm running at and where our 4.0L engines are their most efficient. Something else I've tried, but haven't really seen noticeable results, is to air up your tires a few PSI more than the recommended amount. Link to comment Share on other sites More sharing options...
dakal Posted June 18, 2011 Share Posted June 18, 2011 i also tried the few more air in the tires. didn't seem to make a difference. wish i got 19 mpg. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted June 18, 2011 Share Posted June 18, 2011 let's face it...it doesn't even matter for me. i don't have the self control to stay out of the skinny pedal. i figured mpg out on my '99 xj, though...19mpg hitting the rev limiter in 1st and 2nd gear. guess it can't get that bad. Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 18, 2011 Share Posted June 18, 2011 4.6 Hesco stroker, AW4, 31" tires, 4.09 gears. The Good: On a long trip, it drones down the Interstate at 75MPH / 2500RPM happy as hell and delivers 21MPG minimum, most of the time closer to 23MPG depending on the weather. The Bad: Around town, which is at least 75% of it's use, careful or not w. the skinny pedal, best possible is 15MPG, but usually it's 13MPG. And have been recording MPG for almost five years now. So screw it, I'm not careful w. the skinny pedal anymore and enjoy it locally. :cheers: Link to comment Share on other sites More sharing options...
Automan2164 Posted June 18, 2011 Share Posted June 18, 2011 Just filled up the ZJ today. 5800 LB wet with 30's a 4.0L. With my grandpa driving style, liberal use of cruise, and coasting, I have a confirmed mileage of 20.26 MPG for the 414 miles I got out of that tank before filling... 100 miles of that was with trailer. Rob :D Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 18, 2011 Share Posted June 18, 2011 Just filled up the ZJ today. 5800 LB wet with 30's a 4.0L. With my grandpa driving style, liberal use of cruise, and coasting, I have a confirmed mileage of 20.26 MPG for the 414 miles I got out of that tank before filling... 100 miles of that was with trailer. Rob :D 20.26 MPG confirmed on one tank of gas. Freaking amazing! Ever check indicated vs. GPS? Just curious................. Link to comment Share on other sites More sharing options...
Automan2164 Posted June 18, 2011 Share Posted June 18, 2011 I use the same pump every time I fill, only fill until it clicks off, no topping off. Then I use the amount filled vs the trip. I wish I could trust the average MPG calculator on the over head console, but I don't. Simple math it is. I do watch the instant MPG though to keep my driving habits in line. Rob Link to comment Share on other sites More sharing options...
terrawombat Posted June 18, 2011 Share Posted June 18, 2011 I would kill for that kind of mileage in my ZJ. But then I'd have to swap out the 5.9L for something a little more...practical Link to comment Share on other sites More sharing options...
Jeepman Posted June 18, 2011 Share Posted June 18, 2011 In my opinion and first hand experince the best things would be - Look at your gears to see if they are correct for your tire size and if not re-gear - Electric Fan swap to get rid of the Mechanical fan - Open element filter and better flowing exhaust - Hub Conversion IF you do not already have the Vacum actuator - Synthetic fluids - Tonneau cover for us MJ guys - Mid grade fuel - Vacum guage so you can monitor your driving My MJ with a slightly moded 4.0L (but nothing major) and the electric fan, AW4, 3:73 gears and 31x10.5x15 tires gets around 15L per 100KM (15MPG) city and I am not nice with it, I do not drive all that much with it on the highway so I will have to look that up next time I am on a Road trip... It will get much better once I get my 33's on as my gears are too tall for 31's and get around to installing my Hub conversion... I find it soo funny when people make statements that the Jeep can not be good on fuel because it is a brick in the wind, Fuel mileage is what your make it and it can be great if you make the right changes and drive acordingly but most people do not spend the money in the right places especially once they have lifted the Jeep... My Old CJ7 on 35's with the right amount of things done and the correct driving attitude I got around 600KM per tank (19MPG) so the brick in the wind is definately not a a good statement... Link to comment Share on other sites More sharing options...
dakal Posted June 19, 2011 Share Posted June 19, 2011 not a highjack! i am replacing my exhaust and the inside of the pipe is totallly black. everything is correct, so i'm going to try making the adjustable map sensor. its featured on two of my bookmarks. a friend of mine has good luck with his. anyway will post when i have more info. dave Link to comment Share on other sites More sharing options...
Sir Sam Posted June 19, 2011 Share Posted June 19, 2011 Drive better: And yes I double check by hand calculated, the mileage from the OHC is dead on for me. Link to comment Share on other sites More sharing options...
cody4359 Posted June 21, 2011 Share Posted June 21, 2011 get a commuter and don't worry what the toys get for mpg. went from 10-15 mpg in my xj to 27-34 mpg in my GLI :jump: Link to comment Share on other sites More sharing options...
mvusse Posted June 21, 2011 Share Posted June 21, 2011 When I still had Booger, best ever mileage I managed to get was 22mpg. The new owner was putting 1000 miles a week on it between getting a job in Maryland and finally getting his house in Ohio sold, so he started fuel saving modifications, including different fuel injectors (from a Neon, I believe) and putting skinnier tires on it. He's going down the highway getting 26mpg now. That's in a 94 4.0HO. Link to comment Share on other sites More sharing options...
Jerry Posted June 21, 2011 Share Posted June 21, 2011 This is a handy little app if you have an android phone. Just plug in the numbers every time you fuel up :thumbsup: https://market.android.com/details?id=ch.simonmorgenthaler.fuellog&feature=search_result Says I'm getting 20.4mpg Link to comment Share on other sites More sharing options...
Donkey Posted June 21, 2011 Share Posted June 21, 2011 these 4.0 are getting better mileage then my 2.5 i got 20mpg my first fill up. however do you think if i go to 4.10 gears ill get better mileage, supposedly someone swap a 3.55 axle in to it before i bought it. Link to comment Share on other sites More sharing options...
MJCrusader Posted June 22, 2011 Share Posted June 22, 2011 The math shows I get about 13.5 mpg which breaks down to about 70/30 city to highway driving. I do need to figure how to calculate my bigger tires though. I've got 31s on the truck, so I guess I'm actually getting about 14.5 or 15mpg. Not bad for me seeing as how my previous truck was a Chevy 3500. I'll take 14mpg over 6mpg any day. Link to comment Share on other sites More sharing options...
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