better gas mileage

[99xjmud]

sure this has come up, but it seems that i don't get good gas mileage. are there any inexpensive ways out there to get better bas mileage? like additives i can get at wal mart that you guys swear buy or anything like that. i do plan on gettin a k & n replacement filter when i get some money. not enough for the generation two though. thanks

[ChadYJ92]

Re-gearing is the best option. Otherwise there isn't much to do:

Check your tire pressure
Make sure you have good spark plugs

I can't think of anything else, and I personally would not put any additives in my gas or oil. Its just snake oil.

[tazman]

I hear that a throttle body spacer tends to help in that a bit

[DeckSetter]

has anybody tried one of those MSD igition boosters? They're supposed to burn your fuel more completely for more power and better efficiency. With a hotter spark though I can't help but wonder if it would make the 4.0L run even HOTTER...

[ChadYJ92]

I don't think that the ignition booster would do much, but I have never tried one, so I could be wrong. When I think about it, can a hotter ignition really do anything? As I understand it, once some of the fuel in the combustion chamber ignites, all of it will, regardless of spark intensity.

I'd be suprised if the 4.0 ran hotter with the MSD. Its supposed to run hot, and I'd bet that the cooling system could handle a hotter spark.

[RJ]

yes i desperately need a way to get better fuel consumtion, i get about 10 to the gallon

[ChadYJ92]

I'm getting about 12 mpg right now. I am going to try to get 4.10 gears. Thats the best bet.

[WagoneerXJ]

Here's a suggestion, and it doesn't cost any $$$$$. Try to haul around as little as possible in your Jeep. I've seen people with all kinds of things stashed away in their vehicle for no reason. Less weight = more MPG [img]icon_smile_wink.gif[/img]

Originally posted by WagoneerXJ:
Here's a suggestion, and it doesn't cost any $$$$$. Try to haul around as little as possible in your Jeep. I've seen people with all kinds of things stashed away in their vehicle for no reason. Less weight = more MPG [img]icon_smile_wink.gif[/img]

Those are wise words. [img]graemlins/icon_beerchug.gif[/img]

[99xjmud]

i don't know about gearing. the 4.10 gearing you say will give better gas mileage? will you loose power, acceleration, or top speed will you regear? what are the current gears in the xj, and how much does it cost to re-gear?

[ChadYJ92]

Im not sure what the gears are in your XJ. I found out by letting my jeep roll backwards. I counted how many times the driveshaft rotated for one rotation of the tire. The shaft rotated just over 3 times, so I have 3.07 gears. Since I am now running 33 inch tires, these gears are way to high, and do not have nearly enough leverage to push the increased diameter of the tire around. This also puts the engine out of its power band, so you lose accelaration, gas mileage, and top speed (even though it is a higher gear, my Jeep simply doesn't have the power to go maintain a speed much higher than 60 mph).

When I put in 4.10 gears, the driveshaft will rotate about 4 times per spin of the tires, giving me more of everything I need.

To regear your existing axles would probably cost around $1000 for parts and labor. And this is definetely not a do at home project.

However, when I re-gear, I plan on using a Ford 8.8 rear end and a D30 with 4.10 gears, so it should end up cheaper this way (plus I get a strong rear end).

[JC]

Originally posted by 99xjmud:
i don't know about gearing. the 4.10 gearing you say will give better gas mileage? will you loose power, acceleration, or top speed will you regear? what are the current gears in the xj, and how much does it cost to re-gear?

You might lose some top end, but it'll be way above Interstate speeds. Speeds no Jeep should go. [img]icon_smile_wink.gif[/img]

If you've got a stick 4.0L XJ, your gears are most likely 3.07s. If it's an auto 4.0L XJ, most likely 3.55s. Towing package would change that, but it's only available on the auto in the later years from what I've read.

[Montana]

hi

[GRN MTN XJ]

I've got a 5 speed tranny 4.0L XJ that came with stock 3.07's. I regeared to 4.11's and threw a posi-traction in the rear diff all for around $750. But that is just parts cost, 3 days under the jeep, someone remind me to never do gears again please. as far as results, i guess i got it all put back together correctly (had only a small pile of "extra" parts, but that's good right?...) with 32x11.5's and 3.07's i was goin to fourth gear all the time on the interstate, boggin way down. now with 4.11's i cruise up hills at 70mph no problem, 5th gear at 2600rpm. the jeep now smokes most cars up to 40mph off the line, even with mud meats. gas milage is now 16 on the highway, 12 around town, stop and go. as mentioned before you do probably loose some top end speed, but that would be with stock tires. with the bigger tires, regearing brings it closer to stock tire/stock gearing performance.

[2 Jeep John]

I did a scientific measured milage (not using the speedo) test yesterday.

I have a 2002 Wrangler Sahara, 4.0L Auto Trans, 2" lift, with 32X11.50R15 on 8" rims and a hard top.

I got 17.6 miles per gallon 87 Octain. Mixed stop/go and highway.

[JLANE99XJ]

Originally posted by JC97XJ:
</font><blockquote>quote:</font><hr />Originally posted by 99xjmud:
i don't know about gearing. the 4.10 gearing you say will give better gas mileage? will you loose power, acceleration, or top speed will you regear? what are the current gears in the xj, and how much does it cost to re-gear?

You might lose some top end, but it'll be way above Interstate speeds. Speeds no Jeep should go. [img]icon_smile_wink.gif[/img]

If you've got a stick 4.0L XJ, your gears are most likely 3.07s. If it's an auto 4.0L XJ, most likely 3.55s. Towing package would change that, but it's only available on the auto in the later years from what I've read. </font>[/QUOTE]what speed is that? if i want i might hit the governor on occassion, how fast is that? my speedo stops @ 110 mph i think.. [img]graemlins/icon_beerchug.gif[/img]

If anyone is really looking to get better MPGs they should lay off that skinny pedal a bit..
other than that their are some power mods you can make but none i've heard of can significantly increase MPGs

[Steve95ZJ]

Well first off all of the fuel will only burn if there is oxygen for the chemical reaction to take place. The trick is balancing your air and fuel mixture, if you can get that perfect (which is impossible, due to too many variables) then your gas milage will sky rocket. So really the key is making sure your ride is in good shape, right before the lift and tires the ZJ was running at 16mpg in the city and 18-20 on the highway with spikes up to 24-25 [img]graemlins/jawdrop.gif[/img] . Basically we have a generation II (2 years old) with just cleaned filter, Gibson cat-back (2years old), new ignition wires, relativly new plugs (2years old), mopar PCM (2 years old), new cap and rotor (6 months old), and had just replaced the cat with a racing cat (old one was shot), just recently new fuel pump (old one was shot). Gas milage was at like 10 to 12 right before the new fuel pump and filter. Basically if seems to me that if you reasonibly try to improve performance and take really good care of your vehicle and maintain it properly the mods will bring better mpg, but only if you maintain your Jeep properly and throw in a better part here and there. [img]icon_smile_wink.gif[/img] this is just my opinion maybe I'm wrong, but its what I've come to conclude.

do I get the assclown award for this one?

[ April 01, 2003, 07:20 PM: Message edited by: Steve95ZJ ]