Buy one of these and install it in plain view.

Drive your Jeep using this info along with the gauge.

http://www.ehow.com/how_8098066_driv...-gasoline.html

 

I would think o2 sensors fall into keep up, but I know most don't think that way so it's a good point.

 

Don't bother with a vacuum gauge. Don't bother with the "Tornado". If you really want to improve your fuel economy with what you have make sure all of the maintenance items are serviced. This includes differential and T case fluids. Get a set of OEM spark plugs IIRC Champion RC12YLC gapped to .035" for the 4.0 I6. Clean the fuel system using a good cleaner like Chevron with techron. I have had good results with the 3m system (although it is expensive) you can obtain the same results with throttle body cleaner spray, seafoam, and a good fuel injector cleaner.

Don't buy into hype and BS products that promise improvements. I have tried several products that supposedly had "proven" improvements. E3 spark plugs, K&N OEM replacement filter, TB spacer, Ebay "module" that hooks on the AIT sensor plug.... none give noticeable gains. Some make the engine run bad.

Find the happy inflation pressure of your tires. Since they aren't stock the pressure indication on the sticker is not applicable. Use the grease pen method.

Change your driving habits. You need to use momentum instead of converting it into brake dust and heat. What I mean is coast as much as you can, let off the throttle just before the crest of a hill, coast to stop lights and stop signs. You will likely **** off people behind you but think of it this way... they aren't paying your fuel bill.

Join ecomodder.com and read, read, read... there are a few people on there with XJs.



If you have some money to spend there are a few PROVEN products. However keep in mind there is a chance you won't see a return of investment (ROI). This is due to the expense of the product Vs the gasoline you could have bought with the money you spent.

One is an MPGuino or scangauge II. These don't necessarily improve economy mechanically as much as they are a driver's aid. Depending on what you get now and your potential you might or might not see a ROI.

Another is the edge trail jammer system. It is very expensive and you will likely NEVER see a ROI.

 

Thanks ill look into regearing and I'm definitely planning on keeping my xj for a very long time
It's a 2000 with about 70k miles. Previous owners bought it because they had a cabin in big bear and wanted a 4x4 to get to it but It just ending up sitting in their drive way, I've put about 20k on the past 2 years I've had it manly because I drive it up to the high sierras every year

 

But that was alot of useful information thanks Razor02097

 

Geeze guys I need to figure out whats wrong with my jeep then. I am getting 9 to 10 in the city... I just installed all new sensors and cleaned the TB. Time to look at tire pressure, spark plugs, and changing fluids.

How effective is the K & N system for xj's?

 

Ehhh. It al right go for the spectre cowl intske.

 

I don't understand people posting their mpgs without even giving any advice other than "It's really how well you take care of it" and everything.

You can find many answers on Google and by searching on here, but people often suggest to check the rotor / plugs & wires / oxygen sensor / tire inflation / watch your right foot. Of course 32s don't help and is a major part of the poor gas mileage. Maybe if it's that bad save up for a re-gear (if you didn't already do that)

 

X2 on regearing. I went down about 1 mpg when I put on the 31s

I see 20mpg as unrealistic with these jeeps. I've never gotten above 18.7 and that was when I was stock.

Get some 703 injectors they're mor evicent

 

a NOS sticker will give you similar results for less money.

 

- Regear to fit your tire size
- Clean and re-assemble all electrical connectors
- Ignition system refresh with the spark plugs called out under the hood
- Emissions system maintenance including catalytic converter and O2 sensors
- New quality engine, transmission, transfer case, axle oils, all filters
- Grease everything that should be greased
- Verify brakes aren't sticking
- Verify engine accessory pulleys are smooth
- Check for vacuum leaks
- Check for exhaust system restriction
- Check for leaking exhaust components such as cracked manifold
- Verify engine compression, replace worn rings, valves, valve springs
- Clean fuel system
- Clean combustion chambers
- Test and verify all fuel management sensors such as TPS, CKP, CMP, CTS, IAT, MAP, BTS
- Verify that speedometer is correct
- Check fuel system for leaks
- Adjust tire pressure

^^^ This is all a "tune up" on most XJs to restore them to factory specs, and still isn't a complete list ^^^

You can also...

- Install high-flow cold air intake (a real one)
- Install high-flow exhaust
- Upgrade fuel injectors
- Relocate IAT
- Eliminate clutch fan

- Lower your XJ
- Remove the large, heavy tires
- Remove heavy off-road equipment
- Drive sanely
- Install a diesel
- Convert to 2WD


This has been covered about 800 times, do a search and you will see some more in-depth discussion if interested.

Better... NOS sticker is waterproof!

(Surprised you didn't re-post your Toyota Camry DD cost-savings analysis! I love that thing)

 

City or highway driving? For hwy, get 4.10/4.11 gears and for city get 4.56 or 4.88s. The deeper gears will turn the tires more easily saving both gas and tranny life if you're not stupid.

 

Really?? The best I've gotten was 31, that's thirty-one, mpg. 30mph tailwinds and flat Minnesota highways may have helped...

Otherwise I used to get 16-18 gong back and forth to school and then mid 20s for long highway trips, all on 31" ATs. How's your exhaust manifold look? Cracked?

 

Lol there's no way a 4.0 xj could posibly get 31 mpg I might belive 21-24 on flat land with a tail wind and the cruise set at 60.

And in the words of the great forrest gump

"That's all I gots to say about thayat"

 

And how many of those parts were new versus 15 years old and worn out? Best my 1999 5-speed 4.0 has seen was 28 MPG driven properly on the highway, stock speedo, tires, and gears. Bunch of other people with similar configurations have gotten the same.

How you drive and how you maintain has everything to do with economy.