A jeep running stock gear and 33" tires while in overdrive will not let the engine rev to its optimal rpm range (sometimes called the power band). Driving in 3rd will put the engine closer to this range when at highway speeds. After I installed my lift and bigger tires I drove my XJ for over 4 years and never used overdrive. Saw about a 1-2 mpg improvement over when it was stock.

 

The best fix for terrible gas mileage is to get rid of the slush box we call the AW4, so much power is lost in old auto transmissions. I notice my GF's jeep (01, AW4 3.5" and JK 32's) loves to keep the rpms between shifts well above 2K till you get up to 50 or so. My 95 on 33's, 4.5", AX15 and 3.55 gears gets 16-19 mpg all day everyday. I barely rev it over 2K and while it may be slow, it goes and goes. With gas prices now, i wish i kept it 2wd, just alittle bit

 

Will a new ish aw4 bolt on to my 92 motor?

 

x2 for my 89.

 

touché haha

 

Put stock tires on her and see if that makes a difference. If you put 3 tanks of gas in it in 1 week then you either drove hell of a lotta miles, lost a lot of gas via leak or plain burned through it...

 

I just saw that this product is installed in my jeep.....wonder how it would react with it disconnected?

http://www.gforcechips.com/jeepcherokee.aspx

 

id disconnect it there a scam all they are is a resistor that tricks your ecu i dont think there a good idea at all

 

http://www.resellerratings.com/store...formance_Chips

 

I read other reviews lol i feel the same way im gonna un install it tomorrow

 

Ok so I uninstalled it and I feel it runs better! I had time yesterday and changed the oil and cleaned both the air filter and TB which were filthy!!!

 

FINALLY!!!!

I finished the full tank of gas and the total amount of miles was.........180!!!!
WTF?!?! I used seafoam, cleaned the air filter and changed the fuel filter!

Now my question is since im running 33's did i actually travel more than 180? If so what would be a closeestimate of what i drove?

 

I don't get why these performance chips don't work with out straight 6 jeeps. From what I understand they work amazing on diesels

 

http://go.jeep-xj.info/HowtoSpeedoGears.htm
Read that. Your speedo is definitely off with 33s. You traveled a bit farther than that. There's a calculator on that site that will allow you to get a more accurate number than that.

And by full tank, did you fill up 20 gallons? That's seriously what you're gunna get on 33s and stock gears (ask me how i know). And have you checked to see if your exhaust manifold is cracked yet?...................

 

Anyways, you wanna talk about frustrations when not seeing improvements after repair/maintenance? I got my XJ back in September of last year. When I first got it, I was getting roughly 11 MPGs. It's been about 6 months and while I've had it, I've done a tune up (spark plugs, wires, distributor cap, rotor), fuel filter, oil and oil filter, put in a K&N intake, coolant temp sensor, thorough throttle body cleaning, new IAC, new TPS, all new fluids (coolant, differentials, transfer case, transmission), transmission filter, new catalytic converter (old one was clogged/broken internally), new o2 sensors (upstream and downstream), as well as countless other repairs. Guess what mileage I'm getting after that? Still 11. 12 on a very rare day.

Moral of the story, if you want a noticeable improvement, re-gear, throw on an entirely new exhaust system (from headers back), and remove anything restricting aerodynamics (roof rack, etc). You're driving a flying brick. It is what it is.