Bad gas mileage

Sorry to hear that, seems like a pita. That's a different header style. XJs and early TJ's have a 6 into one vs the later TJ/LJ 6 into 2. I added a flat stock brace to a un-used bolt hole on the PS of the motor by the oil pan. I am hopeful this will help prevent cracking the header. From what I have read the XJ and early TJ header of choice has the small accordion flex sections and its still recommended to brace the PS exhaust to the motor.

Not saying mine wont end up cracking, it may, its only been on for around 8 months.

What header ended up working for you?
The Banks is the best design header that I found and continue to warrantee when they crack. Hopefully this newer style to accommodate the 4 O2 sensors is less prone to cracking.
 
Currently my 2003 is only getting 10 mpg. It is a 4.0 auto with a 3 inch lift and 31 inch tires. Are there any common reasons why I’d be getting bad gas mileage?
Heavy foot will always use more fuel, if your o2,s were that bad you would throw a code or two.
Try an economy run driving it like a Yummy Mommy in a Kia, get a full tank as many clicks as you can stand! re fill again at any point as many clicks as you can stand! and check mileage to gallons used and then drive it as you normally do, re fill at any point and check mileage to gallons again. :)

If you had a carby and looked inside as somebody else hits the gas hard you would see that more gas pedal means more fuel used plain and simple its just you cant see it "guzzling" with injectors :)

If your tailpipe has black soot you are running "Rich", stick ya finger inside the tailpipe to look for the soot, (when its cold of course) lol because 10mpg without a very heavy foot will either come out your exhaust as black smoke or run past your rings into your oil.
 
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You're undergeared, ESPECIALLY that you have the 42RLE automatic whose .69 Overdrive ratio drops the engine rpms by 31% once you're at cruising speed. With stock axle gears that means your engine is lugging which can really affect/decrease your mpg.

When I regeared to 5.38 for my 35" tires and 42RLE transmission my mpg went from sub-12 to 14.6 mpg. For your 33's I'd regear to 5.13.
Interesting.

Out of curiosity, what was your RPM at 65ish like after you regeared. I'm around 2000 at 65 or so with the current setup and it DOES feel like it doesn't enjoy it.

EDIT: That would also explain why my father is getting considerably better mileage with his identical setup (with the 5 speed manual)
 
You're undergeared, ESPECIALLY that you have the 42RLE automatic whose .69 Overdrive ratio drops the engine rpms by 31% once you're at cruising speed. With stock axle gears that means your engine is lugging which can really affect/decrease your mpg.

When I regeared to 5.38 for my 35" tires and 42RLE transmission my mpg went from sub-12 to 14.6 mpg. For your 33's I'd regear to 5.13.
@Jerry Bransford how reliable is a front Dana 30 with a locker and the 5:13 gears. I know the pinion gear would be small.
 
@Jerry Bransford how reliable is a front Dana 30 with a locker and the 5:13 gears. I know the pinion gear would be small.
The pinion isn't the problem when you get to larger tire sizes like 35's, it's the axle shaft ears that hold the axleshaft u-joints. Replacing the front axle shafts with 4340 shafts like from Revolution Gear is strongly recommended for 35's and a locker. Once I did that with mine no more breakages even on very tough rock crawling trails.

My Dana 30's factory stub shaft ears cracked/broke with 35's and a locker.

@Chris I tried unsuccessfully to post a photo here 5-6 times. It showed the name of the photo, gave no link to post it full size or thumbnail, and clicking on the name of the photo took me to an unrelated forum thread.
 
The pinion isn't the problem when you get to larger tire sizes like 35's, it's the axle shaft ears that hold the axleshaft u-joints. Replacing the front axle shafts with 4340 shafts like from Revolution Gear is strongly recommended for 35's and a locker. Once I did that with mine no more breakages even on very tough rock crawling trails.

My Dana 30's factory stub shaft ears cracked/broke with 35's and a locker.

@Chris I tried unsuccessfully to post a photo here 5-6 times. It showed the name of the photo, gave no link to post it full size or thumbnail, and clicking on the name of the photo took me to an unrelated forum thread.
This one?
dscf0048witharrow-jpg.jpg
 
Thanks I have replaced one stub shaft and inner axle (short side) when I originally geared and put the locker in I was planning it on staying with 33’s but have moved to 35’s. I lost a snap ring on dishpan Monday and the cap came out on the freeway. Do you recommend the revolution axles with the 760 or 1310? U-joints? I am running Dana 30 on 35’s, arb, with 4:56 gears and automatic. What are your thoughts on the revolution gears? They are local to me.
 
I replaced the o2 sensors and I also recently replaced the spark plugs. I am still only getting 10mpg. Any other ideas of what might be causing this?
 
I replaced the o2 sensors and I also recently replaced the spark plugs. I am still only getting 10mpg. Any other ideas of what might be causing this?
Do you have access to an OBD-II reader? Any stored codes? What does it show for coolant temperature once fully warmed up?

Does the exhaust smell rich? Black soot in the tailpipe?
 
I am doing miles/gal
10mpg is super unrealistically low. Did you change your speedometer gear? Maybe jeep came with 215-75-15 tires originally and never changed speedometer gear? Even that wouldn't make a whole lot of sense because you are 30%+ off a normal figure