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i have the same problem, and i just welded my freakin exhaust manifold and ripped off the old holey exhaust and replaced it, i also have a 62mm TB and a k&n panel filter, what gives? i get like 14mpg on 31s and a 3" lift... i am gonna try an o2 sensor tomorrow maybe
I feeel your pain on the gas mileage. i have 3 road running XJ's an 86, 96, & a 2000. I've put the 96 aside for now to do some body work, and picked up driving the 2000 regularly. The 2000 is bone stock and it only gets about 250 mils per tank, yet the 96 only thing different is that I have 30's on it gets over 400 miles to a tank, and the 86 with the bored out 2.8 V6 gets about 380 miles per tank. So the older ones with many more miles are getting much better gas mileage than the new one. I'm told by my local Jeep dealership that the problem lies within the computer. If anyone has any info on that can you let me know. Because I would like to boost my mileage on the 2000 also.
I feeel your pain on the gas mileage. i have 3 road running XJ's an 86, 96, & a 2000. I've put the 96 aside for now to do some body work, and picked up driving the 2000 regularly. The 2000 is bone stock and it only gets about 250 mils per tank, yet the 96 only thing different is that I have 30's on it gets over 400 miles to a tank, and the 86 with the bored out 2.8 V6 gets about 380 miles per tank. So the older ones with many more miles are getting much better gas mileage than the new one. I'm told by my local Jeep dealership that the problem lies within the computer. If anyone has any info on that can you let me know. Because I would like to boost my mileage on the 2000 also.
i am with you guys too. i have a 2000 xj with a 3.5 lift and 31x10.5 mt's on it. i also have a light bar in the front between the grill with 4- 6 inches lights and a roof rack with 4 more and a a full size mt spare. i get like 11 mpg on the highway with the spare on the roof and maybe 14 if i take it off. i did just change my o2 sensor last night so we will see if it goes up. i also have a throttle body spacer and soon a k &n and hopefully an exhaust of some sort. i am driving back and forth between indiana and pittsburg pa. about 8 hours one way and i go through roughly 33 gallons to go one way. and then have to fill up as soon as i get either place. any help would be awsome thanks fellas. and for anyone that might be interested i am working on a round headlight conversion for it. i will get some pics on here as soon as i get some
My 01' consistenty gets 20-22 mpg (50/50 city-highway). Highest I ever got with it was 24.5 highway. +400 miles per tank easy. I use either Shell or Amoco/BP almost exclusively.
It is modded quite a bit. In addition, I've got Redline synthetic in all service points for the XJ. Keep it tuned well, reduced weight & drag, and keep the tires aired up correctly. In addition to your oversized tires being one issue, you may have carbon build-up in your CC. I would dose it with either Redline S-1 fuel system cleaner or MMO (marvel mystery oil). Both work very well @ decarbonizing. Increased mileage is one of the side effects.
Even in high modded form I've still exceeded the EPA estimate for the XJ which is 15/20 city-highway. :sunshine:
this might be a dumb question, but what does cc stand for? and what is your opinion on a better axle lube helping the fuel milage? like a synthetic or something like that?
this might be a dumb question, but what does cc stand for? and what is your opinion on a better axle lube helping the fuel milage? like a synthetic or something like that?
CC stands for "combustion chamber", this is the chamber right below where you put your spark plugs (can see it through the spark plug hole) into and where the fuel injectors spray atomized fuel into. This chamber can typically become fouled with carbon and using a good fuel system cleaner like Redline SI-1 or Marvel Mystery a couple few times a year or more is a good practice. For axle lube, I'm using Redline 75w-90NS front and rear and I've got nothing but praise for it. Quieter running is one aspect I noticed right away and as is with most full syn fluids this is usually due to less friction between moving parts. Redline in the crankcase (engine) and tranny and I must say my XJ is very quiet.
dude i did a 400 mile round rip the other day with 2.5 tanks of gas -_-
i feel your pain. I wish i had money for a new 02 sensor and since i have a rough ass idle im going to replace the map sensor too. hopefully gain a little back.
CC stands for "combustion chamber", this is the chamber right below where you put your spark plugs (can see it through the spark plug hole) into and where the fuel injectors spray atomized fuel into...
keep accurate; someone might be reading what you write.
spraying fuel into the combustion chamber is referred to as "direct fuel injection" and is a very new technology found on only a handfull of current engines. The Jeep 4.0 is not one of them.
I get about 260mpt with throttle body spacer, cold air intake, dynomax catback, m/t, and 31's, but my speedo says 55 when i'm going 60. It seems like i used to get right around 300mpt every time a few years ago and before the mods, but i've been slacking on the regular maintanance.
keep accurate; someone might be reading what you write.
spraying fuel into the combustion chamber is referred to as "direct fuel injection" and is a very new technology found on only a handfull of current engines. The Jeep 4.0 is not one of them.
ok, i should have know the cc thing, but oh well. i picked up some ams oil fuel injector and chamber cleaner at work the other day and put it in with a full tank tonight. the jeep is running bettter since the 02 sensor the other day and the power is back so i of course havent got my foot out of it yet. lol. we will see this week and when i go home to indiana next wednsday
xjs start slow, all of them. thats just how they are.
if by "a few seconds" you mean over 7 or 8, then maybe you need to look at the ignition, but i was told that a normal xj usually takes 4-6 seconds to start.
Geez... I've got a 1991, and just finished a 4.5" lift. My 1st post-lift tank got me a whole 270 MPT, down from 310 MPT. I've got the stock gear package, and have already started saving/making shop appointments for getting the 4.55's installed.
WHY 4.55 instead of 4.11? Because I was challenged by my RV dealer (we own a pop-up camper), and when he saw my new lift, he KNEW I'd be goiong to 33's when the 31's wear out... Oh yeah, he's an XJ owner TOO!
Right now, even with 31's, it's like driving uphill, all the time. I had a boner for a nice set of 4.11's, and was sold to buy, until I got queried about the whole pulling anything idea- I totally forgot about my damn trailer!
I'm told that if I went 4.11's, I could get immediate gas milage improvement, and I just met a guy from here in NH that just got the same thing- and his improvement went from 16 into the 21 MPG range. I played around with some of the calculators available here, and saw that I'll be LOSING MPG's when I switch to 4.55 while running the 31's, but I'll be able to pull anything I want too. Once I'm into a set of 33 sneakers, then I'll be back to "about average", whatever that is.
xjs start slow, all of them. thats just how they are.
if by "a few seconds" you mean over 7 or 8, then maybe you need to look at the ignition, but i was told that a normal xj usually takes 4-6 seconds to start.
Not true. Mine takes one to two seconds max. I rarely ever hear it crank. It starts like one of those push button luxury cars. maybe 4 seconds if it's below freezing out and the battery is weak. and this is on really old spark plugs and wires, and a fuel filter in the tank that has never been done. 125,000mi- I'll make a video If you want proof-
accurate; someone might be reading what you write.
