I was getting about 11 until I saw this... Very interested to see what I get now.

 

Just replaced my air filter a couple days ago. The old one had some dried mud on it .
I wanna see what I get too, my guess is the mileage will probably stay at 12.

 

Im pretty sure you can stay in 4x4 everywhere you go if you want to without any problems. My owners manual says not to be in part time 4 wheel on dry pavement, but nothing about being in full time 4wd.

 

Full time 4WD is really another name for AWD. He's fine driving anywhere with it on. Part time 4WD needs to have a slippery surface to operate on, otherwise you get driveline binding and other bad stuff lol

 

We have C-9 in Indy, it's just like that. I got to do all that cool stuff without leaving the school. I think everyone should have to take auto shop. We can't all be computer techs! I owe a lot to my shop teachers, at the very least the thousands I have saved on car repairs.

 

This def should be good.

You guys must really be pounding on ur xj's. i baby the hell out of mine and i just got a best of 3 @ 19.7 mpgs. The second week i got 20.3mpg. I just did a tune-up this weekend so i'll do another best of 3. I don't shift above 2grand and i don't run her over 65 on the highway.

I Also have a mudfrog exhaust and high flow cat sitting in my spare room waiting for some decent weather to put it on.

 

I baby both of my XJs and I keep my AW4's shift points as low as possible (usually around 2100 RPM)

I have heard that the 1999 XJ 4.0L's got the best gas mileage out of all the years the 4.0L HO was produced in the XJs, which is probably why you're pulling better fuel economy than we do. Not to mention, most of our XJs are modded and have lifts and larger tires

I definitely gotta go get some new spark plugs for my Jeep and see if that'll get me above 12mpg.

As for your exhaust setup, be prepared to LOSE some fuel economy. XJs are weird and they dump more fuel into the intake if the backpressure is reduced. I'd watch out because I lost 1 mpg after I put my flowmaster on.

 

Agreed, Automotive Technology should be a graduation requirement just like health class and all that other B.S.

If we all knew how cars worked the world would be a better place

I owe about $23.79 to my shop teachers for coolant right now LMAO, and I also owe them tons of respect for all that they have taught me in class. I definitely would know as much as what I know now without them!

 

I'm still at stock height for now but i am on 235's duratracs. I did not know about 99's getting good milage.

I hope you are wrong about the exhaust thing. i guess i'll find out.
I've been are performance cars aloooooooong time and never heard of mpgs getting worse when you get rid of some back pressure. thats just weird.but we'll see and i will post up numbers when i put it on.

 

235 is the right size for stock as long as your XJ isn't the base model, then it is the 215.


Yeah, I thought my shop teacher was BSing me when he said my flowmaster would bring the mileage down. He said all inline six engines love a good amount of backpressure. Let me know if you get better mileage.

 

Ok. I will.
Stock size tires for my 99 was 225 not 235. just an fyi.

 

I'm almost certain xjs only got 225's and 215's. As far as I know, they never came with 235's , in any package


Edit, I'm not getting involved in this exhaust arguement again

 

Every stock XJ i've ever seen had either the 215s or 235s. My Laredo came stock with 235s, my friend's 99 Sport has stock 235s, and tons of XJ's i've seen in parking lots were running 235s. I've never seen one on the 225s which is weird.

 

Mine came with 225's and thats what the build sheet said it came with stock

 

My 93 was a police package and still had the window sticker. The upgraded tire package was 225's

Id love to see a build sheet with 235's on it