is there anything basic that i can do to raise gas mileage in my xj

(besides going easy on the petal and going the speed limit haha)

 

Don't lift it and put big tires on it.

 

well yeah... thats obvious... but im talking about little upgrades here and there can improve it

 

What are you getting for mileage now?

 

Injectors, keeping up with maintence (tune ups ect), better air filter may help

 

upgrading to an aftermarket exhaust and a less restrictive air filter will give you a little mpg gain... that is if you can keep your foot out of it after being tempted by the HP and torque gains.

narrower tires will also reduce rolling resistance and theoretically give you an improvement, but I've never really benefited from such a thing... however, the more aggressive your tread pattern is, the worse your gas mileage you will get...

a road tire will give you the best, but your off-roadability will suffer..obviously a mud tire will allow you to do great off-road, but your mpg's will suck... so a mild AT tread will allow you a decent off-road performance without killing your mpgs.

on that note, make sure you are inflating your tires to the correct pressure that is on the door - not the max inflation pressure that is on the tire itsself

 

Exhaust, tire choice & pressure, making sure the engine is operating properly...that's about it with an XJ.
They are a brick on wheels driven by a rather agricultural motor though a lossy automatic trans, with a front drivetrain that's always spinning.
The manual trans seems to do notably better...but that isn't an easy swap if you have an auto.
Perhaps waiting for the floorpans to rot away then powering it Flintstone-style might pick up a few MPG.

 

Maintenance, maintenance MAINTENANCE!!!

Everything from oil changes to keeing the front end tight will help maintain MPGS. Anything you can do to make that engine work less improves economy.

And despite the fact you said you know I want to reiterate that driving habits make or break fuel economy. No mattter how slick your XJ runs if you drivie it like you stole it you will drink gas.


Get crap OFF the roof! Yeah, we all love roof racks and lights but they jack up fuel mileage.

 

No.
if I buy a completely different tire than the vehicle came with, which recommends a different psi, then the note on the door is 100% irrelevant.

Take low profile tires as an example. Because of the shorter sidewall, they recommend a considerably higher psi than regular tires.

 

My manual xj seems to do damn well. I'm avg 15–16 mpg with stock gears an exo cage and 5 inch lift on 33s

 

Its got 200k on it too, but I keep up on matinece and I've got a good cone air filter and a real nice thrush exhaust.

 

The best improvement I made, was to pick up a 4 banger beater. That I use most of the time for a work vehicle. The XJ, I use for a dog hauler, hunting, fishing, camping, and winter. It save me about $1800-$2000 in gas a year, just driving to work.

 

This is the big question^^^
You may be getting the max out of her now? We can't tell unless you post what kind of mile you are getting now!

 

Right you are, however from what he says, it sounds like he's staying with nearly stock size tires so the inflation pressure on the door will work fine unless he goes with a higher load index... Large tires and low profile tires, of course throw this right out the window... But at that point you STILL don't go with what is on the sidewall... You have to use the chalk line across the tire method to determine your appropriate contact patch.

Again, for HIS instance... The pressure on the door is the most correct.

 

I've heard that ensuring you have a fuel cap that effectively seals can make a difference. They say that non-sealing caps allow for fuel evaporation. I bought a new one and saw my MPG go from 13 to 15. That's not scientific; I've only refilled once since the change. So I'll keep monitoring before I can comfortably attribute it to the gas cap.