xjbuddy

hey all.
ok so my jeep isnt running as well fuel wise as when i first got it. i cant recall how much i was getting in mpg. but according to my overhead cluster its reading 11.6 MPG. i swapped out to neon injectors for my model year(98). and my muffler is non excistant. there is a straight pipe to the cat and connecting to the tailpipe. im due for my tune up and was wondering what plug i should go with? i heard allot of mixed answers. champion copper, champion platnum, autolights, NGK, NGK platnum. my jeep is a 98 auto. anything else i can do to raise my MPG's?. if i can gain atleast 1-3 mpg those are big numbers to me. not to mention gas is $3.61 a gallon and rising!!!

captainofiron

check your O2 sensors

also do a manual calculation for your mpgs, when you fill up do as recommended and only fill to the click every time, and zero out the odometer, then next time you fill up simply divide what your trip odometer says by the gallons of fuel you put in there

this will give you a rough mpg to compare to your computer.

aside from that you can also check your tire inflation
go with a lighter viscosity oil (i dont like to do this)
dont use ethanol fuels

ptonjeep

try a search there have been at least 4 different threads on this subjuect this year. search is your friend

TheKirbyMan

Driving habits make a huge difference. The lighter you press the gas pedal, the better your mileage will be (common knowledge, I know, but it's worth mentioning). Taking off quick from stop lights or stop signs and accelerating quickly when it's not necessary use more gas too (exception would be when you're merging in traffic or it's otherwise necessary for you to move quickly).

I don't know anything about the special spark plugs, but IMO I'd just run plain plugs and spend the money saved on tuning up the engine. Plug wires, cap, rotor, and make sure tires are aired up to the proper levels. Because what good will fancy spark plugs do if you spend your money on them but can't afford to get the rest of your ignition system up to par?

And I KNOW you won't want to hear this...but bigger tires are gonna affect your mileage. Your sig says you want to run 33s, that's gonna cost you since the bigger tires weigh more. I facepalmed once when I read a guy's post on another forum....he said he wanted 35s on his Jeep (with a 2.5L I4 no less)...then asked what kind of mileage to expect. lol

Gee oh Dee

Get a 4 cylinder car. You have a SUV, you can't do too much to help.

BeaglesXJ

Try a cold air intake and a new exhaust. Maybe new o2 sensors. Change your diff oil, engine oil, trans fluid and tcase fluid. I thought I read somewhere that a 99 and up intake would help a little too.

TheKirbyMan

Not to seem rude, but isn't paying for all those engine parts (intake, exhaust, etc.) or buying another car no different than just paying more for gas?

I do agree with changing fluids as he can though, if anything it'll prolong the life of the components.

Gee oh Dee

From what I understand CAIs are worthless on a XJ. Snorkel, however...
Depends on if you are looking at the long run.

Buying a fuel effecient car that you can re sell isn't a bad thing.

captainofiron

from the looks of it, the intake manifold runners are the choke point

Gee oh Dee

OK

wildbill1

This is a good point. I know a guy who took a trade-in beating on his full size van to buy a minivan that gets better mileage. I sat down with him and figured it all out. At $4.00/gal., he will start to get ahead when he has 275,000 miles on the minivan.

I work with a guy who has a fleet of vehicles. When gas spiked a few years ago, he went out and bought a Mini Cooper because it was good on gas. Now he's talking about buying an electric car. What does he drive 90% of the time? His Suburban...because it's comfortable.

fishtaconc

Agree 110% ^

xjbuddy

Thanks for the info so far I dont seem to have any DTC codes stored. But my guess is my O2 sensors are OEM. They had a good run i guess. In addition i now have my 33's installed and havent noticed any change at all. And theyre all at 34-35 psi. I am also considering the DUI kit. Maybe this will help a little?

TheKirbyMan

I still think that you'd be spending your money better if you work on the basics before considering upgrading parts. For example, I could spend money and buy a completely new MSD ignition system for my F150 -- new spark box, new distributor, wires, etc. -- and it can put out twice the voltage as my factory system, but if my carburetor is out of tune or the engine is otherwise in need of a tune-up, that new ignition system isn't going to benefit me much. I still believe that before considering upgrades, the basics should be taken care of first. You might be surprised at the difference.

vandelden21

I know this wont save your fuel but it deffinatly makes you keep tour foot outta it which will save fuel. Get a vacuum pressure Gage and install it try to keep as much vacuum up as possible. Place it where it'll stand out So you know when your foots in it.