94XjSport94

Ok I've talked with people with 97+ xj's and they say they get about 17 mpg city. My 94 gets 15 In town at best and i have a cold air intake and a throttle body spacer which helped. I know what all effects mpg and all that and I drive the jeep very gently I dont beat it. I just want to know is there anything different between the 96 down and 97 ups?

FiftySix56

Have you changed anything in your exhaust system? Exhaust plays a heavy part in your fuel economy; backpressure equals fuel economy at the cost of power. Aftermarket kits that increase horsepower screw you over on efficiency of fuel. One solution can be to put more bends into the system, or keep it stock. Another solution to your mpg issue could be putting in different injectors; specifically the ones out of a Neon. You can either pull them yourself, or there is a member of the forum that sells them for around $45.

EDIT: sorry lol i didnt read your post fully the biggest difference between your xj and the 97+ is the head and intake being ported differently. The newer head is ported for better flow, and the intake has smaller ports iirc. The only downfall to the newer ones is the turd that chryco calls the 0331 head.

tjwalker

Is tuneup hardware fresh? New Champion copper plugs gapped to .035, new plug wires, distributor cap, rotor and fuel filter.See where you're at after that.

Be sure to get at least THREE gas mileage samples before coming to any conclusions. And you must do the math. Miles driven divided by gallons consumed. Trying to extrapolate your mileage by the amount of miles per tank of gas is not that accurate.

BTW, if the oxygen sensor is old, consider replacing it. They have a finite lifespan of between 100k and 150k, depending on the efficiency of the engine. They can definitely have an affect on your mileage.

OOdynamite

I received a 2 MPG increase with my new exhaust kit...

FiftySix56

My bad, i shouldnt have said all of the kits screw you over, however i have seen a lot that do.

94XjSport94

Ive got brand new distributor cap button wires and plugs so that shouldnt be a problem. ive been getting around 14 15 or so in the city so anymore would be great but the money is tight

sojimomo

The 97+ have a hotter cam and better intake. I put a 97 block in my 92 and i get great mpg I will do the same with my 88 when i get the money.

CoffeeCommando

Actually the 91-95 heads have the largest ports. I have a 98, and after finding out that Titan had a 91-95 head on there I did research and found that they were the best head units for horsepower due to increased port size. I'm not sure where 97 and 98 heads stand, but in 99 or 2000 they started making the ports smaller, and are therefore not recommended for strokers if you are seeking to maximize power.

tiwvr1

If you did a tune up already, make sure air pressure is good, all fluids are new and clean, snythetic motor oil helps a tad, Seafoam it, Replace FRONT 02 sensor. Experiment a bit, sometimes older motors get carbon build up, running a higher octane gas can have a HUGE improvment on milage. My 94 zj with v8 will get almost 50 more mpg with 89, Same thing with my 01 jetta. BUT not ALL motors will benifit from higher octane, u just have to try and see.

94XjSport94

I haven't replaced the o2 sensor but everything should be great all fluids are relatively new except the radiator that needs a flush. Whats the deal with sea foam I've heard of it just never used it or anything.

tiwvr1

Seach here to see how to do sea foam. If your motor has a lot of carbon build up on the pistons, it can create hot spots, and valves to stick a tad. A hot spot will cause detonation going up hills. Sea foam helps to get rid of this carbon by breaking it up.

94XjSport94

Yeah that's kind of what I knew about it but I just didnt know how to do anything with it other than mixing it with your gas but I'll try that here soon

cdawall

i get better than that with 33s and stock gears on my 1994. mines got a newer o2 sensor, fresh belt, newer air filter thats about it. original plugs, wires and cap.