My '99 equipped with the the Fitch F300 in line and 4 F5's in the tank has been giving me 24.5 avg between 55-65 mph, 23 if I run the A/C. Dont do much city driving, so cant even estimate there. I'm on 235/70-16 Yokohamas(touring tires)

 

XJ 98, 302k miles. All stock. 16 city, 21 hwy. Driving like an old dude, because I'm an old dude.

 

2000 Cherokee Sport
Auto
8.25/np231
3" lift
31" AT tires, canyon rims
142,000 miles

Some engine issues, exhaust needs replacing.

9-13 city
12-17 hwy

Lower end is with kayak, bike and some other gear loaded up. I never drive hard....too scared I'll make my engine issues worse.

 

Stock 90, 4.0, 267K. Stumbling around rich with the 703's in open loop 1/2 the time, (too much fuel for the ECU default pulse width), 13-14 Mpg. On the highway at temp in closed loop, a bit over 20. My coolant temp sensor resistance only goes down to to low 300's IIRC. I think is should be lower, which might bump it up a little from that 20. Idk.

Just to be clear, my 90 (renix), uses 18.6 lb/hr injectors. Works, and will pass smog, warm, but the 703's are a better match for the later Jeeps. I'm looking to go to 4 hole, 18# injectors, thinking my open loop mileage will improve. (running rich makes it take longer to warm up as well)

 

That is Ford Excursion with Jeep sticker! I cannot believe seller cheated you like that!

 

you are not old if you drive a Jeep!

 

My ' 86 Comanche (it's kinda like a Cherokee ) gets 14mpg when I'm on it and 16 mpg when I take it easy. That was with a MAF that was slowly going bad and running rich. That Jeep has a Chevy 350 (TBI motor with TPI fuel injection setup), 22 gal fuel cell, AX15, NP231, ~6" lift, Dana 60HP/Sterling 10.25, 4.10's, and 15/38.5 Ground Hawgs (among many other mods). Going to be replacing the MAF in the next couple days and hoping to get around 17-18 mpg with a kinda mixed city/country roads driving (don't really do any highway driving too often).

 

Hello all. 1st post.

98 sport. I6 auto. 30.5 all terrains. Completely stock otherwise-hopefully soon to change that.

I bought the Jeep last September, and have put just over 10k miles on her. I've done some mild wheeling here in SoCal (McCain Valley Road, Otay Mesa Truck Trail, Superstition) I used to have an 85 cj with the 4 banger back in the 80's-it would stall on steep inclines which was kinda scary. Thank Providence for Fuel Injection!

I've tried 87, 89, and 91 octanes. Shell, 76, and Chevron and have been tracking with Feul Log on my smart phone.

Best trip: 20.46 on a trip to LA. 76 gas, 87 octane.
Worst trip 11.24 wheeling cheapo gas 87 octane.

Otherwise it averages 15-16 mixed city and some freeway driving. I try to keep it below 70 unless road tripping-then i keep it below 75.

I've tried to ascertain whether octane matters. I've seen threads on here going both ways-but I honestly don't see a difference between 87 and 91-I've had good and bad on both.

It seems to like the top tier gas (especially Chevron) just because it seems to idle smoother, start quicker, and has maybe a tad more power. But I can't prove it.

The only way it gets better than 16 mpg is if I take it on a road trip and set the cruise.

I am going to try the neon injector swap when $ and schedule permits. Looking forward to the results.

Thanks to everyone who shares their knowledge. It's helped me greatly and I've just been lurking.

 

Im getting about 13-15.5 and i drive 90% highy on a full tank

Im also running a lift with 31s so i dont expect a lot

I expect to see and increase with the k&n airfilter assembly/ cleaned throttle body and mobil 1 full synthetic oil change

 

I appreciate that!

 

92 sport h.o. about 9 to 12...(i go wheeling everyday)

 

98 2 door 188000 4.0 automatic trans. lifted 1" 225/75 15 street tires.
With a mixture of highway and stuck in traffic I get 18.75 fairly consistantly.

 

90 laredo. 5" lift 33x12.5 mud terrains. I drive 50 miles a day on a fairly twisty hilly road (some long straights, some up and down small winding hills) I'm averaging about 15. I have an intake and exhaust. I'm going to make a combo of skid plates/wind diffusers (fairly light weight combo of steel and aluminium) and see if I can get her to glide better. When you start lifting a vehicle that's already dead as far as aerodynamics go, you completely kill the mileage. I'm going to try to get a little less wind resistance under the jeep... We will see what happens.

 

90 XJ, 3" lift, 31s... 18 mpg highway, 16 city....

 

99' 4.0 auto w/3.5'' lift and a magnaflow. just bought it and the 1st tank was 13.5 mpg it was mostly city driving and i was driving like a grandma. i just replaced the spark plugs with copper core, and i added sea foam. hopefully those help, ill post my next results
btw any suggestions for the air filter? keep it stock or replace?