What mpg is everyone getting w/an auto xj?

[Super mud]

I wonder if high density cold air makes a difference. He was in Canada I think? Or could the computers for Canadian jeeps run the engine leaner than Californika-EPA programs here?

haven't read the entire thread but does anybody modify the Map sensor voltage to run leaner?

 

[volaredon]

97 XJ 4.0 AW4 3.55s no lift but LT 235/15 Michelin "hiway" tread; usually about 17 MPG (usually a lil less w/ winter gas but with freshly rebuilt/cleaned'tested injectors its gettin that even with winter gas) straight hwy run doing about 70, and MPG is 20-1/2

97 TJ 4.0 STICK 3.07s also runnin 235 Michelins (A/T tread) around 14-14 1/2 with this $#!tty winter gas; about 25K since those injectors got "the treatment";
I never actually "checked" MPG on that trip, but miles per tank went WAY up when my son and me drove it loaded to the gills w/tools and camping gear across I 70 to Vegas and back, running mostly Sinclair gas once we left Illinois

all I know, is that 3.07s SUCK A$$ 5th gear is all but useless; was more so when I had 31s on there. in same-style driving both my XJs with 3.55s and A/Ts have run circles around this one MPG wise. I do have a set of 3.73s for the rear but I need a different carrier to put them in + the matching guts for the front before I can swap; I have a feeling econ will go up after I swap gears.

but even so both my jeeps are still more economical to drive than my 2WD 94 Dakota reg cab shortbed with its 3.9 A/T and 3.55s..... I have been experimenting heavily with that truck to increase MPG; it may well get the 318 and the 5 speed that my kid's friends have layin in their barn.. (their daughter rolled their Dakota while playing w/ the radio)
I drive the farthest but thanks to the wife and kid, I get the gas pig;
unless the snow and salt disappears and the kid gets his Ramcharger out that is.... all stock TBI 360 gas hog and gutless..... I wish I had teh $ to build that 360 MY way....truck has never seen snow; bringing that home was the reason that we went to Vegas......

 

[muddypunk]

Mine is a 88 renex power everything and 225-70-15 3.55 AW-4 180,945 for miles and I get about 17 average and just under 24 (23.788) is what the math puts out . Its had a fresh tune-up and gets Mid grade 89 oct and runs smooth also my 95 AX-15 4.5 lift and 32's with 3.73 gets right about 16 and 21 on the freeway Im happy with that I guess I could always get a full size rig and not get as far off road.

 

[djlarroc]

well, just got back from a 435 mile camping trip w/about 10 miles of 4x4 use. Loaded w/gear, and very windy. Used about 20 gallons = 21.75

 

[Customizer1000]

Between 13 & 15

 

[RenegadeStang]

'98 4.0L/AW4, 3.55's, 225/75 BFG Long Trail Tour, creeping up on 200K miles = 15-16mpg city

 

[Devilfrog]

'00 4.0L AW4 3.55 with '93 head and exhaust.

Average 24-ish highway, been as high as 26, low as 18 ... All depends on how much lead in my feet. These are all based off 500 - 1000km round trips to work.

But that was all stock ... Got a feeling that's about to change.

 

[beastlydumass]

95 aw4 3.55 4x4 siting on bald 265/75/16 old mtr with 2" budget. geting 12 city and 14 hwy. in florida. got a 2wd 95 aw4 3.55 on 3" with new 235/75/15 wrangler radial. geting the same. both 4.0

 

[O-Gauge Steamer]

98, AW4, P285/75R16, 4.56:1, Supercharged.

17+ in town, 20+ Highway.

IMO, it is the overall gearing that makes the biggest difference. With the tire/gear combination I run, the Heep is geared 10.9% shorter than stock which results in slightly (yah, 11%) higher RPM for any given road speed.

Helps a lifted Heep. A goodly amount...

Now then. For those wonderig just how in the world I can be precise in the measurement.

A negative 10.9% was what I had to put into my AEM F/IC in order to get the speedometer/odometer corrected. Currently, the error in both is less than 1%.

 

[Antiferret]

i have a 96, auto 4.0 HO - 31's 3.55's

i used to get get 12 Litres per 100 highway, 19-25litres around town.

put in some Holden commodore injectors (engine based on your Buick 3.8 v6) and have dropped to 10L/100km highway and 16-18 town.

even though they flow less fuel, they support higher hp, more holes helps the atomization.

i have regained my low rpm punchiness. its like stock accelleration even with the 31's!

 

[weebur]

'97, 4.0L, auto, 4WD, 3.55:1 gears, tuned, 235/75R15 AT @33psi, 87 octane, Spector air filter. Long term computer average (combo city/highway) with odometer error correction for larger tires= 13.8 mpg.

 

[weebur]

Sorry for the double post but edit time expired.

'97, 4.0L, 133K, auto, 4WD, 3.55:1 gears w/locker in rear, tuned (NGK V-Power plugs good quality 8mm wires, clean TB, new IAC and TPS), 235/75R15 AT @33psi, stock suspension, 87 octane, Spectre air filter, full synthetic oil everywhere, stock exhaust, original upstream/downstream O2 sensors. Long term computer average (combo city/highway mostly city and driving like an old man that I am) with odometer error correction for taller tires= 13.8 mpg.

Thinking about:
Replacing upstream O2 sensor
Replacing stock w/4-hole injectors
Replacing plugs with Champion copper

I'd do a lot of work and spend some cash if I could even get close to some of these 20+ mpg claims.

 

[MAY POP]

98 4.0L 183K 3.55 gears. 225/75-15 Firestones at 35 psi.
47 miles each way to work and back 94 total daily. Some time spent sitting in traffic.
18-19 average. Could stay at 20 if no sitting in traffic.
This is staying with traffic speeds up to 75 MPH.
Ron