Gas mileage improvements?

[Talyn]

Take out the spare tire and jack (have AAA road service or someone to bring you these when needed).

Great idea. In the time you are waiting for AAA you could have changed the tire and been on your way already and not be standing around looking like an asshat that can't change his own tire. And that 60 or so pounds isn't going to make that much difference anyhow. Especially at highway speeds.

 

[kastein]

Great idea. In the time you are waiting for AAA you could have changed the tire and been on your way already and not be standing around looking like an asshat that can't change his own tire. And that 60 or so pounds isn't going to make that much difference anyhow. Especially at highway speeds.

X2.

Best gas mileage so far: 23.13mpg. 91 MJ, 1500lbs of cargo. 4.0/aw4/d35, 3.55 gears, p225 tires. 55-65mph on the highway. Engine and tranny are tired at 220+ thousand miles, no rebuilds. Air filter was oil soaked.
Average in the same vehicle, EMPTY, driving like a bat out of hell: 16mpg.

 

[kidarkitect]

wrenched, hows your mileage doing? any improvement?

 

[CharlesS]

UPDATE:

Replaced the factory original fuel injectors today with ones that I purchase from Precision Auto Injectors.

http://www.precisionautoinjectors.com

The old ones had 115K miles on them and while they weren't leaking externally they were definitely showing signs of leakby after the Jeep was shut off...
After running the engine for 15 minutes; the indications are smoother idle and better throttle response.
Went for a drive in the local mountains and the Jeep has more power in the hills and requires less throttle to pass slower vehicles.
Filled up and drove 35 miles thru the hills and the gas needle was still above F when I arrived home. Previously the gas needle would be below F even if I was driving on the highway.
Not sure how much the gas mileage has increased, but over the next several days I will know more.....

 

[Bdiddy11]

Fill gas up half tank at a time

What does that do? Is there some kind of trickeration to filling up half tank at a time? I've heard of filling up in the morning is better because the gas is more condensed or whatever from being colder and you get a little more bang for your buck.

And not to fill up if there's a gas tanker there filling the station up because it's stirring up the gas and getting the bottom sediments riled up...

 

[cwstnsko]

I think he was suggesting running 1/2 tank or less to save the weight of the gas

 

[XJEEPER]

UPDATE:

Replaced the factory original fuel injectors today with ones that I purchase from Precision Auto Injectors.

http://www.precisionautoinjectors.com

The old ones had 115K miles on them and while they weren't leaking externally they were definitely showing signs of leakby after the Jeep was shut off...
After running the engine for 15 minutes; the indications are smoother idle and better throttle response.
Went for a drive in the local mountains and the Jeep has more power in the hills and requires less throttle to pass slower vehicles.
Filled up and drove 35 miles thru the hills and the gas needle was still above F when I arrived home. Previously the gas needle would be below F even if I was driving on the highway.
Not sure how much the gas mileage has increased, but over the next several days I will know more.....

Charles,
Keep us updated on some actual stats on improvement. I'm at 165K miles on my 2000 and ave. 60 miles per day freeway/city.....I'd like be be getting better that 15mpg.

 

[srmitchell]

Charles,
Keep us updated on some actual stats on improvement. I'm at 165K miles on my 2000 and ave. 60 miles per day freeway/city.....I'd like be be getting better that 15mpg.

Im running a similar rpm to you on the freeway. (Im at 4.56 and 32's)

Just switched to those precision injectors 2 months ago.

2 recent trips
-60 miles round trip to Fortuna CA, used about 1/8 of a tank.
-80 miles round trip up to the local snow spot- Lots of huge hill climbs, and A LOT of high rpm wheel spin in the snow, with 4 people in the jeep, used a 1/4 tank.

Gas mileage is much better.

 

[CherBear]

Im running a similar rpm to you on the freeway. (Im at 4.56 and 32's)

Just switched to those precision injectors 2 months ago.

2 recent trips
-60 miles round trip to Fortuna CA, used about 1/8 of a tank.
-80 miles round trip up to the local snow spot- Lots of huge hill climbs, and A LOT of high rpm wheel spin in the snow, with 4 people in the jeep, used a 1/4 tank.

Gas mileage is much better.

Dont forget that the XJ fuel gauge isnt linear. So the first half of your tank isnt the same volume as the last half...

What I am saying is that it is hard to compare numbers if you just eyeball the guage.

 

[kastein]

yeah... "half tank" and similar terms are worth the pixels they are displayed on. Real full-to-full measurements are the ONLY reliable source of info on fuel consumption.

 

[srmitchell]

True, but a similar trip before seemed use much more.

 

[DieselSJ]

True, but a similar trip before seemed use much more.

"Seemed" being the key word here. That is about as accurate as a butt dyno. Until you have actual miles/gallons used data you have no definitive proof of anything. A 5 tank average of before and after would be good.

 

[CherBear]

"Seemed" being the key word here. That is about as accurate as a butt dyno. Until you have actual miles/gallons used data you have no definitive proof of anything. A 5 tank average of before and after would be good.

Agreed, the differences we are looking for (~1mpg) are impossible to "feel". Give us raw data.

 

[oldmantompkins]

So I have a stock 01 that I recently bought with 95k. Replaced plugs and changed nearly all the fluids. Ran both sea foam and fuel system cleaners a couple of times and im averaging 19mpg combination city and highway. I have had people tell me they get 20-21 mpg in their cherokee, I dont know if I should believe them.

It did not get 19mpg when I bought it. Sea foam fixed its rough idle and the fuel system cleaners brought some of the mpg back. Im happy with 19 but I guess its fair to say I wont stop trying to get better mpg.

I know there is a lot of controversy over the additives and whatnot but the sea foam and the gumout fuel system cleaner did make a difference.

Im measuring my mpg using exact amount of fuel added from the gas light so I believe my measurements are accurate.

 

[cwstnsko]

People saying they're getting 20-21 are generally running with the 5 spd manual transmission.

I dream about seeing 19 mpg someday in my 98 with AW4. I have been averaging about 13-14 lately with 3" of lift and 31x10.50s, stock 3.55 gears, GPS verified corrected speedo. I have a set of Precision Injectors and a new set of Champion plugs sitting on the counter at home waiting to go in. My pre-cat O2 sensor is less that a year old. The last time I checked, my manifold was not cracked. The thermostat is a new OEM part and the Jeep runs beautifully

 

[CherBear]

I can get 20+ mpg highway. Stock suspension and 235s, aw4. Intake, exhaust.

Lay off the skinny pedal!!!

 

[kastein]

I can get 20+ mpg highway. Stock suspension and 235s, aw4. Intake, exhaust.

Lay off the skinny pedal!!!

likewise, in multiple jeeps.

Hell, I computed my mileage for my last tank of gas in the 98 (stock everything, new upstream O2 sensor, AW4), which included a trip out to NY on the mass pike for the hell of it, hitting 115mph at times... and I got nearly 16mpg. I get 18, 19 all the time in it when I'm commuting. I don't know how the hell people make their mileage so terrible. Heck, I get almost 10mpg dragging a 2500lb trailer at 80mph with an AW4, stock 3.55s, and 33 inch tires, and I've heard people say they get worse than that with no trailer, not driving it like they stole it.

 

[DieselSJ]

People saying they're getting 20-21 are generally running with the 5 spd manual transmission.

I dream about seeing 19 mpg someday in my 98 with AW4. I have been averaging about 13-14 lately with 3" of lift and 31x10.50s, stock 3.55 gears, GPS verified corrected speedo. I have a set of Precision Injectors and a new set of Champion plugs sitting on the counter at home waiting to go in. My pre-cat O2 sensor is less that a year old. The last time I checked, my manifold was not cracked. The thermostat is a new OEM part and the Jeep runs beautifully

My old '88 got 19-21 with 3" lift, 31's, and 4.10s and a AW4. Your problem is the gears + tires - you are lugging the engine too much. You need to let it spin up more so that it can work easier.

 

[Voteban]

Earlier in the thread somebody said you have to change the oil after you fun sea-foam through. Should I run my sea-foam through before I change my oil? It's in need of an oil change soon... So is it better to wait?

That is worded horribly but I think it gets my point across. :gee:

 

[Dr. Dyno]

I just completed a 336 mile (541km) road trip this weekend. Average speed was 60-65mph and most of it was in 5th gear. I filled the fuel tank to the brim and zeroed the trip meter before I set off. After I returned I refilled the tank and it took 15.9 US gallons (60.2 liters) yielding an average of 21mpg or 11.1L/100km. I was pretty impressed.
I normally get 16mpg (~14.5L/100km) city and 19mpg (~12.5L/100km) highway (75-80mph cruise).
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1992 XJ Laredo - AX15 5-speed - 4.6 Stroker
14.63 @ 94.4 - 201.7rwhp, 258.2rwtq - 3450lb no driver