My Gas Mileage Thread

[Mudderoy]

I've been collecting date, distance (as measured by trip odometer), and gallons needed to fill the tank since July of 2008.

Here is my 2008 data.
http://xjtalk.com/images/special/jeepgasmileage2008.jpg

I was actively working on gas mileage improvements and you can see the trend line shows an increase in gas mileage.

Here is my 2009 data. I just got my highest gas mileage since I've been collecting the data. 13.75 mpg
http://xjtalk.com/images/special/jeepgasmileage2009.jpg

Most recently (last several months) I have been working on improving the engine coolant temps. You can see that the trend line show a general decrease in gas mileage. This may be me just not giving a **** and driving the way I like to. Fast starts, fast stops. Heavy on the petal. :D

[muddeprived]

Man you keep track of data pretty well. I don't know my mpg, all I know is I never get 200 miles per tank. :smiley-laughing021:

[Mudderoy]

Man you keep track of data pretty well. I don't know my mpg, all I know is I never get 200 miles per tank. :smiley-laughing021:

I have a PDA in my Jeep that I use for music, gps, e-mail, etc... I just record the gas mileage information in the "Notes" each time I fill up.

202 to 210 is what I get, so now you know your gas mileage. :thumbsup:

[Melissa]

Thats to high tech for me, I just check my mpg at every fill up, I'm getting 24mph

[Logans91XJ]

I honestly don't care and don't wanna know... :o

Its paid for and doesn't really cost me a whole lot.... Insurance is cheap and my bike is my main transportation and that get on average 40mpg and is pushing 104RWHP!!

[AJ99]

trip mileage??? WTF is that my mileage never changes its been stuck at 168XXX for a year... oh ya thats because my spedo doesnt work (not hooked up) LMAO... my MPH gauge is my gps

[COSXJFAN]

I get about 40 mpg in town...














in the pimp wagon, A.K.A., the Geo Metro. Closer to 50 on the hwy, but I go nowhere fast!! LOL!!

[pvt.Tadpol xj]

I get about 40 mpg in town...

I am not sure what im getting on MPG. I do know that last year I drove to dallas and back for me thats about 120 mi round trip burned about a 1/4 tank. and this year I have been making all kinds of improvements under the hood, and some small modifications, I bet the MPG is not bad, not bad at all.
I am in planning now to get some more of that heat out from under that hood before summer comes back, and I am still thinking on my cooling system.

[pvt.Tadpol xj]

Hey you are getting 24 MPH! or did you mean 24 MPG

[Mudderoy]

Well my gas mileage data collection has completed for the year, 2009.

http://xjtalk.com/images/special/jeepgasmileage2009.jpg

During this year I added a;

Custom winch bumper. (100 lbs)
- I removed the front factory skid and the factory front bumper.
Bushwacker fender flares
4 KC lights on the winch bumper (drag)
Superwinch (100+ lbs)

I saw a steady increase in gas mileage in 2008 and in 2009 there has been a slight decline. I know one reason for the 2009 decline is my right foot. 2008 I was very concerned about the price of gas so I was talking it easy on the skinny pedal. :driving:

[xjjeepthing]

I don't check mine. I don't want to know

[Mudderoy]

I don't check mine. I don't want to know

I get about 205 to 225 miles per tank. I have the 18 gallon tank.

I'm glad I kept up with it. I just wish I had before I started noticing the poor gas mileage.

Also I'm going to try to improve the gas mileage. Injectors and OEM O2 sensors. With this information I'll know if they make a difference.

[firehawk]

If I stay at 65mph or under I can get right at 20 mpg. Around town I get about 15 mpg.

I'm old, so I rarely drive over 60 anyway. But I DO turn off my turn signals though!:thumbsup:

[Mudderoy]

If I stay at 65mph or under I can get right at 20 mpg. Around town I get about 15 mpg.

I'm old, so I rarely drive over 60 anyway. But I DO turn off my turn signals though!:thumbsup:

I need to get my scanner on a 1998-ish XJ here around town. I suspect my O2 sensors are running a little high on the voltage. I just want to make sure that the voltage really is high before I throw more parts at the MPG problem.

[XJ Rat]

I need to get my scanner on a 1998-ish XJ here around town. I suspect my O2 sensors are running a little high on the voltage. I just want to make sure that the voltage really is high before I throw more parts at the MPG problem.

I've got a 1998. About 10 miles away from the Katy freeway at the Grand Parkway & Mason Road.

What exactly are you scanning? Educate me.

[Melissa]

I just got back from McMinville tuesday ( 5 hours one way ), while I forgot to check my mileage comming back, going there fighting the wind, I only got 16.5mpg, with my cruise set on 66 :eek::eek:.............Not Good!!!

[4.3LXJ]

That wind in the gorge can be nasty Melissa. I had an Impreza with four people and a bicycle on top that wouldn't buck the wind in 4th gear. Going east, just put a sail up.

[Mudderoy]

I've got a 1998. About 10 miles away from the Katy freeway at the Grand Parkway & Mason Road.

What exactly are you scanning? Educate me.

I have a blue tooth OBD II scanner. It connects up to the jack just under the dash on the left had side. I use a laptop with software that connects to the scanner and records data from the various sensors.

So no damage, splicing etc... to your Jeep just plug in, drive around, record data, disconnect and done.

[4.3LXJ]

Also I'm going to try to improve the gas mileage. Injectors and OEM O2 sensors. With this information I'll know if they make a difference.

Mud, one of the things most people ignore is the O2 sensor. They should be changed regularly. When they age, they may still function, but cause a rich mixture which of course translates into poor milage.

[Mudderoy]

Mud, one of the things most people ignore is the O2 sensor. They should be changed regularly. When they age, they may still function, but cause a rich mixture which of course translates into poor milage.

Thanks, but those were changed before I went to the 4.56 gears. Nothing I have done has made any major improvement on the gas mileage.

That's one of the reasons why I'd like to record some data from another XJ same year. See if my readings are really rich.

[Melissa]

That wind in the gorge can be nasty Melissa. I had an Impreza with four people and a bicycle on top that wouldn't buck the wind in 4th gear. Going east, just put a sail up.

This is true......... expecially at The Dalles, the wind was trying to knock me into the center divider, maybe next round, I'll stop and buy a sail from one of the wind surfers :rotfl2:

[BlueXJ]

Wind and XJs don't do well together. It's a box on wheels and aerodynamics were never even thought about by AMC or Jeep when designing it.

[TheWeiss]

So how often should the O2 sensor be changed? My XJ is at 183K and I've never changed it (unless the previous owner did 90K ago).... I'm guessing I'm a little overdue?

[Mudderoy]

So how often should the O2 sensor be changed? My XJ is at 183K and I've never changed it (unless the previous owner did 90K ago).... I'm guessing I'm a little overdue?

Honestly, if the gas mileage is good, I wouldn't touch it until I needed to.

[TheWeiss]

I'm getting 14-16 with mixed driving riding on 30's. I haven't seen over 18 MPG's since I added some coil spacers, slightly higher leaf springs and 30 inch tires. I'm thinking something has got to be off when I see the mileage you guys are getting with actual lifts.

[4.3LXJ]

So how often should the O2 sensor be changed? My XJ is at 183K and I've never changed it (unless the previous owner did 90K ago).... I'm guessing I'm a little overdue?

I have heard some recommendations from manuals say they should be changed every time the engine is tuned up. But I think every 100,000 is good. There many on other forums that have XJs that have never had theirs changed and wonder why they have poor gas milage. No codes or anything. They change it and get 4 or 5 mpg back.

[Mudderoy]

I have heard some recommendations from manuals say they should be changed every time the engine is tuned up. But I think every 100,000 is good. There many on other forums that have XJs that have never had theirs changed and wonder why they have poor gas milage. No codes or anything. They change it and get 4 or 5 mpg back.

That didn't happen to me and now I am wondering if it because I didn't use OEM O2 sensors.

[4.3LXJ]

I always use Bosch

[Mudderoy]

I always use Bosch

That's what I used, but I heard someone (or read it somewhere) that they may be too short (in the exhaust pipe).

[4.3LXJ]

That's what I used, but I heard someone (or read it somewhere) that they may be too short (in the exhaust pipe).

All I can say is that when I had my pipe sniffed it was pronounced "very clean" on hydrocarbons. That was in a 2 1/2" pipe. I haven't had it sniffed on the 3" yet though, but it runs real smooth so I don't think that is a problem.

[Mudderoy]

All I can say is that when I had my pipe sniffed it was pronounced "very clean" on hydrocarbons. That was in a 2 1/2" pipe. I haven't had it sniffed on the 3" yet though, but it runs real smooth so I don't think that is a problem.

This may be a repeat...

Now I have a check engine light coming on, it goes off after a couple of days, stays off and comes back on.

The 4 times I have checked, and cleared it, it was P0305(?) cylinder #5 misfire.

So either I have a new problem or this is related to my MPG issue. The gas mileage has NOT changed since the check engine light has started coming on, perhaps about 8 months ago.

With the upstream O2 sensor reading rich and now a cylinder misfire on #5 I am starting to suspect the #5 injector. Even though the cap, rotor, plugs are less than 6 months old, the plug wires may be a couple of years old. So those would be the more likely candidates. I need to move the plug wire from 5 to another cylinder and see if the mis-fire moves. If not then I'll need to change the cap and rotor and plugs.

If it still doesn't go away and the #5 plug is clean (or at least looks like the other 5 plugs) I'll replace the injectors.

Anybody see anything wrong with that? Missing something?

[4.3LXJ]

Nope. that is a nice methodical way to approach it. I do have a suggestion though about your misfire. You have had overheating issues, which indicates hot under hood temps. Muddeprived did some work on this, so you might PM him. But he added hood vents and insulated his injectors and lines and has not had the misfire since. It seems to be related to heat saturation of the gas in the line and injector causing gas evaporation. Those injectors need liquid to fire properly. Also, on a side note, cool gas is like cool air. Produces more energy when burned, thus increasing horsepower and milage.

[Mudderoy]

Well after having a very low 10.78 mpg on 1/5 I was a little concerned. The 27th was the trip to Spring Creek, and I burned a LOT of gas that week!

Anyway the next fill up (1/10) showed a mpg of 11.24 then (1/18) a mpg of 13.6. Today I filled up and calculated a mpg of 13.3. I got 233 miles on 17.624 gallons of gas.

The things I have read and experienced about a 4.0L Jeep engine is it really doesn't matter much how you drive them, they'll get about the same gas mileage. Sure you can drive 100 mph and watch the needle drop, but driving easy doesn't make a big difference in your miles per gallon.

The thing that was troubling me was how erratic my mpg graph was. I would expect to see a pretty level graph between 13.2 and 13.8 mpg (at least in my case).

That wasn't what I was seeing. I could drop to the mid 10's or go as high as the upper 13's. I thought this was pretty strange, so I tried to think why I keep seeing this pattern through out each month.

Then it hit me. Primarily because of the Spring Creek trip. 4x4 vs 2x4. Now don't laugh. I know several people have stated that you use more gas in 4x4 than in 2x4. In my defense I read in the owner's manual that the gas mileage was the same for 2x4 and 4x4 operation.

In the 1998 models all the parts are moving, so running in 2x4 has all the same parts in play as the 4x4.

I've been trying to keep it out of 4x4 (NP242 so I can run 2x4 anytime). I think this is why my last two mgs have been 13.6 and 13.3 mpg. That is the level of stability I would expect to see.

This may be why people with lifted XJs are reporting 16, 17, 18 mpg. Perhaps they have a NP231 and they seldom use 4x4.

[4.3LXJ]

That is true. Full time 4X4 uses more gas because of more parts turning, but the biggest reason is the energy absorbed by the fluid coupling. If you had hubs or a disconnect you would get even better milage.

[Mudderoy]

That is true. Full time 4X4 uses more gas because of more parts turning, but the biggest reason is the energy absorbed by the fluid coupling. If you had hubs or a disconnect you would get even better milage.

But in a late model XJ all the parts turn either in 2x4 or 4x4, right? The only difference is in 4x4 power is being applied to the front and back axles. So I can't understand why the gas mileage would go down unless I am having to apply MORE power to achieve the same acceleration.

I mean the same parts are moving the same fluid is being compressed, moved, etc...

What am I missing?

Also I have read (and anyone can write anything true or not) that lockable hubs make no difference in gas miles. .5 to .25 mpg is what I remember. Hardly worth the $1500(?).

[4.3LXJ]

Friction in the fluid coupling and gears.

[Mudderoy]

Friction in the fluid coupling and gears.

I need to develop a technology that eliminates friction and taxes!

[4.3LXJ]

Death and taxes are a given, unless you are a US Congressman then you can eliminate taxes:eek:

When we got fancier with our 4X4s we paid a price in milage. Full time costs about 3 mpg. No hubs about 1.5 - 2 Mpg. I don't know what we gained with chain drive transfer cases, but it was something. In my case, It will cost me turning those heavy gears all the time in the Atlas.:sad0147:

[Mudderoy]

Death and taxes are a given, unless you are a US Congressman then you can eliminate taxes:eek:

When we got fancier with our 4X4s we paid a price in milage. Full time costs about 3 mpg. No hubs about 1.5 - 2 Mpg. I don't know what we gained with chain drive transfer cases, but it was something. In my case, It will cost me turning those heavy gears all the time in the Atlas.:sad0147:

Well as I mentioned in the post about Xtreme 4x4 MPG series, I'm going to be watching what they do to that truck, and hopefully I'll learn something from it. Currently I'm thinking a 1999 intake, a larger throttle body and matched rebuilt fuel injectors. Oh and that cowl induction hood to get the heat out from under the hood.

I also have a bent exhaust tube, well I guess more of a big notch that I'm going to replace. The exhaust guy said it wasn't a problem, but I think I'm losing 25% of the internal surface area that lets the exhaust out. Ok maybe 15%. I don't like that notch.

[4.3LXJ]

I have always thought that the XJ exhaust systems were restrictive. They put the same size system on my original 2.8L as they did the 4.0. Also the intake is restrictive. The throttle body on my 4.3 is a full 3". On a 5.7 it goes to 4". The injector thing will be good. Are you using the four nozzle injectors?

One other thing you can't get away from in a 4.0 is balance. They just are not balanced properly. Instead of having a balanced crank, they balance them with different weights on the pistons. That also eats a little horsepower. Balance gets you 1 mpg.

[Mudderoy]

I have always thought that the XJ exhaust systems were restrictive. They put the same size system on my original 2.8L as they did the 4.0. Also the intake is restrictive. The throttle body on my 4.3 is a full 3". On a 5.7 it goes to 4". The injector thing will be good. Are you using the four nozzle injectors?

One other thing you can't get away from in a 4.0 is balance. They just are not balanced properly. Instead of having a balanced crank, they balance them with different weights on the pistons. That also eats a little horsepower. Balance gets you 1 mpg.

I have the original injectors. They are 2 nozzle I think. The rebuilt ones I am looking at are 4 nozzle.

[4.3LXJ]

If I am not mistaken, your OEMs are single nozzle

[Mudderoy]

If I am not mistaken, your OEMs are single nozzle

Wow! That sucks!

[4.3LXJ]

Wow! That sucks!

That is why the other 4 nozzle injectors are such an upgrade. The gasoline evaporates more easily for better and cleaner burning.

Something else on my list of things to try is a pint of acetone in each fill up. It makes the gasoline evaporate better and gives a boost in milage. The ethanol they put in here hinders it and gives us a 2 mpg drop for any vehicle.

[Mudderoy]

That is why the other 4 nozzle injectors are such an upgrade. The gasoline evaporates more easily for better and cleaner burning.

Something else on my list of things to try is a pint of acetone in each fill up. It makes the gasoline evaporate better and gives a boost in milage. The ethanol they put in here hinders it and gives us a 2 mpg drop for any vehicle.

I think I read somewhere that acetone causes rubber hoses to deteriorate.

[4.3LXJ]

I have heard that also. But n the other hand, I have an old friend that ran straight acetone in his circle burner with no ill effects.

[TheWeiss]

Have any of you guys noticed an actual mileage difference because of the injectors? The logic is sound but plenty of other things have sounds logic but no gains. I switched to all electric fans thinking it would help and while it gave the old Jeep a little more get-up-and-go and vastly improved the sound of the engine. It didn't make a dent in my gas mileage.

*** Also of note, that was the first thing they did on Extreme... although I think the fan on the Dodge was clutc less so the electric should be more beneficial.

[HarleyRider]

My average is 16 mpg. :boohoo:

[xjarcher]

A pint of acetone is too much. In a 20 gal. tank you want about 4 OZ. It will clean the system and you will get a mpg or two better. I usually trat my Expy to some before we take a trip. Gets me all the way up to 14 mpg!:cheerleader:

[xjredneck]

ok everyone the unthinkable has been done!!!! i got over 357 miles to one 18 gallon tank of gasoline i never knew it could happen... but when you cruise at 75 mph from maine to new york its possible!!!!!

[firehawk]

I recently drove from Indy to Milwaukee in the Jeep. In third doing a GPS indicated 62 mph, and spinning right at 2500 rpm I got 16 mpg. I know it will do better in OD, but it lugs the engine too much with my 3.55 gears and 31" tires.

[xjredneck]

i got 3.55 and 31's i dont have a problem with it od

[W.O.R.P.Offroad]

when i went to tn the last time in the jeep my tcu was actin up so i had no OD and was on 33 with 3.55:1 i got 10mpg that sucked on a 500 mile each way trip

[firehawk]

i got 3.55 and 31's i dont have a problem with it od

I can drive it ok in OD, but in my case at 60-65 mph it is only turning 1900-2000 rpm. That seems to be low, I have no real power until I'm over 2000 rpm. It will want to downshift on hills on the interstate. It appears that the AW4 won't just shift out of OD, but goes down to 2nd. It will upshift twice once into 3rd then back into OD. IMO that would kill mpg.:confused:

[Mudderoy]

I can drive it ok in OD, but in my case at 60-65 mph it is only turning 1900-2000 rpm. That seems to be low, I have no real power until I'm over 2000 rpm. It will want to downshift on hills on the interstate. It appears that the AW4 won't just shift out of OD, but goes down to 2nd. It will upshift twice once into 3rd then back into OD. IMO that would kill mpg.:confused:

32" tires with 3.55 gears is funky going over overpasses. 4.56 much much better. I really need those larger tires though. 3000 rpm at 80 mph in over drive.

[firehawk]

32" tires with 3.55 gears is funky going over overpasses. 4.56 much much better. I really need those larger tires though. 3000 rpm at 80 mph in over drive.

If there is one thing I've learned about lifting a vehicle and going with larger tires is, regear first BEFORE you do ANYTHING!

MAN you drive fast. I can't think of anywhere I need to be that I would have to drive at 80 mph. I know I've seen on here you sometimes drive at or over 100 mph? Anyone checked what the speed rating for BFG AT's are?:shocker:

I'm just old I guess. I drove 70 mph last year (the speed limit) to meet a buddy to go hunting. I felt I was flying!:eek:

[Mudderoy]

If there is one thing I've learned about lifting a vehicle and going with larger tires is, regear first BEFORE you do ANYTHING!

MAN you drive fast. I can't think of anywhere I need to be that I would have to drive at 80 mph. I know I've seen on here you sometimes drive at or over 100 mph? Anyone checked what the speed rating for BFG AT's are?:shocker:

I'm just old I guess. I drove 70 mph last year (the speed limit) to meet a buddy to go hunting. I felt I was flying!:eek:

I'm going to have to do a video for you guys. My luck I'll get pulled over and taken to jail. lol

When I first got the Jeep I would drive in "in bursts" 80 to 95 mph daily going to and from work. That torque was great. I know this will sound insane to you, but I try to drive safely. I don't like whipping in and out of traffic for position, but I would certain get around someone, or a group of cars and accelerate around them and then drop back down to 75ish.

It makes a big difference when you are in a big city where 80 to 85 is at least 50% of the traffic flow. If you keep in mind that say 78 is the average speed of the fast lane, then 85 to 95 makes more sense.

I remember I was in Boston attending a training course. I got compliments on my aggressive driving skill as I wasn't intimidated by the Boston drivers. The only place I've ever been that I was intimidated was Monterey Mexico. That probably wouldn't have been so bad if the wife wasn't in the truck with me at the time. lol She makes me nervous. Flinches and holds on too much. :rotfl2:

[pkbinder]

I recently had my NSS cleaned up and I got an unexpected benefit. Before the cleaning whenever I used cruise control over 62 mph it was constantly dropping down into 3rd (passing gear). After cleaning I can set it at 70 or higher and it pretty much stays in the "overdrive", except on hills.

[Mudderoy]

I recently had my NSS cleaned up and I got an unexpected benefit. Before the cleaning whenever I used cruise control over 62 mph it was constantly dropping down into 3rd (passing gear). After cleaning I can set it at 70 or higher and it pretty much stays in the "overdrive", except on hills.

I don't understand why this would make a difference.

[suzq044]

So far, according to my Droid, our milage breaks down to a solid 22/18 highway/street. We have the 2.5l 4banger with a 5spd stick though.

Also, here in san diego, avg speed varies by which freeway you are on. The15 your avg is 80+, on the 5 its around 70mph..

[Mudderoy]

As you may have read I changed out the stock 4.0L injectors for some Ford Mustang injectors. I haven't noticed any difference but I just changed them and I've only put about 25 miles on them so far.

I was out working on the Jeep this early evening and since I had the laptop and OBD II interface out there I decided to do a quick check of the O2 sensor information.

I started up the engine and started collecting data. I ran the rpm up to 2000. I had a nice surprise. Previously I was seeing the O2 sensor 1 data doing a saw tooth pattern between .5 and .75 volts. I was told this was high and it indicated that my motor was running rich. Once possible explanation could be a leaky injector.

Now I need wider voltage range sawtooth pattern. From .02 to .8 volts. If my memory serves this is the normal pattern. I'll probably load up the laptop and collect real driving data going to work this coming week.

My mpg is 13.8 as a high (city) and only about 14.5 for highway. 13.8 is current config the 14.5 was with 3.55 gears.

So I don't want to jump and say it's fixed, but I certainly like the data I'm seeing. I'll know more next Friday when I'm hitting the 215-230 miles mark. 230 miles is the max range I can get from my 18 gallon tank.

[Mudderoy]

Current gas mileage.

I filled up this morning so I could get a good idea of the mpg for the week, after the injector installation this past weekend.

http://xjtalk.com/images/special/jeepgasmileage2010.jpg

It seems that my gas mileage is worse when I fill up before I am say down to 1 or 2 gallons in the tank. In other words my MPG seems to increase the less fuel I have. The only thing that comes to mind is weight. Now this last fill up may be accurate in as much as I ran the engine at 80 and 90 miles per hour over the weekend. Not for a really long time, but I've noticed seeing (almost) the gas gauge needle move when I was driving at 100+ before. lol

I'll be driving normal "city" this week to and from work. If I see anything above 13.8 mpg then the injectors are most likely the culprit.

I've been collecting MPG data since July of 2008, so I'll notice any big jump in mpg.

As part of my MPG data collection ritual I always fill up, jot down the date, the mileage from the odometer, and the number of gallons it took to fill up. Then I reset the odometer to 0.
This means that as I'm driving during the week I can get a feel for how well the MPG is. For example a 1/4 tank should be around 80 miles. 1/2 tank should be around 150 miles. 3/4 tank around 185 miles. I get about 45 miles to a 1/8 of a tank. That's an estimate because it depends on if the gauge is +1/2 or -1/2. Needle goes down faster after the 1/2 tank mark.

Those who are curious, I do NOT top off the tank. I try to use the same gas station and the same pump. I fill until the auto shutoff triggers. The most fuel I have ever got into my 20 gallon tank is around 18.2 gallons.

[Bigdaddy]

I've got a 1992 4.0L H0, AW4, 235 75 r15's, no lift, winch bumper, winch, thule bars.

I generally get about 265-270 before I fillup. when I fill I never get more than 15 gallons into my 20 gallon tank. A common problem, I've heard. (The reason that I'm thinking that I have the 20 gallon tank cuz when I first got the truck, I could put around 18 gallons in it, before it clicked off. :))

Would it be fair to say that I"m getting 265-270 on 15 gallons, since I never fill up more than that? If so, my mpgs are around 18.3 or so.

If I let my tank run dry, I'd be looking to get around 360 miles from a tank @ 18mpg.

That being said, I honestly don't really care to spend much more time figuring it out on a daily basis(though I love the effort put into this thread by the OP, no offense intended. very good info there!!)...

Jeep = paid off
Ins. = very cheap (comp/collis & liability w/ AAA)
mods = cheapest off the shelf/bolt-on parts of any rig I've owned.
maint. = about $600 in the year i've owned it, including a 120.00 lifetime warranty, alum. radiator from pep boys, and $200 in baseline preventative maintenence.

Oh, and my 1992 rig has only 175,000 miles. Thats only 9722 miles per year on average. You should see my interior. It's almost mint. :thumbsup:

I love this truck.

-Brian

[Mudderoy]

I was about a needle's width away from 3/4 tank (towards the Full side) this morning at odometer read 86 miles. The gauge acts kind of funky while you are driving the Jeep, in as much as it seems to drop more once you stop. It may be that it is giving your an average so you don't see the needle moving around.

Anyway I noticed it was at 90+ miles when the needle was directly on 3/4 of a thank, but when I got to work I was about 1/2 way between 3/4 and the next 1/8 tank mark down, and 105 miles.

I know I just need to wait until Friday when I get to 200+ miles and see where I am then. I'm going to keep looking! lol

When she gets good gas mileage 3/4 tank is about 80 miles, so 90 is better!

http://lh4.ggpht.com/_b0ViaGso2Ko/S89D5EawLgI/AAAAAAAAAD4/nOmZt6kKukg/s912/2010-04-21%2008.42.29.jpg

[W.O.R.P.Offroad]

we will see. i know there is usually a 1 to 3 mpg increase sometimes more sometimes none

[Mudderoy]

Well it looks like my gas mileage was better for the first 1/4 of a tank, but it now back to normal. I've seen this before. I disconnect the battery for 30 minutes, or so, and gas mileage seems to improve but by 1/2 tank things are back to normal. Maybe I need to look into that clearing procedure that was posted earlier in the thread.

http://lh6.ggpht.com/_b0ViaGso2Ko/S9BQwkXH-VI/AAAAAAAAAEU/RbA4Sj1Asck/s576/2010-04-22%2008.33.34.jpg

BTW, both this and the picture above were taken at the same intersection.

[Mudderoy]

So tomorrow is the big day. I have about 1/8 of a tank more fuel that I would normally at this time. Not near as much as I was hoping but more is more.

I thought about waiting until tomorrow evening to do the PCM reset (as per the instructions in my injector replacement thread) but I did it today. It screws up my mpg measurement, right? Yes but it will also tell me something that I have come to wonder about.

It seems that I get better gas mileage after I reset the computer. Of course I always "think" I notice it on the upper end of the fuel gauge, so I thought resetting the computer at over 1/2 the tank used, if I get lots more miles out of the Jeep I'll know that resetting the computer is making a difference.

Then it hit me. If it does improve the mpg, that means the computer is running off of it's internal factory default settings. After a few days the mpg starts dropping. This is probably due to a bad sensor. I can reset the computer, record data from the sensors then when I get below 1/2 tank I can record the data again and compare the results.

Giving the same conditions I may be able to see what sensor(s) data is changing.

Of course the other thing I can do is reset the computer daily and see what that does to my mpg.

I'm going to beat this horse to death until I fix the damn thing!

:deadhorse:

[4.3LXJ]

Stop and think about this a little. 1/8 tank might not seem much, but percentage wise that is 12% increase. That in itself would be respectable.

[Mudderoy]

http://lh3.ggpht.com/_b0ViaGso2Ko/S9GqMbec29I/AAAAAAAAAFI/B298OSb0JGc/s640/2010-04-23%2008.35.40.jpg

Remember I reset the computer last night so the mileage here is actually 181.2.

I'd say at this point I'm not seeing any improvement in mpg from stock injectors to the new ones. 185 to 187 miles is what I'd expect to see with 1/4 tank left.
I know one measured tank of gas isn't enough data to determine a "small" improvement. I was hoping that I had found the problem and there would be a large improvement.

[Mudderoy]

http://lh5.ggpht.com/_b0ViaGso2Ko/S9IrNIGCX3I/AAAAAAAAAGg/sgLeZ3oyVbE/s512/2010-04-23%2018.15.18.jpg
This one was taken after I got home on Friday.

So total miles was 204.7 for the week. I can make it home on 1/8 of a tank from work, and that is 19.5 miles. So that would put me at 225 miles on a tank. Of course I don't know how much is left.

I'll guestimate about 13.3 mpg which if the trend continues I might be 1 mpg better.

I ordered the Performance Distributor FireWire kit about an hour ago. I should get another week of mpg data before I install it.

[Mudderoy]

Okay I just went and purchased some fuel. I was hopeful that the mileage would be better since I only had to put in 16.64 gallons, but it was only better than last time.

http://xjtalk.com/images/special/jeepgasmileage2010.jpg

About 12.5 mpg. Of course it takes more than one measurement to get the overall sense of the mpg gain.

[Mudderoy]

In an effort to remove the "I think" and replace it with factual data I have been taking photos at each 1/8 tank (approx.)

7/8 tank - 80 miles
http://lh6.ggpht.com/_b0ViaGso2Ko/S9X9QQBbpCI/AAAAAAAAAJQ/3_Q_fF2Da_w/s512/2010-04-25%2012.11.48.jpg

3/4 tank - 100 miles
http://lh6.ggpht.com/_b0ViaGso2Ko/S9X9FqQqCdI/AAAAAAAAAJM/OZgjzQ-F8ds/s512/2010-04-26%2008.33.13.jpg

5/8 tank - 120 miles
http://lh3.ggpht.com/_b0ViaGso2Ko/S9b9C4S9MpI/AAAAAAAAAJY/H0RYKJ2hfZI/s512/2010-04-26%2018.07.22.jpg

1/2 tank - 140 miles
http://lh4.ggpht.com/_b0ViaGso2Ko/S9b35FvBnzI/AAAAAAAAAJU/dkIrBz4n_SE/s512/2010-04-27%2009.00.30.jpg

3/8 tank - 160 miles
http://lh4.ggpht.com/_b0ViaGso2Ko/S9hAk8sccDI/AAAAAAAAAJg/4jSmP2LtxdQ/s512/2010-04-28%2007.47.08.jpg

1/4 tank - 180 miles
http://lh5.ggpht.com/_b0ViaGso2Ko/S9mLn5skRoI/AAAAAAAAAJ4/iNelwocvUrU/s512/2010-04-28%2017.41.05.jpg

1/8 tank - 200 miles
http://lh4.ggpht.com/_b0ViaGso2Ko/S9mL7F_W1oI/AAAAAAAAAKA/ni1zkQREJ8c/s512/2010-04-29%2008.28.52.jpg

Empty - 220 miles

Next time you fill up, press the reset on your trip mileage odometer and report how you stack up!

[1994xjsport]

32" tires with 3.55 gears is funky going over overpasses. 4.56 much much better. I really need those larger tires though. 3000 rpm at 80 mph in over drive.
I feel good going 85 at 2200 rpm then and i can usually get around 25 on the interstate i drive 500 miles round trip every weekend so it helps

[W.O.R.P.Offroad]

so did you act see a difference ?

[Mudderoy]

so did you act see a difference ?

I'm only at 1/2 a tank. My estimates don't show any mpg difference.

[W.O.R.P.Offroad]

have you had 50 warm up cycles yet?

[Mudderoy]

have you had 50 warm up cycles yet?

Since last Thursday? No, maybe 20. I would expect to see different mpg that what I was getting before though.

[rguignard]

well muddy this is what mines getting so far on this tank

http://i694.photobucket.com/albums/vv303/rguignard001/8e1ccaa8.jpg

it says 153 at this point

http://i694.photobucket.com/albums/vv303/rguignard001/077648e0.jpg

[Mudderoy]

I thought this was interesting. I kept watching the gas gauge this morning after I took the picture of 3/8 of a tank and didn't notice the needle moving much. I went nearly 10 miles on about a needles width of the gauge. Now this may just be due to inaccuracies in the gauge, or sending unit as the float gets to the bottom of the tank.

http://lh5.ggpht.com/_b0ViaGso2Ko/S9hAVUET4CI/AAAAAAAAAJc/lw7_Q0nUObk/s512/2010-04-28%2008.10.38.jpg http://lh4.ggpht.com/_b0ViaGso2Ko/S9hAk8sccDI/AAAAAAAAAJg/4jSmP2LtxdQ/s512/2010-04-28%2007.47.08.jpg

[Mudderoy]

I recorded data driving in to work this morning. My "Check Engine" light came on yesterday, so after getting to work I checked the code. I had 4 of them.

P0300
P0302
P0304
P0305

Basically they are all mis-fires. 302 is cylinder 2, 304 is cylinder 4 and 305 is cylinder 5. So either the cables are all starting to fail, or I have a bad rotor, rotor cap, or the head gasket is REALLY going bad.

[4.3LXJ]

Muddy

I may be mistaken, but I think that the ECM reads misfires on the injectors and not the plugs. My logic for what it is worth is based on the idea that only the injectors are individually connected to the ECM and therefore measurable due to resistance in the injector coil.

[Mudderoy]

Muddy

I may be mistaken, but I think that the ECM reads misfires on the injectors and not the plugs. My logic for what it is worth is based on the idea that only the injectors are individually connected to the ECM and therefore measurable due to resistance in the injector coil.

Thanks, I'll do a little research. I certainly hope this isn't the case, what with my new injectors and all.

[Mudderoy]

Here is the Oxygen Sensor 1 data I collected going to work this morning.

http://xjtalk.com/images/special/Jeep_Gas_Mileage2.jpg

The average voltage reading is about 5.6 volts.

But comparing it to this old graph, I see that when I was trying around 2000 rpm the voltage sweeps between .1 and .8 volts. But when I'm driving around 2800 rpm it varies between .7 and .8 volts.

http://xjtalk.com/images/special/EngineO21_Test1.jpg

I need to collect some data at 70 to 80 mph now.

[Mudderoy]

You'll have to go back a page to see the updated pictures for 1/4 tank, etc...

Something strange happened between 3/8 and 1/8 of a tank. I drove about 33 miles. Normally 20 to 22 miles for 1/8 of a tank. Again it could be inaccuracies in the sensor, but I would expect to have seen a lower fuel reading eventually.

http://lh4.ggpht.com/_b0ViaGso2Ko/S9hAk8sccDI/AAAAAAAAAJg/4jSmP2LtxdQ/s512/2010-04-28%2007.47.08.jpg http://lh5.ggpht.com/_b0ViaGso2Ko/S9mLn5skRoI/AAAAAAAAAJ4/iNelwocvUrU/s512/2010-04-28%2017.41.05.jpg

I'm a little less that 1/8 of a tank now, so I'll be watching it like a hawk since I need 1/8 of a tank to get home!

lol I lied! I just went back and looked at the picture...

http://lh6.ggpht.com/_b0ViaGso2Ko/S9mY6jEeImI/AAAAAAAAAKE/4k1FA4co38Q/s640/2010-04-29%2008.38.30.jpg

I think I better stop and get some fuel on the way home. :rotfl2:

[Mudderoy]

Final miles was 227. I filled the tank with 17.57 gallons which is 12.9 mpg

[rguignard]

heres my gas mileage for this tank

http://i694.photobucket.com/albums/vv303/rguignard001/819d3675.jpg

http://i694.photobucket.com/albums/vv303/rguignard001/80dc3567.jpg

just about 16 mpg with the tires making the speedo wrong

[Mudderoy]

Hmmm well I may have assumed the worse, no change in mpg, prematurely.

As you can see from the latest mpg graph gas used per mile is sharply up.

http://xjtalk.com/images/special/jeepgasmileage2010-4.jpg

I guess this is why when making changes to improve gas mileage you need to have a few days, or weeks, of measured data before making the next change.

13.75 mpg is my best since July 2008.

[4.3LXJ]

You're just going to have to drive more and get some more data. Two points don't count, but are promising.

[BrianXJ]

any new developments in the change since the new injectors. kinda of dropped off

[Mudderoy]

any new developments in the change since the new injectors. kinda of dropped off

lol nope, nothing ever changes the mpg on my Jeep. I'll update the graph. She seems to like to cooler weather more, or it could be that it's just because the A/C isn't on.

[bluedragon436]

http://lh6.ggpht.com/_b0ViaGso2Ko/S9mY6jEeImI/AAAAAAAAAKE/4k1FA4co38Q/s640/2010-04-29%2008.38.30.jpg

Mine always looks like this... damn fuel level sending unit!!

[Mudderoy]

Final MPG for 2010

Average was 12.29 mpg

http://xjtalk.com/images/special/jeepgasmileage2010-12.jpg

[Mudderoy]

2011 mpg to date

Average 12.25 mpg

http://xjtalk.com/images/special/jeepgasmileage2011-5.jpg

[prerunner1982]

Ouch!

[Mudderoy]

2008
(01/2008 O2 sensors changed)
(6/9/2008 changed from 3.55 to 4.56 gears! 06/21/2008 13.03 mpg!)
http://xjtalk.com/images/special/jeepgasmileage2008.jpg

2009
http://xjtalk.com/images/special/jeepgasmileage2009.jpg

2010
http://xjtalk.com/images/special/jeepgasmileage2010-12.jpg

2011
http://xjtalk.com/images/special/jeepgasmileage2011-5.jpg


NOTHING

I have done has made a DAMN bit of difference to my gas mileage since changing the gears!

I have added a custom rear bumper, a custom front bumper, winch, 32" spare tire, 4 6" KC lights and the gas mileage has been very steady!

Actually I'll back up a little on that statement. MPG has gone down slightly, perhaps .2 mpg looking at the average.

I have made changes that could have balanced out the additional weight I added. (multi port fuel injectors for example)

[prerunner1982]

I realize mine is not as long as yours.... but wanted to post it anyways. :D

http://www.xjtalk.com/picture.php?albumid=227&pictureid=2382

[XJ Rat]

University & Highway 6 in Missouri City, there are a couple stations that have regular for $3.81 per gallon. One of those stations is a Krogers so if you have a Kroger card, you will save 3 cents minimum.

Bottom line is I just filled my truck up for $3.78 a gallon.

I can remember going to the station with my dad. There were signs spray painted on 4x8 sheets of plywood 'GAS WARS'. The gas was 24 cents per gallon. That was a loonnnnnng time ago.

[Mudderoy]

University & Highway 6 in Missouri City, there are a couple stations that have regular for $3.81 per gallon. One of those stations is a Krogers so if you have a Kroger card, you will save 3 cents minimum.

Bottom line is I just filled my truck up for $3.78 a gallon.

I can remember going to the station with my dad. There were signs spray painted on 4x8 sheets of plywood 'GAS WARS'. The gas was 24 cents per gallon. That was a loonnnnnng time ago.

46 cents a gallon was the lowest I ever paid.

[Mudderoy]

I'm going to start an experiment Sunday evening that will run Monday through Friday next week.

I've noticed during past repairs that needed to have the ECM reset my gas mileage is better (I go further on less gas as noted by the gas gauge) for the first couple of days (88 miles).

So I'm going to reset the ECM on Sunday evening. Drive Monday and Tuesday then reset the ECM Tuesday evening. Drive Wednesday and Thursday, then reset the ECM again.

I think I have one or more sensors that is telling the ECM to give me worse gas mileage. Resetting the ECM back to factory defaults should cause it to stay with the unlearned parameters, at least that's what I've gathered over the years.

[Jamie Lynn]

http://lh6.ggpht.com/_b0ViaGso2Ko/S9mY6jEeImI/AAAAAAAAAKE/4k1FA4co38Q/s640/2010-04-29%2008.38.30.jpg

Mine always looks like this... damn fuel level sending unit!!

Mine can get funny like that too sometimes...eventually it will get fixed.

[Metlic53]

Just wondering muddy, but why 4.56 gears? I've got 3.55 gears and i run 60-70 mph alot and at 70 i'm turning right at 2100 rpms, with those 4.56's you've gotta be screamin going 60 i would imagine. I bet you would get better mpg with 4.10, I got 17 on this last tank and it was all city driving, that was with a set of 33's that a buddy of mine let me borrow to see how my jeep would do with 33's.

[jeepxj95]

hey tony did you recalibrate ur speedo? mine was 15 mpg be4 and now im getting around 18 to 20 with 31s and 3.55 gears after i recalibrated my speedo

[Mudderoy]

Just wondering muddy, but why 4.56 gears? I've got 3.55 gears and i run 60-70 mph alot and at 70 i'm turning right at 2100 rpms, with those 4.56's you've gotta be screamin going 60 i would imagine. I bet you would get better mpg with 4.10, I got 17 on this last tank and it was all city driving, that was with a set of 33's that a buddy of mine let me borrow to see how my jeep would do with 33's.

I think I calculated that a 4.20 gear would have been best for my future 33" tires.

Basically the fine folks on NAXJA said go one lower, you'll wish you had otherwise.

4.10 was the original plan though.

80 mph = 3000 rpm

[Mudderoy]

hey tony did you recalibrate ur speedo? mine was 15 mpg be4 and now im getting around 18 to 20 with 31s and 3.55 gears after i recalibrated my speedo

Yeah that's buried in there on one of the posts. I corrected the ratio each time with a new speedo gear in the transfer case.

[LizardRunner]

the higher the rear gears, the more revolutions the engine must make to turn the tires one full revolution. If you're going to do a lot of rock climbing, like most of the NAXJA guys are into, then yes you would want the taller gears. If you do a lot more mudding than rock crawling, 4:11 gears are better for 33's cause you want to be able to turn them over faster. a lot of your mileage loss is due to those gears in your pumpkins. I currently have 3:55 gears and am getting about 18 mpg. I doubt that I'll go any taller than 4:11's ever, I don't do mostly rock crawling.

[Mudderoy]

the higher the rear gears, the more revolutions the engine must make to turn the tires one full revolution. If you're going to do a lot of rock climbing, like most of the NAXJA guys are into, then yes you would want the taller gears. If you do a lot more mudding than rock crawling, 4:11 gears are better for 33's cause you want to be able to turn them over faster. a lot of your mileage loss is due to those gears in your pumpkins. I currently have 3:55 gears and am getting about 18 mpg. I doubt that I'll go any taller than 4:11's ever, I don't do mostly rock crawling.

If you didn't read from the beginning, I was getting 10 mpg with 32's and 3.55 gears. My mpg increased going to 4.56 gears, by nearly 2.5 mpg.

[4.3LXJ]

Tony

Just for the sake of discussion, I think we have a good thing to add to the "what gears should I have" threads. Most of the time, people will advise going to the next numerically higher ratio to help the butt dyno or off road performance. However most people when advising for gear ratios are using the 65mph target for on road gearing. However in many areas, such as CA and TX as well as many other states, the average speed on four lane highways is now 80 mph in spite of what the posted speed limit is. Here in CA, you don't get stopped till you hit 85 or 90 mph. I think that in your case since you are driving as much on the highway as you are, you would have been better off with 4.10s. I am not sure how much better your milage would have been, but I think you would have seen maybe an additional .5 mpg. Driving at 80 mph, even a prius doesn't get near what it is supposed to.

[LizardRunner]

I was just throwing out the resons for gear changes tony. my hill climber GTO had a quick change box, I could go all the way up and down pretty fast. I had some 4:11's for the street and three different sets to use for racing up the mountains. for pikes peak as an example I would use something close to 5:07 for a straight line drags setup I had 5:44 these vehicles are very different than that GTO, I'm sure you will be able to get more mileage with the data your collecting. It's interesting that you are getting better mileage with the taller gearing, usually it goes downhill. but a lot of mileage is how you drive too. Me and my lead foot are pretty happy with what I am getting right now and I pretty much expect it to go down as I add heavier bumpers, sliders, etc. after all it's a straight six I'm expecting to power my rig, that tells me it will need more fuel to do what I want it to do. on the other hand, I also use my bike for most of my driving when the weather allows.

[Metlic53]

The only reason i asked was because i asked my dad if i should go to 4.56's when i get my 33's and he said, "4.10's is the highest i would go, 4.56's are fun to putt around in, but if it is a daily driver jeep and occasionally a trail rider then don't put 4.56's in it". He basically told me, their good for the quarter mile and slow cruising, (unless you've got 36" or bigger tires). I just figured a 4.10 would net the greatest amount of mpg you could get with a 33 inch mudder from what i've heard. Although i bet you could whoop me off the line :D

[Mudderoy]

The only reason i asked was because i asked my dad if i should go to 4.56's when i get my 33's and he said, "4.10's is the highest i would go, 4.56's are fun to putt around in, but if it is a daily driver jeep and occasionally a trail rider then don't put 4.56's in it". He basically told me, their good for the quarter mile and slow cruising, (unless you've got 36" or bigger tires). I just figured a 4.10 would net the greatest amount of mpg you could get with a 33 inch mudder from what i've heard. Although i bet you could whoop me off the line :D

It's a hard decision. It's very expensive and you don't want to look back and say I should have done ...

I remember one of the discussions was the high RPMs that the 4.0L would be turning. I think I was estimating 3000 rpm at 80 mph, and at least one person said the 4.0 will turn 3000 rpm all day long.

Keep in mind too that the main reason for changing the gears was to help improve the MPG.

4.10 was my original choice, but getting feedback from everyone I went with the 4.56. It's an off road vehicle, so you do have to pay to play. I know that, I mean I could always put it back the way it was for less than $500. Just go buy some stock axles wheels and tires.

[prerunner1982]

Tony.. I know it is a long shot, but do you think it would be possible to find a 4.10 gear rear axle from a 4 cylinder XJ to swap in for test purposes? Run around in 2wd for a couple of weeks and see if the mpg changes... (up...down...???)

Also based on the gear ratios of the AW4 I would believe it would benefit more from the 4.56s, at least around town as it only has a 2.80 first gear. Where the AX15 has a 3.83 first gear and would be fine with the 4.10 ratio. I believe the 3000rpms is what may be bringing the mpg down. I don't run on the highway so I can't compare my highway mileage to yours. My mileage is 40 miles a day with stop signs/lights every mile. My RPMs are kept low. I shift at 2000 or so and at constant speed I keep it at 1500 or so, sometimes a low as 1200.

[prerunner1982]

Interestingly enough... if we (Tony and I) both had the same sized tires and the same drive train as we do now we would have very similar overall gearing ratios, at least through the first 3 gears..

1st gear:
Prerunner Mudderoy
Trans 3.83 2.80
T-Case 1.00 1.00
Axle 3.08 4.56
Over all 11.7964 12.768

2nd gear:
Prerunner Mudderoy
Trans 2.33 1.53
T-Case 1.00 1.00
Axle 3.08 4.56
Over all 7.1764 6.9768

3rd gear:

Prerunner Mudderoy
Trans 1.44 1.00
T-Case 1.00 1.00
Axle 3.08 4.56
Over all 4.4352 4.56


Tony I realize this does not help you much if at any. I just thought that it was interesting that I could run my set up with 32"s and be almost equal to your current set up at least in the low end.

[Mudderoy]

Tony.. I know it is a long shot, but do you think it would be possible to find a 4.10 gear rear axle from a 4 cylinder XJ to swap in for test purposes? Run around in 2wd for a couple of weeks and see if the mpg changes... (up...down...???)

Also based on the gear ratios of the AW4 I would believe it would benefit more from the 4.56s, at least around town as it only has a 2.80 first gear. Where the AX15 has a 3.83 first gear and would be fine with the 4.10 ratio. I believe the 3000rpms is what may be bringing the mpg down. I don't run on the highway so I can't compare my highway mileage to yours. My mileage is 40 miles a day with stop signs/lights every mile. My RPMs are kept low. I shift at 2000 or so and at constant speed I keep it at 1500 or so, sometimes a low as 1200.

I don't think it would be worth me spending $200 (or more for a rare 4.10) rear axle. I'd be better off just buying a set of 35" tires.

Shipping weights for 4 tires are as follows....

BFG MT KM2
32" 50 lbs
33" 58 lbs
35" 59 lbs

That's not per tire, that's for 4!

I would be very interesting in seeing what the 4.10 axle would do mpg wise though.

[prerunner1982]

No trickery here... this is as of a few mins ago. Not trying to brag (ok maybe a little), just more proof that it can be done.

http://www.xjtalk.com/picture.php?albumid=211&pictureid=2470

[Mudderoy]

No trickery here... this is as of a few mins ago. Not trying to brag (ok maybe a little), just more proof that it can be done.

http://www.xjtalk.com/picture.php?albumid=211&pictureid=2470

Bragging is fine especially when it shows a positive goal.

[jeepxj95]

sould of took a pix when i filled up it was 403 miles and took 20 gallons. almost didn't make it to the gas station. usally get 18-19 mpg

[junglejuice]

I can get near 1000 kilometres per tank of petrol which equates to around 24mpg or 12l/100....


I do have a 125l petrol tank though...

[jccatt]

I get 17l/100km :bang:

[jeepxj95]

sorry guys but whats that in mpg? or a little converion plz

[saar]

2001 xj, 245/75/16 stt copper tires.
roof rack (spare tire on it)
~5 km for 1 liter.
= 1 liter for 3.125 miles
Saar

[bobalou]

Hi I'm new here. I just got back from buying a Jeep in Utah. It's a '94 Cherokee Sport. This is my first jeep since I had charge of two radio jeeps in the Marine Corps in '64, so it's all pretty new to me. At age 70, I'm putting less mileage on the motorcycles, so the Jeep will get me out more often, I hope.

Anyway, the trip home was a lot of fun. 1,395 miles total. About 50 miles on dirt roads ranging from excellent to I-wouldn't-drive-the-family-Volvo-there. And I stopped off at "the Sump" in Esmeralda County NV and took it off road for a few miles.

The overall mileage for this trip was 19.1 mpg. I mostly drive at speed limit, or 65 (whichever is higher).

Bob

[Mudderoy]

Hi I'm new here. I just got back from buying a Jeep in Utah. It's a '94 Cherokee Sport. This is my first jeep since I had charge of two radio jeeps in the Marine Corps in '64, so it's all pretty new to me. At age 70, I'm putting less mileage on the motorcycles, so the Jeep will get me out more often, I hope.

Anyway, the trip home was a lot of fun. 1,395 miles total. About 50 miles on dirt roads ranging from excellent to I-wouldn't-drive-the-family-Volvo-there. And I stopped off at "the Sump" in Esmeralda County NV and took it off road for a few miles.

The overall mileage for this trip was 19.1 mpg. I mostly drive at speed limit, or 65 (whichever is higher).

Bob

lol wow what a trip! Kind of makes you wonder why anyone buys a new vehicle!

[jeepxj95]

i wouldn't they dont look good any more and to many electronics and big brother. and I LOVE MY 95 XJ would never sell it. i would park it first.

[bobalou]

i wouldn't they dont look good any more and to many electronics and big brother. and I LOVE MY 95 XJ would never sell it. i would park it first.
Yeah, my last new car was a '72 Toyota pickup, which I used to haul hay for the horses, and to pull the horse trailer. Horses are long gone though.

I agree, I like the looks of the xj, and if I quit driving it, I'll park it out front where I can look at it (with my motorcycles.)

I was a bit surprised at the gas mileage though. I think the EPA is only reporting about 17 mpg average on the highway. From this thread, it looks like folks are doing better than that. I sure did. Of course, you need to run it over a few tanks, because every fillup may be to a different level.

Bob

[Paddletrucker]

I'm half way through my second tank since getting my XJ. She has the 4.0 and 5-spd manual tranny. It has a little over 207K miles. The A/C isn't working yet, so I haven't been running that, and I usually drive 60-62 or so.

On the first tank, I showed 24mpg's, but I'm thinking that's too high. I can't verify that the tank was completely filled the first time. I don't remember topping it off.

The second tank, though, I was paying attention. I filled it all the way up, and I'll monitor my mileage good from here on out. That way, I'll know what I'm dealing with when I buy different tires and a lift.

Right now, I've got 240 miles and I still have just a touch more than a half of a tank, so we'll see.

[prerunner1982]

That's excellent. Of course... once you lift it and put larger tires it will only go down, but even if you lose 3-4mpgs you are still doing better than most XJs.. even stock ones.

[Paddletrucker]

Well, we'll see. Right now, I can just say definitively that I know it will be cheaper to drive than my pick ups. The 24 is almost assuredly too high. I won't claim anything for sure without a few weeks of driving my normal routine with it all stock. That way, I'll have a baseline to compare to when I start on the mods.

I'm a fuel mileage nerd, I know, but in 2008 I spent more than I ever have on diesel at 72,000 smackers. I'm on track to come close to that this year. 2009 and 2010 weren't as bad. Still, though, I make my living by tracking my cost per mile and keeping it as low as I possibly can. It's hard for me to leave that in the big truck at work sometimes.

[prerunner1982]

I understand..

Are you using E10 or Non Ethanol fuel? I recently started using Non Ethanol and think I may have gained 1-2mpgs. I was using E10 from 7-11 because it was about the cheapest gas around, but lately they have been upgrading some stores to have both E10 and Non Ethanol and it is not that much more expensive, maybe $0.06-$0.10 a gallon more.

Though I was able to get 20mpg consistently with E10, I am on track for 22-23mpgs. My last tank was 23mpg (391 miles and 17 gallons to fill).

And with the air being soo hot I can only hope that the cooler air in the fall will bring a bring a slightly better mpg as well.

[DeftwillP]

I wish we could get non ethanol 'round here.

[Mudderoy]

I wish we could get non ethanol 'round here.

I wish we could get ANY non-ethanol.

[Mudderoy]

I do not think this will cause a change in my mpg, but I have found an issue with a major portion of the fuel system. Namely the fuel pressure regulator/filter.

After testing the fuel pressure with the engine running I am seeing 49.5 which is correct, however with in 10 to 15 seconds of turning off the engine the fuel pressure drops to 0, or nearly so.

I believe this symptom points to a bad fuel pressure regulator and not a bad fuel pump. Since the fuel pressure regulator is about $70 to $100 and a complete fuel pump (that includes the regulator) is $205 and I'll have to drop the tank to replace either, I'm leaning to getting the entire pump. I have looking at the "Carter" pump. It isn't the cheapest, and it isn't the most expensive.

Thoughts and comments on what brand to go with are welcome! I'm not having a problem with the Jeep running, only starting on the first try, so I am not in a hurry to buy the pump. :drinking:

[prerunner1982]

I too have noticed my XJ taking a bit longer to start lately as well.

However, my understanding it that you don't have to drop the tank to remove the pump. I have not done it myself but have crawled underneath and it does seem that the pump can be removed with tank in place. The pump is on the front of the tank at least on my 93 it is.

[Mudderoy]

I too have noticed my XJ taking a bit longer to start lately as well.

However, my understanding it that you don't have to drop the tank to remove the pump. I have not done it myself but have crawled underneath and it does seem that the pump can be removed with tank in place. The pump is on the front of the tank at least on my 93 it is.

It may be possible, but I believe I read of some issues with the float. Getting it in correctly, bending it, or something. I'll have to do some re-research to confirm it. It's just my gut feeling that if you want to have trouble free install, you drop the tank.

[Paddletrucker]

I understand..

Are you using E10 or Non Ethanol fuel? I recently started using Non Ethanol and think I may have gained 1-2mpgs.

The places around me where I can get non-ethanol are a little too far out of my way and I haven't tried it.....yet.;)

I just filled up again today and showed 21.7mpg's. I'm thinking that's around where it's going to stay......UNTIL I do the lift and go to a larger tire.

I think I'll be happy with the fuel mileage even after the lift. Can't wait.

[Mudderoy]

The places around me where I can get non-ethanol are a little too far out of my way and I haven't tried it.....yet.;)

I just filled up again today and showed 21.7mpg's. I'm thinking that's around where it's going to stay......UNTIL I do the lift and go to a larger tire.

I think I'll be happy with the fuel mileage even after the lift. Can't wait.

I wish I had calculated my mpg before lifting. I have no idea what I was getting prior. :(

[jeepxj95]

84-96 u can do with out dropping the tank. 97-01 u have to drop the tank. the sender unit is on top. 84-96 it on the front side.

[Paddletrucker]

I'm loving this '95 XJ! I'm driving the crap out of it. I haven't even started my Dodge letdown(pickup) since I got the green machine XJ.

The fuel mileage has settled in at a few tenths over 23mpg's with me keeping it from 62-65 mph.

I'm thinking of getting a header for it and modifying the exhaust and see what it'll do.

Just couldn't be happier. Well, I guess I could. If all the stuff I wanna do to it was done already. Really NOT looking forward to wrestling the Dodge while the XJ is being personalized.

[Carves]

sorry guys but whats that in mpg? or a little converion plz

12liters / 100klm

2.64 imperial gallons / 62miles

3.17 U.S. gallons / 62miles

Im guessing the miles are the same US/Imp .... even tho you'se changed most everything else after turning Boston harbour into a giant teacup ... :D


I wish I had calculated my mpg before lifting. I have no idea what I was getting prior. :(

Having a baseline would certainly help.

Info from other vehicles is all well and good ... but they need to be in identical condition .... and driven in exactly the same way as yours ... for any real accuracy.

... and then you need to consider that the overall increased fuel consumption is caused by lotsa things .... some of which are only minor influences - on their own.

tyre tread patterns,
tyre sizes,
tyre air pressure,
extra rolling resistance of big wheels despite regearing for revs

.... and thats without getting into increased drag due to suspension lifts/roof baskets etc., ... and sensors that do what they want ... instead of what they should :D

Pay for Play .... is good terminology .... but getting the best mpg, for the circumstances can still be a good goal. ;)



Just to rub salt in the wound ..... :p

My average fuel economy is 12.5l / 100klm .... 18mpUSg .... in 2wd mode .... but its factory spec suspension/gearing and mainly highway ...

Ive had it up to about 22mpUSg with no junk up on the rack ...

Probably one of the most useless points of reference for economy is that erratic little dash gauge .... vehicle brand regardless ;) ... so I mostly ignore it and just check the tripmeter between fills.

Considering the XJ gets as good as ... and better than diesel 40 series toyos Ive had ... Im pretty happy with boxy little things economy running the big engine and all that drivetrain.


Nice job on logging all that data ... :thumbsup: ......... I was doing the same with coolant temps ... until the damned thumbdrive crashed and I lost it all :bang:

[Mudderoy]

Okay I have another riddle.

Recently I've been monitoring my OBD II scanning software while driving to and from work. The software shows instant mpg and average mpg. I routinely get between 16 and 19 mpg average over a 22 mile run back and forth. This is not highway but normal surface streets.

So my computer thinks I'm getting much higher gas mileage that I am. In reality I'm getting about 11.7 right now. :crazy:

[4.3LXJ]

Maybe the computer is not so smart. Don't know what to say about that. The one in my car isn't all that sharp either.

[Carves]

Maybe the computer is not so smart. Don't know what to say about that. The one in my car isn't all that sharp either.


heh heh ... I wonder how smart it is too sometimes .... I know the crank sensor is playing up ... even when it doesnt manage to spit up a code ... :D


Just wondering Mudderoy - since I havent bothered with using the scangauge for fuel monitoring ....

Isnt it very dependant on a lot of programming/resetting for the display to be accurate ??

... and how does it compare to the roof console display if you have one ??

[ike]

Let me throw my latest outing at ya…

Drove to Hot Springs Arkansas to the Super Lift off Road Park this past weekend.

On the interstate at 65 mph with a/c and wife, gear/supplies for a 5-day weekend I got a hand calculated 15.3 mpg.

On the way back we came thorough the mountains/back roads trying to maintain 60-65 mph I got a hand calculated 15.5 mpg with a/c.:comfort:

Counting 3 days of low speed off roading in 4 wheel drive low with the a/c most of the time and some city thrown in, the average for the trip came in at 11.3 mpg. :D

4:56 gears, lockers in each end, 12.5x35 BFG KM2 on the road aired up to 26psi, on the trail and in town for 3 days 12psi.

Total miles for the trip was 726.7 miles and my trip computer in the overhead showed an average of 15.1mpg on the hwy going and an average of 11.1 for the trip.
So mine reads very close.

And one other thing for those keeping up with the radiator issues.
I’ve still got the 180* thermostat in it and the single core aluminum/plastic radiator.
I’m seeing constant on road temps of less than 190* now that the temps are below 105*.

Three times out on the trail I turned the a/c off for a little while on some of the tougher sections, well just because it was getting close to 220* mark.

I had one instance where we had been on the trail for quite sometime running the a/c, then had to set and wait a while; (about 15 minutes) then turned engine off for about 4 minutes. When I did restart it engine was in heat soak and was about 240* when first started. I had a bad miss for just about 40 seconds until the temp dropped down to around 220*. Never had that happen before. :crazy:

All in all was a good road trip, did get a little rock rash on the right rear quarter and a tail light busted to go with it. ( kind a laid it on it’s side, slow flop :rolleye0012:) a little sanding, body hammer, very little bondo and a duplicolor rattle can, new tail light and it looks as good as new.

:watermelon:

[Mudderoy]

My wife was hearing a funny noise from the 99 so I drove it to work today. Man that thing is smooth as silk. Anyway I hooked up the OBD II scanner and monitored the same things as I have been monitoring on the 98

The avg MPG is worse! The instant MPG is better!

The upstream O2 sensor goes from .1 volts to .8 volts and stays at the .1 more often than the .8!!!

I really need to find out what the REAL mpg of the 99 is. I just need to get the wife to FILL up the tank instead of just putting $25 in it every few days. :S Oh and keep up with the mileage, gallons, etc...

The coolant temp took a long time to come up to temp. When it did it got up to 222 sitting in traffic but dropped to 208 after a mile of driving at 40+

From what I can tell it has the OEM radiator.

[TheWeiss]

I've read that using a low temp thermostat will decrease your mileage unless it is accompanied by adjustments to the computer. I can't remember whether it the lower temp makes the engine run richer or leaner but either way you might be hurting your mileage with the lower thermostat.

Can someone confirm and add some details?

[4.3LXJ]

Yes it can decrease milage. The lower temps will cause the ECM to run a rich mixture. But here is a thought for you. If you were to run a lower temp tstat, you can by pass the temp sensor with a resister on a switch (a Chevy trick) and use the lower temp stat with no loss in gas milage. I don't know how many ohms you need for that. I would have to figure it out with an ohm meter and a warm engine.

[ike]

Yes it can decrease milage. The lower temps will cause the ECM to run a rich mixture.

if the engine temp is above about 160* and the O2 sensors are heated up and reading properly, the ecm is in closed loop, it don't care if it has a 180* or 195* themostat, as long as it's in the operating range.

it will not richen the mixture to try and get the engine any warmer. it only does that to heat up the cats/engine on cold starts.

it will read the O2 content and make adjustments as needed to maintain an a/f mixture of 14.7.

if it has to run a little more fuel to make the a/f ratio of 14.7, it ain't much and it's sure not hurting my fuel mileage any more than anything else i've done.

it takes more fuel to push a lifted & loaded xj down the road.

the ecm only adds what you could call extra fuel when the engine is cold,(below 160*) once warmed up (in closed loop) it only adds/subtracts what's needed for the 14.7 a/f ratio which is always being adjusted due to all conditions.

if a coolant sensor is bad, it can add too much fuel, but if it's in the 185* to 200* range (as mine runs most of the time now) it does it's job and don't care.

for the lift , gears, tires and weight i've added to mine, i think 15+ mpg hwy is good.

considering what i put it through on the trails for 3 days, a 5 day round trip average of 11.3 for 726.7 miles ain't that bad either.

add to all the above...it didn't get any better fuel mileage while running a 195* thermostat! :smiley-talk024:

[Carves]

Looks like your MPG thread is becoming a general tech thread Mudderoy .... ;)


I've read that using a low temp thermostat will decrease your mileage unless it is accompanied by adjustments to the computer. I can't remember whether it the lower temp makes the engine run richer or leaner but either way you might be hurting your mileage with the lower thermostat.

Can someone confirm and add some details?


Whilst an approx 200* running temp may provide optimum fuel efficiency .... the reality seems to be - that coolant temps of down to 185* cause negligible increases in fuel consumption ....

In 12yrs of owning a new TJ and two used XJs .... Ive only ever experienced any noticeable, increased, fuel consumption - due to running temps of less than 180* .... same as occurs with most vehicles ....

Dodgy sensors, lifts kits, big wheels, incorrect tyre pressures and lotsa junk on the roof rack cause worse than a 180* t'stat.

Its not the thermostat temp rating thats relevant ... Its the coolant temp that the CTS sends to the PCM.

OBDI XJ parts books even list a 180* thermostat as an optional part .. :eek: .. :D

From the OBDII FSM ...

MilCode 17 / PO125 ... Engine too cold.

Closed Loop Temp Not Reached / Engine does not reach 20*F within 5 minutes with a vehicle speed signal.

Now I dunno for sure ... but on an OBDI ... MilCode 17 may also refer to the fact that the PCM isnt registering the 160* coolant temp defined as a "warmed temp" for trip definition purposes.

170* on 99+ models according to a FSM I glanced thru.

Additionally .... Closed Loop Temp Not Reached may even refer to the fact that the O2 sensor heaters are faulty and not reaching the 600*f needed to work properly ;) .... but I'd think in reality - its a coolant temp between 20* & 65* and a timer function.

2yrs of watching the scangauge for a coupla minutes after startup .... and Closed Loop has always occurred at about the same time .... After a coupla minutes and when the CTS/PCM registered a 65* coolant temp.

Understanding that the system isnt always in Closed Loop, despite the running temp, adds a different perspective too ... and confirms the need for 100% operating TPS, MAF/MAP, CTS, O2s etc

- Ignition switch ON ............. Open Loop
- Engine start-up (crank) ...... Open Loop
- Engine warm-up ................ Open Loop
- Idle ....... at operating temp .................... Closed Loop
- Cruise .....at operating temp .................... Closed Loop
- Acceleration ..................... Open Loop
- Deceleration ..................... Open Loop
- Wide open throttle (WOT) ... Open Loop
- Ignition switch OFF ............ Open Loop


Modern Junk :mad: .... and to think I used to hate Holley carbies with a passion .... :D

[jeepxj95]

figure this out my 95 ran at 210 all the time. then the clutch fan started to go. so i flushed it and it ran 185-210. depending if in traffic or going 60 mph. so i put the zj clutch fan and it runs 185 all the time unless im playing on trails or having a little fun i might see 210. ive ran 180 t stat and got the same mpg winters were a little cold lol. so when that died 3 months later i put the 195 back in and got the same mpg as the 180. so after the clutch fan and the flush im running at about 185-195 with the 195 thermo unless its a cold morning 40's so far. it runs 180. my ? is how can a 195 thermo hold 185 most of the time? sorry so long

[Carves]

figure this out my 95 ran at 210 all the time. then the clutch fan started to go. so i flushed it and it ran 185-210. depending if in traffic or going 60 mph. so i put the zj clutch fan and it runs 185 all the time unless im playing on trails or having a little fun i might see 210. ive ran 180 t stat and got the same mpg winters were a little cold lol. so when that died 3 months later i put the 195 back in and got the same mpg as the 180. so after the clutch fan and the flush im running at about 185-195 with the 195 thermo unless its a cold morning 40's so far. it runs 180. my ? is how can a 195 thermo hold 185 most of the time? sorry so long


Coupla possibilities ...

- The CTS is out a bit, giving low temp readings.
- The 195 t'stat could be a hiflow,
- Too many, extra, holes drilled in it instead of just one, 1/8th breather hole,
- It opens earlier than designed .... One I've got is an early opener ... they're not the most exact or accurate, pinnacles of human engineering ... despite the wonderous claims by manufacturers .. ;) .. :)

Typically ... a running temp will be about 10* above a t'stat rating .... in a good cooling system .... but we are talking XJs here ... :D


Sorry Mudderoy ..... deviated a bit from your petrol consumption .... :o

[4.3LXJ]

Typically ... a running temp will be about 10* above a t'stat rating .... in a good cooling system .... but we are talking XJs here ... :D


Sorry Mudderoy ..... deviated a bit from your petrol consumption .... :o

That might be for Jeeps, which in my opinion have a marginal cooling system. I have a 195° stat in mine which has a Chevy in it and that is where it runs. If it is able to cool in all situations, under power etc it will maintain the temp of the stat.

[jeepxj95]

Coupla possibilities ...

- The CTS is out a bit, giving low temp readings.
- The 195 t'stat could be a hiflow,
- Too many, extra, holes drilled in it instead of just one, 1/8th breather hole,
- It opens earlier than designed .... One I've got is an early opener ... they're not the most exact or accurate, pinnacles of human engineering ... despite the wonderous claims by manufacturers .. ;) .. :)

Typically ... a running temp will be about 10* above a t'stat rating .... in a good cooling system .... but we are talking XJs here ... :D


Sorry Mudderoy ..... deviated a bit from your petrol consumption .... :o

nope cheapest thermo i could find. one pin hole. anyone else? collage starts the 22nd and its engine performance YES about time a fun class. and ill ask my teacher. oh that reminds me still need to put coolant in the xj be4 it freezes

[Mudderoy]

heh heh ... I wonder how smart it is too sometimes .... I know the crank sensor is playing up ... even when it doesnt manage to spit up a code ... :D


Just wondering Mudderoy - since I havent bothered with using the scangauge for fuel monitoring ....

Isnt it very dependant on a lot of programming/resetting for the display to be accurate ??

... and how does it compare to the roof console display if you have one ??

I don't know, and no, I have no other device that gives me this information :(

[jeepxj95]

figure this out my 95 ran at 210 all the time. then the clutch fan started to go. so i flushed it and it ran 185-210. depending if in traffic or going 60 mph. so i put the zj clutch fan and it runs 185 all the time unless im playing on trails or having a little fun i might see 210. ive ran 180 t stat and got the same mpg winters were a little cold lol. so when that died 3 months later i put the 195 back in and got the same mpg as the 180. so after the clutch fan and the flush im running at about 185-195 with the 195 thermo unless its a cold morning 40's so far. it runs 180. my ? is how can a 195 thermo hold 185 most of the time? sorry so long

oh and all temps without a fan shoud.

[bobalou]

Interestingly, the last post in this thread was 9/10/11. The next day, 9/11/11, my Jeep was stolen. I had just gotten back from Burning Man the week before. Needed a new steering column, small, rear seat window, and minor fender work. The police spotted it four days after it was stolen, so it wasn't gone that long.

After I refilled the tank, it had only gotten 9mpg on the one tank. Wonder if they siphoned out some gas. Since then, I've only been one one road trip - to Death Valley - and haven't seen any mechanical problems from the theft. Gas mileage is about where it was before.

[Firemanray]

Interesting this thread pops up today. I was looking at my expenses for the first quarter, a THOUSAND dollars per month in fuel!!! That's just dumb!

[Mudderoy]

Interesting this thread pops up today. I was looking at my expenses for the first quarter, a THOUSAND dollars per month in fuel!!! That's just dumb!

Obviously this is due to the millionaires not paying their fair share! :smiley-whacky119:

[89Laredo]

Stock renix was getting 16mpg in winter, with the warmer weather I am getting 18. Last tank was 18.83 IIRC.
I have 710 (ford 19lb) injectors, no ballast resistor, and am running 5w40 synthetic. I also have a Large whistling vacuum leak I am unable to find, Suspect the intake gasket :(
I am also thinking my cat is a little restricted and will be buying a 2.5" system at some point this summer, and a small miss at idle in Park (does not miss in Drive).
I have a TC lockup switch and try to lock it at 35mph. This keeps me at 1050rpm at 35mph.
I switched the thermostat for a 180* about two weeks ago when it was 86* out, engine was running ~215 at a stop with the 195, the temperature has dropped again and it runs pretty cool, but seems to have a pretty big swing between 210 and 180.
I am going to see if my MPG has decreased with the new thermostat, but am at 1/2 tank right now so I probably wont fill for another week unless I decide to go on a big trip.
Kind of a crappy video, but you can see the RPM drop at 35 when I lock the TC, and the temperature swing on a 50* (IIRC) day.
Random Jeep Stuff 3/31/12 - YouTube

[Mudderoy]

Stock renix was getting 16mpg in winter, with the warmer weather I am getting 18. Last tank was 18.83 IIRC.
I have 710 (ford 19lb) injectors, no ballast resistor, and am running 5w40 synthetic. I also have a Large whistling vacuum leak I am unable to find, Suspect the intake gasket :(
I am also thinking my cat is a little restricted and will be buying a 2.5" system at some point this summer, and a small miss at idle in Park (does not miss in Drive).
I have a TC lockup switch and try to lock it at 35mph. This keeps me at 1050rpm at 35mph.
I switched the thermostat for a 180* about two weeks ago when it was 86* out, engine was running ~215 at a stop with the 195, the temperature has dropped again and it runs pretty cool, but seems to have a pretty big swing between 210 and 180.
I am going to see if my MPG has decreased with the new thermostat, but am at 1/2 tank right now so I probably wont fill for another week unless I decide to go on a big trip.
Kind of a crappy video, but you can see the RPM drop at 35 when I lock the TC, and the temperature swing on a 50* (IIRC) day.
Random Jeep Stuff 3/31/12 - YouTube (http://www.youtube.com/watch?v=WJlk0OmROtE)

Wow and at 240k miles too. So I don't know metric tire sizes, are the tires you are running a larger diameter than stock? If so how are you compensating for you mpg calculations?

[89Laredo]

Theyre about 1.25" bigger than stock, 235/75/15s are what most people on stock height run.
No Compensation.

[olds-cool]

I'm running 235/75 all seasons (street tread) on mine right now with a 3" lift. No other major weight adders other than a box with 2 12's in it (figure about 50lbs). I installed an overhead console a few days ago and so far I am averaging between 16-16.5mpg. I figure I'll let it go for a week or 2 to get a real average but it's a lot better than I thought I was getting.

[Mudderoy]

Theyre about 1.25" bigger than stock, 235/75/15s are what most people on stock height run.
No Compensation.

So that means your mileage is going to be higher, which means your mpg will be less. Assuming you are using the odometer to calculate your mpg.

[Mudderoy]

I'm running 235/75 all seasons (street tread) on mine right now with a 3" lift. No other major weight adders other than a box with 2 12's in it (figure about 50lbs). I installed an overhead console a few days ago and so far I am averaging between 16-16.5mpg. I figure I'll let it go for a week or 2 to get a real average but it's a lot better than I thought I was getting.

As you guys calculate your mpg please remember you can record it in the UserCP area.

Is that 16 mpg city or highway (mix?)

[prcjeep]

you said you can track this... Where? i see where i can type in what i get but as far as tracking... I dont see it

[Mudderoy]

you said you can track this... Where? i see where i can type in what i get but as far as tracking... I dont see it

Who said track? Are you talking to me? If so UserCP > Edit Your Details :link: (http://www.xjtalk.com/profile.php?do=editprofile)

[prcjeep]

Who said track? Are you talking to me? If so UserCP > Edit Your Details :link: (http://www.xjtalk.com/profile.php?do=editprofile)

opps... yes i was talking to you, it says record, not track:sign0181: would be cool to have a tracking ability built in though

[Mudderoy]

opps... yes i was talking to you, it says record, not track:sign0181: would be cool to have a tracking ability built in though

It would. :D

[89Laredo]

If I remember Ill use my GPS to/from work tomorrow and see how far off my gauge actually is.

[Mudderoy]

If I remember Ill use my GPS to/from work tomorrow and see how far off my gauge actually is.

I'm not sure if the same thing will work on a pre 97 XJ, but I was able to correct my speedometer and odometer with a $30 gear that goes in the transfer case. Might be nice not only for accurate mpg calc, but just knowing the right speed while driving around.

[89Laredo]

I really dont think 1.25" of tire size makes a big enough difference to buy a new speedometer gear. Only time I will do that is after I go to bigger tires and different gears.
IIRC my speedometer is about 2mph off at 55, but I will run with the GPS if I remember, its about 18mi each way to work.

[Mudderoy]

I really dont think 1.25" of tire size makes a big enough difference to buy a new speedometer gear. Only time I will do that is after I go to bigger tires and different gears.
IIRC my speedometer is about 2mph off at 55, but I will run with the GPS if I remember, its about 18mi each way to work.

Ahhh ok. Well I guess I've never just upped my tires by so little. Having the speedo read wrong drives me nuts. Yeah 2 mph isn't too bad. I just like knowing my real speed when I see a cop. :rolleye0012:

[olds-cool]

Muddy, that's 16 with about a 70/30 split of highway/in town driving. I actually managed to push the average up to 16.9 this morning all on secondary roads. Again, I think I need to give it a week or 2 to really average out. It's still at the point where I can coast down a hill and watch it go up .1. Of course, now that I have the console, I'm having an internal contest with myself to see how high I can get it vs keeping my foot out of the skinny pedal.

[Mudderoy]

Muddy, that's 16 with about a 70/30 split of highway/in town driving. I actually managed to push the average up to 16.9 this morning all on secondary roads. Again, I think I need to give it a week or 2 to really average out. It's still at the point where I can coast down a hill and watch it go up .1. Of course, now that I have the console, I'm having an internal contest with myself to see how high I can get it vs keeping my foot out of the skinny pedal.

lol yeah maybe during the break in period of the new engine I'll be able to take it easy and see some good mpg figures. Prob not since the engine will be so tight at first.

[89Laredo]

So that means your mileage is going to be higher, which means your mpg will be less. Assuming you are using the odometer to calculate your mpg.
I always thought it was the other way around...
Bigger tires=more mileage traveled than odometer indicated, same amount of fuel used=Higher mpg than indicated.

Looks like my speedometer is about 2.5% off but Im gonna do some more driving and see. 55mph was the highest indicated speed on the speedometer. I measured 11.4miles with the odometer.

http://farm8.staticflickr.com/7181/7041215675_be8f4480be_b.jpg

[Mudderoy]

I always thought it was the other way around...
Bigger tires=more mileage traveled than odometer indicated, same amount of fuel used=Higher mpg than indicated.

Looks like my speedometer is about 2.5% off but Im gonna do some more driving and see. 55mph was the highest indicated speed on the speedometer. I measured 11.4miles with the odometer.

http://farm8.staticflickr.com/7181/7041215675_be8f4480be_b.jpg

You may be correct. I get left and right mixed up as well! :out: