mikeg216

I have had an xj and other 4x4 vehicles and trucks that have weighed nearly double the zj. Now don't get me wrong, I love her and understand the jeep appeal, but 12mpg in mixed driving is atrocious! I have a motor home more then rwice the size with a 454 that gets the same mpg!

North_Coast_ZJ

I get about 14 in the city with the 4.0L, so your milage doesn't sound that far off at least around town.

dave1123

Are you trusting the VDC or are you actually checking the mileage manually?

I had a Chevy 3/4 ton 4X4 that was giving me 8 mpg.

dnuccio

ive heard that the overhead AKA lie-o-meter actually reads high most of the time

mikeg216

I'm making my own calculations as to the mileage, I never trust the display. I know you don't buy a jeep for the mpg but sheesh I've spent less on gas with a 350 extended length van with work bins and a full load of tools and gear!

TNUCKL

Just my first zj in November. Definately expected better than the 14.5 combined I'm getting with the 4.0 I6. Its slow and a hog on gas. Not sure I'm keeping it. My previous ride was a Yukon with a 5.3 and I got the same mileage. Hopefully it will get better mileage once spring and summer come around.

mr.clean

I have a 94 ZJ with 4.0 with 31" tires and factory 3.73 gears, so my mileage is off, and I have a after market muffler and cat.. But I cal. to be getting 15.5 mpg., but with my factory size tires I was getting 19.2 mpg. I can't say that my Jeep is slow or that it gets bad gas mpg. But I do change my plugs and wires as I should and keep a check on them. I also, make sure that my throttle body and intake are clean often. I run a lot of cleaner in my fuel to clean my injectors and after that I have run Marvel Mystery Oil in my gas. I put 4oz. to every 10gal. of gas. Also, just a side note, if the gas you are using is ethanol it lowers you mpg.. If you can find gas that is ethanol free and run it you will get better mpg.. I have done this myself just to check cause I was told that you would. Running ethanol free gas to check your mpg.. You need to run 2 tanks and check the 2nd one. The 1st one will still have ethanol in it and your computer has to adj. to not having ethanol. My Jeep run a lot better with ethanol free gas as of it started quicker, run smoother, and felt like it had more power.

mikeg216

There is no such thing as ethanol free gas in ohio. You are wasting a ton of money with all those additives all the time, once per oil change will suffice. The 4.0 is as reliable and simple as an anvil, you are over doing it.

mr.clean

What I meant to say was that I ran a lot of cleaner to make sure my injectors were clean right after I bought it and after that I started just using Marvel Mystery Oil in my gas. You only put 4ozs to every 10gals of fuel. A ton of money, I don't think so. The injector cleaner I used was only a $1 a bottle and the Marvel Mystery Oil is like $2.50 for a 32oz bottle and carb. cleaner to clean throttle body is like $1.50 a can. If you add all that up, the money I am saving because of my good mpg, it all than pays for its self. And there is ethanol free gas in Ohio. You just have to look for them. There is 32 stations that sell it. http://pure-gas.org/index.jsp?stateprov=OH There is the site to show you where they are.

mr.clean

Also, if your Jeep has the setting to show your mpg at that moment put it on it and keep an eye on it. I do this and it keeps me from having such a heavy foot all the time. If you have not looked at your throttle body to see how dirty it is, I would check it. The dirtier it is the more restrictive it is. That will hurt your performance and your mpg cause you will have to open it up more to get the air to it and the tps will tale the cpu to spray more fuel causing lower mpg.. I would put a high flow air intake on it. You can find them kind of cheap on e-bay. Also, a better flowing exhaust system will give you better mpg.. Look under at your exhaust after your muffler where it goes over the rear-end and back down. It has been compressed to pass by the track bar and the gas tank heat shield. A no cost help, if your laws will let you, is to cut off the tale pipe and turn it down or out to the side. This will help performance and mpg some. Did this with a friend to his 95 v8 GC after he showed it to me and wanted it done. It had a Flowmaster with the stock tail pipe still. It, also sounded a lot better after we cut the tail pipe off. If you have to have a tail pipe there are companies that sale bigger tail pipe cat back systems what are not made that way. Like 4Wheel Drive Hardware for one. 2.5" kit #cre1022030 and 3" kit #cre1022040. If I was going to do that I would change out my cat. also to a better flowing one.

mr.clean

One my thing that can cause your mpg to be low is your 02 sensor. They will not last forever. If you have over 120,000 miles on it and it has not been changed, that you know of, it may need to be changed. And, I know you don't have any codes saying that it is bad, but that does not mean that it is not what could be causing your mpg to be lower than they should be. I was told when I worked at a Jeep dealership that it was a thing to change when you did a full tune up.

mikeg216

those 32 stations are selling gas for boats and or avgas with lead,its at least double the price of regular gas if not more, i clean the throttle body as well every oil change . the mystery oil...i dunno really i dont have any experience with it, i stick to lucas and seafoam myself. if you havent check out the bob is the oil guy forums.

dave1123

Many, many, many moons ago, guys used to drag race with 100% alcohol fuel. They got lots of power but the fuel usage was incredible! Alcohol doesn't have the latent heat energy content per gallon that gasoline does. The EPA mandated 10% alcohol content in today's fuels to try to save gasoline imports. It actually INCREASED gasoline usage because of the power produced.

When I was in the Navy, we stole 115/145 av gas for our rides. This was the closest thing to nitrous you could get, but tore up motors because of not having any lubricity in the fuel. We'd put 8 ozs of 10 weight oil in 20 gals of fuel to help this.

Summing all this up, straight gasoline will give you much better power and performance and better mpg than E10. Problem is, where do you LEGALLY get it? I once found a station in Tupper Lake, NY where you could get 85 octane leaded gasoline. I asked how they could get away with selling it and was told many people use it the old snow removal eguipment that still used carburators. How that makes it legal, I have no idea.

mr.clean

Whatever! You are smart, I am dumb, I know nothing about cars, and you know it all. That is why I don't come on here much. I was an ASE mechanic in a Jeep dealership along with my father. I left there and went to work for DANA making steering knuckles for Jeep and Ford. I have been working on cars for around 30 years and my father for over 55 years which is still an ASE mechanic. I have forgot more about Jeeps than most people on here will ever know. I was taking Jeeps apart that had only 5,000 miles on them. And as far as drag racing, I do that also. I run a 69 Plymouth Roadrunner with a built 500 cubic inch 850 HP motor and a 72 Plymouth Valiant Scamp with a 366 cubic inch 445 HP motor. As far as your many moons ago, some people still use 100% alcohol fuel. Have you not heard of alcohol funny cars? And I don't think I would be boosting that when I was in the Navy that I stole anything more less gas. I also never said anything about running Leaded fuel. I said ethanol free gas which does not have lead in it. It is against the law to sale leaded fuel for street use. Yes, some people still do it. My Roadrunner has 120 leaded in it, but I don't drive it on the street. My Scamp will run off regular gas, but if I put E10 in it I have to use Marvel Mystery Oil so it does not hurt it. Straight up gas does not have lead in it and can be bought LEGALLY. It is called ethanol free gas. Just go to the site that I put in one of my other messages and look up your state. It is that easy. Oh, sorry I am STUPID, forgot that for a moment there. Oh, and all the stations in the list for Ohio are not selling gas just for boats or that have lead it. Some are, but not all of them. If E10 is so good, why is it not used at the airports in planes? They are not allowed to put it in them at all. Look it up for yourself. Learn more about ethanol gas and what it does to older cars for yourself. Don't believe me, because I don't know what I am talking about. Here is a little for you and you can check the References for yourself.


E10, a fuel mixture of 10% anhydrous ethanol and 90% gasolinesometimes called gasohol, can be used in the internal combustion engines of most modern automobiles and light-dutyvehicles without need for any modification on the engine or fuel system.E10 blends are typically rated as 2 to 3 octane higher than regular gasolineand are approved for use in all new U.S. automobiles, and are mandated in someareas for emissions and other reasons.[1]The E10 blend and lower ethanol content mixtures have been used in severalcountries, and its use has been primarily driven by the several world energycrises that have taken place since the 1973oil crisis.

Other commonblends include E5 and E7. These concentrations are generally safe for recentengines that run on pure gasoline. As of 2006, mandates for blending bioethanol into vehicle fuels had beenenacted in at least 36 states/provinces and 17 countries at the national level,with most mandates requiring a blend of 10 to 15% ethanol with gasoline.[2]

One way tomeasure alternative fuels in the U.S. is the "gasoline-equivalent gallons" (GEG). In 2002, the U.S. used asfuel an amount of ethanol equal to 137,000 terajoules (TJ), theenergy equivalent of 1.13 billion gallons (4.3 billion liters) of gasoline. This was less than 1% of the total fuel used that year.[3]

E10 and otherblends of ethanol are considered to be useful in decreasing U.S. dependence onforeign oil, and can reduce carbonmonoxide (CO) emissions by 20 to 30% under the right conditions.[4]Although E10 does decrease emissions of CO and greenhouse gases such as CO2 by anestimated 2% over regular gasoline, it can cause increases in evaporativeemissions and some pollutants depending on factors such as the age of thevehicle and weather conditions.[5]According to the Philippine Department of Energy, the use of not more than a10% ethanol-gasoline mixture is not harmful to cars' fuel systems.[6]Generally, automobile gasoline containing alcohol (ethanol or methanol) is not allowed to be used in U.S. certificated aircraft.[7]

Disadvantages to engines

The use of ethanol blends in conventional gasoline vehicles is restricted to low mixtures,as ethanol is corrosive and can degrade some of the materials in the engine andfuel system. Also, the engine has to be adjusted for a higher compressionratio as compared to a pure gasoline engine to take advantage of ethanol'shigher oxygen content, thus allowing an improvement in fuel efficiency and areduction of tailpipe emissions.[8] This information is based on the modifications made by the Brazilian automotive industry at the beginning of the ethanol program in that country in the late 1970s, and reflects the experience of Volkswagen do Brasil.[8]

Other disadvantages

Disadvantages to ethanol fuel blends when used in engines designed exclusively for gasoline include lowered fuel mileage, metal corrosion, deterioration of plastic and rubber fuel system components, clogged fuel systems, fuel injectors, and carburetors, delamination of composite fuel tanks, varnish buildup on engine parts, damaged or destroyed internal engine components, water absorption, fuel phase separation, and shortened fuel storage life.[9][10][11] Many major auto, marine,motorcycle, lawn equipment, generator, and other internal combustion engine manufacturers have issued warnings and precautions about the use of ethanol-blended gasolines of any type in their engines,[12]and the Federal Aviation Administration and major aviation engine manufacturers have prohibited the use of automotive gasoline blended with ethanol in light aircraft due to safety issues from fuel system and engine damage.[9][10][11][13]

References

1. ^ E10: Everyvehicle's ethanol blend, drivingethanol.org.[dead link]

2. ^ ab"TowardsSustainable Production and Use of Resources: Assessing Biofuels". United Nations EnvironmentProgramme See Table 3.3. 2009-10-16. http://www.unep.fr/scp/rpanel/pdf/Assessing_Biofuels_Full_Report.pdf.Retrieved 2009-10-27.

3. ^ [1]

4. ^ Low-Level Ethanol FuelBlends, Clean Cities fact sheet, April 2005.

5. ^ E10Emissions, U.S. Department of Energy.

6. ^ "AF/Bioethanol.htm Bioethanol".Doe.gov.ph. http://www.doe.gov.ph.Retrieved 2010-12-05.

7. ^ SpecialAirworthiness Information Bulletin CE-07-06 (October 27, 2006), Federal AviationAdministration

8. ^ abcd "Sustainablebiofuels: prospects and challenges". The Royal Society. January 2008. http://royalsociety.org/Sustainable-biofuels-prospects-and-challenges/. Retrieved 2010-12-08. Policy Document 01/08, Figure 4.3

9. ^ abcIs fuel with an increased level of ethanol a problem for small gas engines?,Tools & Power Equipment, Consumer Reports, 24 June 2009

10. ^ abVatalaro, Michael,ASerious Problem - A Corny Solution, Boat US Magazine, (July 2006)

11. ^ abMaloney, William,EthanolPros & Cons in Automotive Gas, retrieved 8 August 2011

12. ^"ManufacturerE10 (Ethanol) Fuel Recommendations". Fuel Testers. http://www.fuel-testers.com/manufacturer_fuel_recommendations_ethanol_e10.html.Retrieved 6 August 2012.

13. ^ FAA to STC Holders: NoEthanol in Auto Fuel, EAA, retrieved 8 August 2011

mikeg216

Look, I understand what ethanol is. It's a government hand out to agribusiness and has no business in my gas tank as it has less energy density then 100% gasoline. My owners manual for my 88 xj goes so far as to state that it must not be used in the 4.0 at all.

As far as Marvel Mystery Oil, its 75% mineral oil 24% turpentine and 1% animal fat. I'm sure it provides some sort of lubricity but as far as increased mpg in a fuel injected car, no.

The cost of using 100% gas or anything else then pump gas far outweighs the benefits period.

I'm not sure how using mystery Oil helps on your high octane drag cars... Any damage done because of using these gasolines should be more then overcome using the right synthetic oils with the correct additives such as zddp which is necessary for any motor with flat tappet camshafts or solid lifters, such as the 4.0 modern oils do not normally contain zddp so it must be added, I use Lucas Oil break in additive to provide the zinc the engine requires while still taking advantage of the upsides synthetic oils provide.