Northwoods Snowman

OK, so I've been reading a lot about people who suddenly have horrible gas milage (myself included) when they used to get better and can't figure out why. I'm wondering how much of an effect having 10% ethanol in gas plays. Feel free to chime in if you're noticed a chage between 10% ethanol gas and "pure" gas, or if you haven't noticed.

If you could too, state the following for comparison:

1. Gas used (grade and ethanol content)
2. Jeep setup (stock or built; list lift/tires/gears)
3. Mileage (state city/highway mix, and for consistency use US gallons)



In my case I bought my jeep in the middle of November and when I drove it home, I got 23mpg going 60, 20.5 or 21 going 70, and about 15.X mpg around town. I haven't gotten that since. I did put new tires on (LT225/75-16) instead of passenger tires, but I don't think that would account for the milage dropping to 10-11 mpg city, even with it getting a little colder (40's down to teens). What I would like to do (and I think it would be great if other people would do the same) is run a couple tanks with 10% ethanol gas, and a couple tanks with pure gas and see if there's any substantial difference.

I'm going to have to put this off for a couple tanks though as I also found out I had a bad head gasket which I just replaced. I don't know if the gasket was blown when I bought it, or if it blew when the mileage dropped, so I'm going to have to put some miles on it and see how it's doing now that it has a clean bill of health. I've only put about 15 miles on it since the head work so I can't draw any conclusions, but my read out on my console is saying I've been getting less than 13 mpg so time will tell. I'm also going to try and do a little extened highway driving before starting the "test" so I have a good basline and know how much difference, if any, the head gasket made.

My stats before the engine tear down were:

1. 87, 10%
2. Stock
3. 11 city avg.

Northwoods Snowman

Oh, FWIW, I found the site pure-gas.org to be a good place to find gas stations w/o ethanol.

djb383

Recent changes/drops in gas mileage are mainly due to winter blend gasoline vs summer blend gas, not to mention winter vs summer driving conditions. Most all gasoline now days contains ethanol, year round.

EUGENE the JEEP

yes it stinks, an cost too much too

OttawaXJ

Ethanol makes the gas cheaper but yes it is too much here.. Down there in the US I'd probably drive around a jeep nonstop just because I could with low prices.

EUGENE the JEEP

yes thats rite, spend spend spend.

OttawaXJ

Theres a few things that in envy about americans, and one of the few is the gas prices. lol

mrfajita

Ethanol is definitely detrimental to mileage, along with winter blend vs summer blend. On summer gas with no ethanol I got 21mpg on a few tanks, the best I have gotten on E10 winter is 16.5.

off topic, 242nd post!

Northwoods Snowman

I know there are more factors like summer/winter blend, but I'm curious as to how much of a difference the ethanol makes for our 4.0L engines. I'm hearing people talking about getting 16 or more city with 31-33 tires and I'm getting less than 12 with a stock setup, babying the throttle too. Granted it would also be cool to see if there was a correlation between the mileage and if you're in a Northern or Southern climate.

I'm just having a hard time believing my new tires and colder weather/gas blend drops my mileage by 25-30%. Granted, I don't know that my drive home with the Jeep was on non-ethanol gas It got decent mileage around town back in Nov, and now it sucks, but I don't know what changed. I've read reports of people claiming the switch to E10 cut their mileage 20-30%, so I'm curious how much of an effect it has on our engines.

I'm wanting my 40 mpg city motorcycle back! Stupid snow and salt.

Well, if nothing else, I'll find out if it's the weather in like 5 months.

djb383

16 mpg city on 31-33..............BS.

Northwoods Snowman

Your guess is as good as mine. Either way, there are people getting better mileage than I am with rigs that should not be getting better mileage than I am.

djb383

There's just too many variables regarding/effecting mpg. Just make sure the XJ has a good tune and go easy on the push pedal. Install a vacuum gauge, keep the needle between 15-20, you'll get better mileage but your best mileage is most likely achieved during summer/warmer months.

I still say, BS on 16 mpg CITY, running 31-33 tires. Maybe that's calculated after installing one of those ebay "chips".

http://www.google.com/products/catal...ed=0CCUQ8gIwAA#

billfrank85

I get 35 MPG with my fuel atomizer, tornado air intake thing, and my fuel line magnets.

I was hoping to install a vacuum gauge in my XJ...which line would you suggest splicing it into?

tjwalker

I did quite a bit of research of the affect of 10% ethanol on gas mileage.

The best "study" that I found was an independent one (no ethanol money) conducted at the University of Iowa a few years ago.

It used a half a dozen different types of vehicles for an extended period, and the study seemed sound.

On AVERAGE, 10% ethanol caused a 4.3% decrease in gas mileage.

mrfajita

On my 4.0 there is a vacuum port on the manifold that is just capped, not connected to anything, at the front of the manifold. That's where I'd put one.