Miles driven divided by how many gallons you put in.

So for example mine: 166.4 / 16.79 = about 9.9/10 mpg

 

i know that, just talking about with bigger tires since your odo will be off with them. just say for example speedo with 33s says 60mph but in reality you going 65mph. how do you figure the miles per tank that way

 

Uhhhh......ehhhhhh........ummmmm.....I dunno :| Last time I checked, i don't go any faster than normal sized tires. But I don't know this stuff haha

 

find a suitable road, find a mile marker and zero your odometer. drive some distance down the road to another marker( I'd go at least 10-20 miles)
Then check your odometer reading with the mile marker distance.....
Calculate the difference in %, then multiply your odometer reading to get true miles travelled...........10mpg seems horrible!
Even if I drove around like a jackass all the time, I don't think I'd get 10mpg.....

 

Seems a little complicated haha.....gonna have to find time to do that. Either way, I know that something is up because I'm not crazy driver. I go the speed limit and don't floor it very often and don't stop on a dime. I know it isn't my driving so we shall see what happens Sunday o.o

 

sounds like a lot of work to find out, was hoping for easy way or someone else to figure it out. but after this next tank of gas ill try it out (next week sometime)

yeah 10mpg does sound pretty bad. i remember the good old days while stock and got over 400 per tank

 

You can buy a speedo gear if you don't ever want to change tire sizes or gears in your diff.

 

So had to go out to my sisters tonight to watch her dog for the night (other emergency happened with my nephew) and comparing my odo to the mile markers and for every 10/10 for miles in a normal vehicle my jeep gets a little less than 9/10 if that makes sense

Hope that can help you out and I'm running 33s with 3.07 gears

I think I need go add 1/10 a mile I drive to whatever my tank says. Correct? Or no?

 

So let me get this right, you know your o2 is bad, and your gonna replace the spark plugs?....holy crap that hurt my brain!!!


Bad o2 sensors will cause a huge decrease in milage. Spark plugs.....not so much, unless they are completly burnt and you have misfires.

I would start with the o2 sensors first. They are supposed to be changed out regularly and im sure yours have prob never been replaced.(and you know one is bad!)



Oh yeah, one more thing........Ur buddy CANNOT time a 4.0L. The timing is not adjustable on a 4.0L. There is a sticker under the hood that will tell you this.

 

Going off of tenths of a mile wont get you a very accurate calculation.......I would get on the freeway, and drive about 10 miles out at least, and mark the miles..........you'll get a more accurate calculation.
At 9/10 for every 10/10 you would be 10% off.

 

Well I have had people on this forum, not this thread tell me that I don't really need to replace the o2 censor after the cat. I was going to but ended up taking it back cuz I could not get it out to save my life. Did everything short of heating it up with a map torch.
My jeep was very abused before I bought it, if you saw it in person you could tell :/

 

The one after the cat doesn't have much effect on mileage, it just measures the efficiency of the cat. The one before the cat is the one that will rape your mileage. If its got over 120k on it, you should replace it whether there is a code for it or not.

 

That's all I needed to know its got 128k on it. I guess I'll see what I can do about that

 

Anyone have a grey drivers seat and base?? I have badddd death lean I have a thread in wanted

 

What year jeep?...i may have a 97-01 sitting around.