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Who has over 17 mpg w4.0L???

8K views 92 replies 73 participants last post by  Gritz 
#1 ·
I was wondering who gets better then 17mpg in there Wrangler TJ? What Mods are done to you Jeep and what gas mileage are you getting.

Thanks
Mike
 
#53 ·
Well after reading all of these I have decided my 2.5 really sucks. My jeep is bone stock with 235 tires on it which I think are about 28 or 29". It is a 98 with 5spd. I get about 190 miles per tank and my mileage is right around 17-18. I have seen 19 maybe once. I'm rebuilding my 4.0 drive train to drop in it this year and hope not to loose to much on the MPG.

I wonder if some of the difference we are seeing in mpg is because people are running around with a speedo that is out of cal. I have checked mine with my GPS many times and it is within 1 mph at 65. By the way I comute 12 miles each way on the freeway with no traffic going about 70.

So put me in the 17-18 range.

Brandon
 
#54 ·
I just got 19 mpg and its not all highway.... mst of it is NOT highway
 
#56 ·
brlowe1965 said:
Well after reading all of these I have decided my 2.5 really sucks. My jeep is bone stock with 235 tires on it which I think are about 28 or 29". It is a 98 with 5spd. I get about 190 miles per tank and my mileage is right around 17-18. I have seen 19 maybe once. I'm rebuilding my 4.0 drive train to drop in it this year and hope not to loose to much on the MPG.

I wonder if some of the difference we are seeing in mpg is because people are running around with a speedo that is out of cal. I have checked mine with my GPS many times and it is within 1 mph at 65. By the way I comute 12 miles each way on the freeway with no traffic going about 70.

So put me in the 17-18 range.

Brandon
I'm sure that some of the padded results here are from out-of-cal speedos, but not all. My speedo isn't dead on either which is why I go by my GPS when I can. (it's in my carry-bag so it's always with me...)

But 17-18 is pretty good for a 2.5L...
 
#57 ·
I have a 93 YJ 4.0 5spd 31"GY MTR's and I get between 15-20mpg. if you keep it tuned up, replace your plugs, wires, cap/rotor, oil, filters (oil, air, fuel) lubricants in chassi and air in your tires like your supposed to, oh and clean your injectors every once in a while you might find that you will get some better mileage. I conversations that I have had w/ owners w/ the 2.5, i find that we get comparable milage. But I can out run them in the dirt and on the road 'cause I gots me sum bigger squirrels eatin the peanuts.
Oh and my speedo is w/in @ 1mph of true.
 
#58 ·
I'm running stock, approx 6000 miles on the TJ, and getting between 15-17. Longer runs (not pushing it), I definitely get over 17, but haven't broken the 18mpg mark yet.
 
#59 ·
Some of this mpg difference may be weight of vehicle-- stock YJs weighed less than stock TJs. Well-modified TJs with heavier axels, skids, rockers, bumpers, tire carriers, winches, etc., are going to drop a little mpg due to weight.
 
#60 ·
Ok, I'll include the milage from my last 10 refuelings to add some data to this discussion.

Data Representation
Since the TJ is not a daily driver and gets such crappy milage I only really use it for wheel'n. The below milage represents a combination between trail use and road driving. The road driving basically just includes milage to get to and from the trails and is usually on the freeway or state highways. I figure about 1/2 the time is spend on the road, the other half the time on the trails.

I have oversized tires on the TJ without a speedo gear change. When the speedo reads 60mph, the TJ is actually doing about 65mph. Dividing 65/60 gives me a correction multiplier of 1.083. I think should be reasonably accurate since the TJ is actually going faster (traveling farther) than the speedo indicates. The following data set has been corrected based on this value.

Milage Figures
15.3 mpg
15.4 mpg
14.1 mpg
14.1 mpg
14.1 mpg
15.7 mpg
14.6 mpg
13.5 mpg
11.3 mpg
13.4 mpg

TJ Setup
To augment the data above, my TJ has the following pertinent drive train/tire/gearing information:
  • 4.0L I-6 engine
  • 3 spd automatic transmission
  • 3.07 gears
  • 32x11.50 tires
 
#63 ·
Since I got it new in Setember, I've been getting about 17.5 hwy.
I do a lot of trips for work. Recently, I read about speed and mileage. So on my last trip, I ran a fairly consistent 65mph, instead of my normal 75-80mph.
I also ran 34lbs of air in the tires, and had just changed the oil. My bad I bought
5w-30 instead of 10w-30, but being still a bit cold out I figured I'll be good till I change it again.

Anyways that being told, My last trip 3 tanks of gas, and I got 20.3 20.1 and 19.3.
(The trip home I was doing over 70 most of the time.
 
#65 ·
I average about 12 mpg as I have a heavy foot. :eek:
My 9200lb powerstroke diesel van gets 19 mpg all day on the highway and 16 mpg towing a 5000 lb trailer. :cool:
Looks like I may flat tow my jeep when driving long distances for off road trips to save on gas. ;)
 
#68 ·
I got an easy 18mpg in 90* weather with myself and two other 180lb guys and all their **** driving back from NC last summer on stock 30's with 3.73 gearing...that was doing about 80-90mph also :laugh:. Now in city with my 31's I get about 15-6 sometimes and the occassional 14mpg :(. With 33's and 4.56's I dont expect much better hehe :drool:.
 
#70 ·
People may not believe me, but I got about 18.5 on my trip to Paragon... most of the time going 70-80mph. That's with a moderate load of camping gear in the rear and my winch on the front. It's also body lifted. Other than that, it's stock.

Normal driving to and from work I get 15-16.
 
#72 ·
If I don't drive with a heavy foot I can get around 18. I used to get around 20 with the hard top and 30" tires with no lift. I think if I put the heavy foot back on it would go back down easily to 13-14. It's all in how you drive I think. The higher in the air it goes the lower mpg you get also. Just forget checking it when the top is down. It sucks.

My $.02

Jim
 
#74 ·
Jerry Bransford said:
For some unknown reason, my mileage recently went up from an average of 12.5 to 14.5. I dunno why it did but I haven't seen 14.5 mpg in years, woo hoo! :thumbsup:
You too?!? My normal being around 11.5-13.5, my last two were 16.2 and 14.3. Weird...
 
#75 ·
My 87 yj got around 20 most of the time, sometimes better, with average highway driving. I live in the country and mostly rural roads and small towns so I consider it to be highway 60-70 mph driving. My 99 gets around 18.2 with the same type driving. That's without calculating for the 31's I have on it. I've not changed the speedo gear. However, having larger tires does not inflate the figures to the positive side (when not changing the speedo gear) but the oposite. For instance, if I travel 250 miles according to my odometer, I have actually traveled 257.5 miles. It is an insignificant amount of difference as the mileage for that tank of gas instead of being 17.85 mpg would be 18.39 mpg, not a big change. But if you are running 33's or better, without changing your speedo gear, your mileage might be significantly better than you are calculating, unless you are taking into consideration the actual miles traveled, and not what your trip meter is telling you.
I borrowed a calculator from a web page by Mark Medina and posted it on my site. http://www.281.com/fergy/calculators.html His original page works fine, but the table is too narrow making the cells not line up, so I stole his code and widened the table for speedometer calculation so the cells are in the right place. It also has calculators for tire size conversion from metric to inches and others.

I think the lighter yj's might be the reason for the better mileage, but you would think that the fuel injection would make up for it. My 87 had a carb. My 90 suburban with a fuel injected 350, loaded with my whole family of 5 with all our luggage for a 14 day tour through Colorado, got 18 average on that trip, with lots of mountain driving!

Having larger tires certainly makes your mileage go down, but calculating your actual mileage driven might pick up your numbers just a bit. :thumbsup:
 
#76 ·
fergyfer said:
If I travel 250 miles according to my odometer, I have actually traveled 257.5 miles.
Which is why I use my GPS for a true reading. At 200 miles (all I can get out of a tank, never dream of getting 250+) my odometer will be off by about 9 miles (tested in nearly strait line driving across Texas). And that's just with 31" tires.
 
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