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Miles per gallon help

4K views 21 replies 11 participants last post by  4.whoa 
#1 ·
What are some ways to improve the mileage on my 4.0L wj? I'm getting 14mpg and I'd like to get it a little higher. Is it true that flowmasters give you an extra 2mpg?
 
#2 ·
If you're really worried about gas mileage, I suggest you look at a different vehicle. I have the same engine as you, and get worse gas mileage, but only because I don't really stay on top of my tire inflation as much as I should. That's one thing that can help:make sure you have fully inflated tires. Sounds simply but can make a huge difference.
 
#4 ·
Is this the average mpg? It all depends on how you drive and if you drive mostly highway or city. If this mpg would be from highway driving only, then something is wrong. Is the preventive maintenance done in time? ( plugs, air filter)
If that is ok, it could be a problem with a bit too low fuel pressure. A new filter/pressure regulator assy would be a cheap fix.
But tire pressure as fin1211 mentioned is also a factor.
 
#6 ·
A few years ago I owned a 1992 Cherokee Laredo with the 4.0L engine. I added a "cold air intake" which removed the restrictive factory air box plus I installed a cat-back Dynomax exhaust. The engine performance increase was noticeable. It no longer felf choked off IMO. My MPG went up 2mpg in mixed driving. I was getting about 18mpg average after the mods.
 
#8 ·
I used to have a 97 ZJ 4x2 with the 4L I6. When it was stock I averaged 18 MPG. I installed a K&N CAI, a Fastman TB, a Banks Torque Tube header, and had a custom 3" exhaust made. Then I started averaging about 22 MPG with my best recorded trip of 25 MPG. So, after installing about $2K of stuff (including a Hypertech tuner) on my $9K Jeep, I got about a 20% improvement in fuel economy.

However, the thing that made the most difference, was my right foot
 
#12 ·
I don't have my foot in it so better air filters and i don't think I want a noisy jeep. I like it quite gotta stay under the radar haha I have been thinking about a new fuel pump as well. We just got a nasty 10 ich snow storm in Kansas City and I got 8 mpg in 4x4..... That was depressing! But the ole girl handled like a dream
 
#13 ·
you didnt mention it but if you have larger than stock tires youre mileage is not going to be accurate nor is the odometer
Tire size calculator

scroll down to where you enter youre tire size make sure you enter it as they have it with the / after the aspect and - before diameter than you will get a percentage differance from stock to what you have now apply that to youre readings and see if that helps. of course if you have stock tires than, nevermind:)
 
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