Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (
-   Performance Modifications (
-   -   Miles per gallon help (

nickmuller 02-13-2013 09:59 PM

Miles per gallon help
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?

fin1211 02-13-2013 10:09 PM

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.

nickmuller 02-14-2013 10:25 AM

I was thinking about opening up the exhaust and intake I hear that helps. I love my jeep to much to get rid of it!

Frango100 02-14-2013 01:29 PM

Re: Miles per gallon help
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.

tcolin2351 02-18-2013 07:24 AM

I have a 5.7 HEMI in my WK and was getting about 10.5 around the city. I just got some fuel injector cleaner and cleaned my air filter, that seemed to help...

SteelBlueWK 02-18-2013 07:31 AM

Re: Miles per gallon help
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.

4.whoa 02-19-2013 04:38 AM

Re: Miles per gallon help
I've always gotten 17+ on all my 4.0's- except for @ the track and 20 avg hwy with the 5spd's

whats your setup?

zlartibartfast 02-19-2013 08:31 AM

Re: Miles per gallon help
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

fin1211 02-20-2013 05:06 PM

Got tires to what they're supposed to be, reset the computer, and averaging ~17mpg in...village driving? Some stop and go, but not much.

I can tell ya one thing-tire pressure makes a huge difference!

jerkylips 02-20-2013 06:07 PM


Originally Posted by 4.whoa (Post 762776)
I've always gotten 17+ on all my 4.0's- except for @ the track

4.0 at the track. For some reason that made me laugh. Great engine, but I wouldn't call it "fast".

fin1211 02-20-2013 06:27 PM


Originally Posted by jerkylips (Post 764144)
4.0 at the track. For some reason that made me laugh. Great engine, but I wouldn't call it "fast".

No, no not at all.

nickmuller 02-21-2013 11:26 PM

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

All times are GMT -5. The time now is 01:22 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community