[pclaptop]

Has anyone found or is there any modifIcations to the 4.0l 6, to improve gas mileage above 20mpg?

I'm not interested in more power, just the best gas mileage i can achieve

thanks pclaptop

 

[rockwe31]

Make sure you are using factory sized tires, have all your regular maintenance caught up, and drive slow lol. 20 mpg is great from an early 00s SUV. There’s no magic mod for better mileage.

 

[pclaptop]

When you say "early '00s" SUV is that to imply better fuel mileage improvements were made on newer Jeep Grand Cherokees?

Can you expound on what they might have been?

thanks pclaptop

 

[rockwe31]

The early 00s were the gas guzzler era; think Hummer, Ford Excusion, etc. Gas was cheap so there was not a big emphasis on gas mileage when producing vehicles. Now there’s a much bigger emphasis on gas mileage. Aerodynamics are improved, smaller and more efficient engines are used, tech such as active fuel management and auto stop/start exist. With almost any 20 year old vehicle your expectations for gas mileage and performance have to match that of that time, not the present.

 

[pclaptop]

Are there "headers" made for the 4.0l engine in my '03 Grand Cherokee? I understand there are standard exhaust manifold mufflers addons to be had but they are mainly for power or sound changes.

Would headers help/increase gas mileage?

Expensive?

pclaptop

P.S. Any other mileage improving addons?

 

[Mr. Mike]

Once upon time there was a popular swap mod replacing the stock 4.0L single hole injectors with Dodge Neon 2.0L four hole injectors.
Supposedly the better fuel atomization made for a smoother idle and slightly improved gas milage.
IDK if the information still out there but you might want to look at what's involved.

 

[fred rupert]

Once upon time there was a popular swap mod replacing the stock 4.0L single hole injectors with Dodge Neon 2.0L four hole injectors.
Supposedly the better fuel atomization made for a smoother idle and slightly improved gas milage.
IDK if the information still out there but you might want to look at what's involved.

I have some bosch 4-hole in my 4.0L, (do not know their original application), but idle is butter smooth. I have made some other modifications including a larger throttle body, 1.7:1 roller rockers, free-flow exhaust, 4.11 gears & 20" TrackHawk rims. I put my foot in it & still avg. 19mpg.