3.7L Performance

[2002KJLimited]

Muffler delete

It's been a while since I lasted posted so I thought I'd update yall on how my system has been doing for the last few weeks. To all those nay sayers that said the muffler delete would hurt fuel economy I'm happy to report fuel economy is still were it was when the KJ had no mods, an amazing 16mpg or less. Since last posting I installed a firestik mount on the driver side of the rear and swapped my 12ft coax for firestik 18ft coax. This combined with the 5ft FS2 antenna produces a SWR of 1 on every channel. Reception and transmission sound amazing.

 

[JasonJ]

It's been a while since I lasted posted so I thought I'd update yall on how my system has been doing for the last few weeks. To all those nay sayers that said the muffler delete would hurt fuel economy I'm happy to report fuel economy is still were it was when the KJ had no mods, an amazing 16mpg or less. Since last posting I installed a firestik mount on the driver side of the rear and swapped my 12ft coax for firestik 18ft coax. This combined with the 5ft FS2 antenna produces a SWR of 1 on every channel. Reception and transmission sound amazing.

16 or less? Ick bud.. that *****. I never get less than 18MPG if I drive sanely.

 

[tommudd]

16 or less? Ick bud.. that *****. I never get less than 18MPG if I drive sanely.

Thats what I was going to say, I get way better than that ( the 04 with 32s, lots of heavy metal hanging on it , 4.10s always got 21-22 easy on the highway and in town better than 16 ) so.....
The 03 is averaging 19.75-20

 

[GunnerSchenck]

If anything that only builds the case of the "naysayers".. I drive like an ****** everywhere I go, and average 18.4 for the last 7600 miles.. probably 70-80% of which is "city driving"..
Why would you want to delete the muffler anyways? When I replaced my muffler I ran it just to hear the tone without one..and thought it sounded horrible.. wouldn't want my daily drivers sounding anything like that lol.. but your preference I suppose. I'll stick with the sound of a properly functioning exhaust..

 

[tommudd]

My buddys rusted off on his 03, he said he was going to run it like that for a while till he had time to repair it. Didn't take him long though, said mileage took a crap, sounded horrible so, didn't have the power it did . This was an 03 he bought new, had about 190,000 on it at that time so he knew how responsive it was, what mileage was like for many miles .

 

[tjkj2002]

Thats what I was going to say, I get way better than that ( the 04 with 32s, lots of heavy metal hanging on it , 4.10s always got 21-22 easy on the highway and in town better than 16 ) so.....
The 03 is averaging 19.75-20

I get 6-7 in town:hidesbehindsofa:

But can still pull 18 on the highway.:favorites37:

 

[Dave]

I get 6-7 in town:hidesbehindsofa:

But can still pull 18 on the highway.:favorites37:

6-7 in town?.....(18 highway is respectable though) but yours is different. It's a overweight heavy porker......LOL

Dave

 

[HoosierJeeper]

Got mine when it was 2 years old with 37k. Never got more than 16 in the city/rush hour mixed stock back in FL. Now I get about 13-14 once winter is over, all city. Highway, can usually get 20ish going 70-75. The KL gets about 15-17 all city, 24-25 highway.

 

[rockdart]

I've been getting 15.5 - 16.5 in town. From the UT state line to Provo, I got 19.5. The trip back I'm not counting since I was doing 95-100mph most of the time through WY.

 

[Myke]

I was getting 17mpg avg before lift and tires on my current 03. Will have to watch and see what I get with 32" tires now.

When I had my 02 i was getting 19-20 before lift/tires. Then 11-12 on 265/70/16 kumho mtrs with 2.5" lift.

On my 2010 kk I was getting 21-23mpg avg. If I kept it under 45mph i could do 27-29mpg.

And didn't have the 07 very long to pay attention.

Sent from my SM-N910V using Tapatalk

 

[Dave]

Pre lift I could get 16 in town and 20 to 21 ish highway.

Now with the lift and bigger tires and no gear changes I am lucky to get 12-14 in town and 18-19 on the highway and that is on the average. I have had my EVIC telling me 10-11 sometimes too. Winter gas and letting it idle with the heater on doesn't help in winter when it is really cold. MPG improves a little in the warmer weather.

Dave

 

[tommudd]

I was getting 17mpg avg before lift and tires on my current 03. Will have to watch and see what I get with 32" tires now.

When I had my 02 i was getting 19-20 before lift/tires. Then 11-12 on 265/70/16 kumho mtrs with 2.5" lift.

On my 2010 kk I was getting 21-23mpg avg. If I kept it under 45mph i could do 27-29mpg.

And didn't have the 07 very long to pay attention.

Sent from my SM-N910V using Tapatalk

I drove my 04 for a short time until the 4.10s were installed , dropped about 5-6 MPG on the highway and no power at all , kept shifting all the time. Hated to drive it , was actually thinking of taking the 265-75s off until I could have the time to regear it.
With the 03 with 265-70-16s ( before regear,) it dropped to 16-17, now with 4.10s back up where it should be

 

[Myke]

I drove my 04 for a short time until the 4.10s were installed , dropped about 5-6 MPG on the highway and no power at all , kept shifting all the time. Hated to drive it , was actually thinking of taking the 265-75s off until I could have the time to regear it.
With the 03 with 265-70-16s ( before regear,) it dropped to 16-17, now with 4.10s back up where it should be

Yeah I'm gonna look for 4cyl axel and diff for an easier swap. Under 55 w/ od off its no problem. Just doesn't like uphill at 55-65mph.

Sent from my SM-N910V using Tapatalk

 

[tjkj2002]

6-7 in town?.....(18 highway is respectable though) but yours is different. It's a overweight heavy porker......LOL

Dave

I live at 6200',work at 6800',and the KJ as it sits as of right now officially weighs 6450lbs without me in it(full tank of gas).That is 650lbs over the max GVWR of a KJ,glad DOT doesn't spot check passenger vehicles.

 

[Jim McClain]

Mileage? I've never figured it out. I don't wanna know. I already know fun ain't cheap.

 

[uss2defiant]

IMHO, everyone's jeep is different, mechanical condition, lifted/unlifter, roof rack no roof rack. Many variables contributing to MPG. Driving style, environmental factors.
How does one even calculate their MPG? via EVIC? Odometer/fuel usage manual calculation?

Comparing apples to oranges...

 

[tommudd]

miles per gallons of gas used
plus scan gauge

 

[tommudd]

Mileage? I've never figured it out. I don't wanna know. I already know fun ain't cheap.

Oh I don't know always ways to have cheap fun

 

[JasonJ]

IMHO, everyone's jeep is different, mechanical condition, lifted/unlifter, roof rack no roof rack. Many variables contributing to MPG. Driving style, environmental factors.
How does one even calculate their MPG? via EVIC? Odometer/fuel usage manual calculation?

Comparing apples to oranges...

EVIC, reset at specific times and conditions to get a realistic average; I also do the gallons used/miles driven method to compare, and I've found EVIC is damn accurate (for me at least). The longer I allow EVIC to calculate the more accurate my long term fuel efficiency is displayed.

Sometimes I reset EVIC to get an avg for a specific trip or while driving to get a short, real-time avg.

 

[2002KJLimited]

Again It's been a while, school occupied me. My jeep is lighter than most as I removed the front skid plate and the rest of the car is stock except for my performance mods. Even though my mpg's aren't great, I definitely feel that the engine is more responsive and the torque band feels wider. It puts a smile on my face every morning and there's nothing like seeing angry faces as you scream past slow pokes on the highway. I also have an exhaust extension past the cat that is a foot long and has a 45 towards the ground (same diameter too), this sounds much better than nothing after the cat.