KK Poor Gas Mileage

sean1214 · **Posted:** Tue Sep 06, 2016 11:47 pm

I know our Libbies aren't known for getting stellar gas mileage, but reading through the forums I feel mine is much worse than everyone else. Hypermiling the best I've been able to get is 12 city and 16 hwy no matter what time of the year/blend of gas. I know its not my driving habits because I can get over EPA on every other car I drive.

Are there any known issues that could cause this (such as dragging e-brake?) as I'm tired of getting only 200 miles out of a tank. Its entirely stock and riding on the wrangler sra's :furious:

Also is there anything that could help?

PALiftedKK · **Posted:** Tue Sep 06, 2016 11:55 pm

depends on what mods you did and what type of maintenance you have done.

low mileage is a thing on a lot of KKs. a lot of us get any where from 11 to 14 mpg in the city and 16-21 highway.

also, winter fuel really only drops our mileage by 1 mpg. you living in cali year round have bad gas regardless. 12 is decent for where you live if your modified.

tommudd · **Posted:** Wed Sep 07, 2016 12:58 am

First question is how many miles since you replaced the spark plugs with a good set of NGK or Champion coppers

lfhoward · **Posted:** Wed Sep 07, 2016 9:53 am

I was going to suggest new copper spark plugs like Tom said, but I'll also add that a clean engine air filter helps too. If it were me I would also try running Lucas fuel treatment through a couple of tanks of gas to clean out the gunk from your injectors. Alternatively you could run Shell V-Power gas for the next couple of tanks because it has extra detergents that will do the same job of cleaning your injectors. No need to stay with high end gas longer than a couple of tanks though because our engines were designed to run best with 87 octane and you'd be wasting money.

sean1214 · **Posted:** Wed Sep 07, 2016 10:37 am

Right now its completely stock unless plastidip is a mod :ROTFL:

Spark plugs haven't been touched since I got it at 65K (now just shy of 80k) and same with the air filter. Would changing to a K&N drop in help much? I'll pick up spark plugs when I have the chance because I don't how long they were on there with the last owner....

I really want to throw in the 4.7 TB but I'm worried about it not passing smog. CA will literally fail you for anything... :banghead:

lfhoward · **Posted:** Wed Sep 07, 2016 11:38 am

If I were you I would try to solve the fuel economy problem before adding in other variables like the 4.7 TB. The K&N doesn't seem to do much except provide a satisfying sucking sound in the KK, so most would say it isn't worth your while. The stock air box provides more than adequate air flow and the stock filter keeps the dirt out of your engine better than a K&N.

But back to your spark plugs: if they haven't been changed out in the last 80K miles then that is easily the issue. The plugs need to be changed every 30K or the gaps widen due to wear which reduces fuel economy and power. Take Tom's advice and use plain old NGK coppers not fancy iridiums or platinums when you do the swap. The 3.7 is much happier with basic coppers, according to the folks with the most experience on here. Plugs are easy to change on this engine so no need to get fancy.

tc1uscg · **Posted:** Wed Sep 07, 2016 3:58 pm

My KK loadout nets me around 11 city. I have not run on the hwy for long with the winch on, which (no pun) adds only about 60 lbs to the front at most. But after adding the bigger tires, the full skids, sliders, class 3 hitch, and the couple of hundred pounds I carry in the back end (chains, air pump, tie downs, zombie/buggout bag backpack, and loose change in the console, I'm pushing 5k lbs. That's why I put the lift on, to get it's belly off the round. Let my daughter borrow the jeep this weekend to drive to Fire Keepers Casino. I got the rig back with just under 1/4 tank. So, figured she drove about 290 miles round trip so that got me about 18 mpg. Had taken off the roof rack (less drag), just cleaned the K&N. Tires aired to 45psi (she did complain about the noise, those duratracs are noisy now they are hitting 18 months old. She drives it under 2000rpm so thats about 62mph. No rain and it also was freshly waxed. So, for a brick, it was bout as smooth as it was gonna get.

OutaLines · **Posted:** Thu Sep 08, 2016 12:30 pm

You may have some significant carbon buildup in your engine as well as needing new plugs. I'd get some seafoam and run that through the intake. Depending on the amount of buildup, you may want to do the cleaning 2 or more times. Check out some YouTube videos if you haven't used it before. You can run some royal purple fuel system cleaner through a tank of gas too. Installing a new fuel filter wouldn't be a bad idea either. I just got my Libby, too and I had slightly lower than expected mpg, allong with a Very significant lag in throttle response. I tried these along with a k&n air filter and throttle body spacer. All that got me an extra 3.5 to 5 mpg depending on AC running or not. Not sure how accurate the Torque App is, but the difference before and after should be correct. I'm yet to install new plugs or a fuel filter, but I hope those will give me an extra boost as well. Here's hoping you get similar results or better.

Sent from my SM-G900V using Tapatalk

tjkj2002 · **Posted:** Thu Sep 08, 2016 6:53 pm

OutaLines wrote:

You may have some significant carbon buildup in your engine as well as needing new plugs. I'd get some seafoam and run that through the intake. Depending on the amount of buildup, you may want to do the cleaning 2 or more times. Check out some YouTube videos if you haven't used it before. You can run some royal purple fuel system cleaner through a tank of gas too. Installing a new fuel filter wouldn't be a bad idea either. I just got my Libby, too and I had slightly lower than expected mpg, allong with a Very significant lag in throttle response. I tried these along with a k&n air filter and throttle body spacer. All that got me an extra 3.5 to 5 mpg depending on AC running or not. Not sure how accurate the Torque App is, but the difference before and after should be correct. I'm yet to install new plugs or a fuel filter, but I hope those will give me an extra boost as well. Here's hoping you get similar results or better.

Sent from my SM-G900V using Tapatalk

Never use seafoam in a engine with a plastic intake,terrible cleaner anyways and is to corrosive for the plastic intakes.

Only use approved throttle body and upper end cleaners.

K&N air filters are for racing,actually allows more dirt into the engine.Plenty of independant tests to prove that out there.

Throttle body spacers do absolutely nothing for a multi-port FI engine also.No fuel actually travels through the intake which is what throttle body spacers need to work. Throttle body injected engines and crab'd engines see a good increase but on a multi-port FI engine it just drains your wallet.

On a side note a clean air filter has nothing to do with mpg's and hasn't since 1996.A 85% clogged air filter will actually get you better mpg's,less power but more mpg's.The PCM knows that less air is entering the engine thus less fuel is put in.

PALiftedKK · **Posted:** Thu Sep 08, 2016 8:11 pm

^^^ yep!

since your all stock and dont know the previous history of the engine you should definitely replace the spark plugs with ngk, basically go to mopar ans ask for them. that paper air filter is stupid restrictive and if its never been changed you should either replace it with a paper filter or use a low grade cotton filter (spectre air filter). a K&N drop in filter would be of little benefit to power and mpg.

tjkj2002 · **Posted:** Thu Sep 08, 2016 8:21 pm

PALiftedKK wrote:

^^^ yep!

since your all stock and dont know the previous history of the engine you should definitely replace the spark plugs with ngk, basically go to mopar ans ask for them. that paper air filter is stupid restrictive and if its never been changed you should either replace it with a paper filter or use a low grade cotton filter (spectre air filter). a K&N drop in filter would be of little benefit to power and mpg.

Actually not true.

3 of the 5 best flowing air filters tested are paper.Only resean K&N flows the best is it doesn't actually filter much(hence why it's for racing only).

sean1214 · **Posted:** Fri Sep 09, 2016 6:16 pm

Plugs should be changed within the next week or so, depends on if I can find some time. If not I'll have the dealer do it for me. I aired up my tires and am running shell 91 through it right now, so hopefully that helps a little bit. I shouldn't have a problem with carbon buildup as I commute into the mountians (seasonally) with it so it sees high rpms very often. Plenty of chances for it to clear its throat.

As for an air filter I'll stay stock for now if there is no benefit changing to a high flow. I don't know if an exhaust would help either but I kinda want an excuse to get some sound out of it :rockon:

Thanks for the help.

OutaLines · **Posted:** Mon Sep 12, 2016 12:26 pm

So, I wont be putting Seafoam through my intake ever again. Thanks, tjkj2002. I do believe that the majority of my issues that pertain to you were resolved by the engine cleaning and less from the filter/TBS changes. I got a measly 1-2 mpg from the filter swap, but some better response. The bulk of my mpg gains came after running the cleaners through the engine. Although I didn't get any mpg gains at all from the TBS, I did notice difference in engine response after bolting that on. In Hindsight, I can't really recommend spending the $100+ to get what I got, but back when I had a 4.0 Wrangler I sure noticed a difference. It is true that changes to the KK's intake typically won't make much of an impact, because this engine really doesn't have an issue getting air in, but what is happening to the exhaust on it's way out... If you don't see any changes after cleaning and plugs, check your cats and muffler for any problems and replace as needed. A failing exhaust can cause mpg losses, depending on where/what the problem is. As for upgrades like High flow components, diameter changes, and types of manifolds or headers? Those depend on what you want to get out of your engine. That's my next undertaking before a lift is in order.

sean1214 · **Posted:** Mon Sep 12, 2016 6:35 pm

OutaLines wrote:

check your cats and muffler for any problems and replace as needed. A failing exhaust can cause mpg losses, depending on where/what the problem is.

Hhmmmm I do have a clicking/ticking sound in my exhaust.... Is that of concern?

tc1uscg · **Posted:** Tue Sep 13, 2016 8:29 am

sean1214 wrote:

OutaLines wrote:

check your cats and muffler for any problems and replace as needed. A failing exhaust can cause mpg losses, depending on where/what the problem is.

Hhmmmm I do have a clicking/ticking sound in my exhaust.... Is that of concern?

Only if the ticking follows you inside your home. :dizzy:

tc1uscg · **Posted:** Tue Sep 13, 2016 8:39 am

sean1214 wrote:

I know our Libbies aren't known for getting stellar gas mileage, but reading through the forums I feel mine is much worse than everyone else. Hypermiling the best I've been able to get is 12 city and 16 hwy no matter what time of the year/blend of gas. I know its not my driving habits because I can get over EPA on every other car I drive.

Are there any known issues that could cause this (such as dragging e-brake?) as I'm tired of getting only 200 miles out of a tank. Its entirely stock and riding on the wrangler sra's :furious:

Also is there anything that could help?

I have an 02 and 09. I've seen lots of talk about MPG. First off, it's a Jeep (Chryslers product). Chrysler can't produce a car/truck that gets decent MPG even if Volkswagen handed them the software :-)r

. That's the personality of these vehicles (the norm). People have gone back and forth over K&N, AMSOIL, yada yada yada. If you get 1 mpg over the EPA stated number, consider yourself in the top 1% of KK/KJ owners (based on my experience of the 2 I own and 1 I rented for 3 years) Or you are going down hill with the wind to your back. The moment we Jeeperize our rigs or even THINK about it, we see our numbers drop. That's the nature of the beast and lower than normal MPG is an option you won't see on the window sticker but you do still the fake EPA ratings. The only car that I have in my drive that gets way above the EPA estimate is the 2013 VW TDI. And yep, as per the tree huggers out in California, it's polluting the world :grim:

. But no more then that big F250 rolling thunder I was behind last night but hey, I'll be dead and gone before I see a hint of the effects on our planet :dead:

.

The best I ever got with my KK was 26mpg. Driving 60mph on I-94 (mostly flat) from Detroit to Chicago and back. But that was ONE time and stock. Heck, I even got 32 out my 2011 Town&Country from St. Ignace Mi to Green Bay WI. On a trip recently from Detroit to Baltimore and back, 29.7. Funny how driving 55-60 will increase the mpg :shock:

. I get about 200 miles from my tank too with 90% city driving. I don't even look at it anymore. I just drive it and enjoy the wine from my goodyear duratracs. :rockon:

Bmxer524 · **Posted:** Tue Sep 13, 2016 4:25 pm

tc1uscg wrote:

sean1214 wrote:

I know our Libbies aren't known for getting stellar gas mileage, but reading through the forums I feel mine is much worse than everyone else. Hypermiling the best I've been able to get is 12 city and 16 hwy no matter what time of the year/blend of gas. I know its not my driving habits because I can get over EPA on every other car I drive.

Are there any known issues that could cause this (such as dragging e-brake?) as I'm tired of getting only 200 miles out of a tank. Its entirely stock and riding on the wrangler sra's :furious:

Also is there anything that could help?

I have an 02 and 09. I've seen lots of talk about MPG. First off, it's a Jeep (Chryslers product). Chrysler can't produce a car/truck that gets decent MPG even if Volkswagen handed them the software . That's the personality of these vehicles (the norm). People have gone back and forth over K&N, AMSOIL, yada yada yada. If you get 1 mpg over the EPA stated number, consider yourself in the top 1% of KK/KJ owners (based on my experience of the 2 I own and 1 I rented for 3 years) Or you are going down hill with the wind to your back. The moment we Jeeperize our rigs or even THINK about it, we see our numbers drop. That's the nature of the beast and lower than normal MPG is an option you won't see on the window sticker but you do still the fake EPA ratings. The only car that I have in my drive that gets way above the EPA estimate is the 2013 VW TDI. And yep, as per the tree huggers out in California, it's polluting the world :grim:

. But no more then that big F250 rolling thunder I was behind last night but hey, I'll be dead and gone before I see a hint of the effects on our planet :dead:

.

The best I ever got with my KK was 26mpg. Driving 60mph on I-94 (mostly flat) from Detroit to Chicago and back. But that was ONE time and stock. Heck, I even got 32 out my 2011 Town&Country from St. Ignace Mi to Green Bay WI. On a trip recently from Detroit to Baltimore and back, 29.7. Funny how driving 55-60 will increase the mpg :shock:

. I get about 200 miles from my tank too with 90% city driving. I don't even look at it anymore. I just drive it and enjoy the wine from my goodyear duratracs. :rockon:

So true, no Chrysler corp vehicle ever gets good mileage. My finance's 200S convertible pulls low to mid 20s with me driving it. And they claim the new 3.6 Pentastar was efficient :roll:

(maybe at making power I guess, yet my mom's 2014 Impala pulls way harder with a similar displacement v6). A lot of what Chrysler is known for still sticks, electrical problems, poor gas mileage, and in general slow trucks. Some of their trucks might be powerhouses, but still slower than some other trucks out there.

Sean, where in Cali are you located? I know some of Cali gets pretty mountainous so it could explain slightly worse gas mileage. Your fuel doesn't help either, Cali is known for that garbage they call gas. I'd just do the regular maintenance; so air filter, spark plugs, oil change, try changing the tranny and transfer case fluid as well as front and rear diff fluid. That gives you a clean slate to start working with and see what you get.

KK Poor Gas Mileage

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