FAQ - My gas mileage sucks - Page 5 - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > General Technical Discussions > Engines & Drivetrain > FAQ - My gas mileage sucks

Rough Country Lift Kits and Parts!XJ Rail Sale!The Ruffstuff NOT Universal 4 Link Kit!

Reply
Unread 11-23-2012, 07:24 PM   #61
dsodko
Registered User
2002 WJ 
 
Join Date: Aug 2008
Location: Georgia
Posts: 214
Great posts. I would like to add my mods for my late 1994 4.0 I6 Grand (totaled in a wreck !). Amsoil in engine, trans & diff. Stock rear end w/new axles & bearings. Throttle body & injector cleaning. Tune up: E3 plugs, wires, cap. New serpentine belt & idlers. New exhaust & intake manifold, gasket and intake & exhaust port cleaning. I regularly was getting 22MPG ! For Atlanta driving and our heat and humidity, I was pleased.

dsodko is offline   Reply With Quote Quick reply to this message
Unread 12-27-2012, 08:31 PM   #62
05rubimike
Registered User
2005 TJ Wrangler 
 
Join Date: Jan 2012
Location: Glen Ellyn, IL. 60137
Posts: 8
Posts are Okay, truth is Jeeps don't get the greatest MPG's. I averaged for the six months earlier this year, once or twice a month . After hundreds spent I found my absolute average was 13.8 MPG. That's after a spark plug change and 02 sensor's (all 4). I'm at 74,500 miles currently and when I first got my '05 Rubicon I averaged about 17 mpg. What effects MPG's the most in newer generation vehicles is a DIRTY M.A.F sensor(very easy to clean). Driving style has an effect on gas mileage, but if your working with drive by wire like most new generation jeeps you only have so much control over throttle response and fuel consumption. Your computer picks up on your driving style and learns your pattern and habits then creates the most efficient vehicle for your style of driving. It's called OBD-2.
05rubimike is offline   Reply With Quote Quick reply to this message
Unread 04-24-2013, 01:05 AM   #63
Speedymcracer01
Registered User
 
Join Date: Feb 2013
Posts: 663
Quote:
Originally Posted by 05rubimike View Post
Posts are Okay, truth is Jeeps don't get the greatest MPG's. I averaged for the six months earlier this year, once or twice a month . After hundreds spent I found my absolute average was 13.8 MPG. That's after a spark plug change and 02 sensor's (all 4). I'm at 74,500 miles currently and when I first got my '05 Rubicon I averaged about 17 mpg. What effects MPG's the most in newer generation vehicles is a DIRTY M.A.F sensor(very easy to clean). Driving style has an effect on gas mileage, but if your working with drive by wire like most new generation jeeps you only have so much control over throttle response and fuel consumption. Your computer picks up on your driving style and learns your pattern and habits then creates the most efficient vehicle for your style of driving. It's called OBD-2.
I have a 98 grand cherokee laredo i6 4.0 it got around 15 mpg sence then i get about 12 mpg. mpg has went up by .2mpg just from replacing the front sway bar bushing i done a good bit of work to it the issue right now with the gas mileage is my exhuast leak it's before any sensors wich is causing it to readjust the fuel air mixture when it shouldn't be.but thier is alot of ways to maintaine and improve your gas milage short term would be suspention components tires alignments things like that then you got long term like keeping fluids changed and topped off the type of plugs you use anything like that affects gas milage i ran 93 octane in it for a while seemed to get better gas milage but infact it didnt my Jeeps computer is programed for 87 octane so it gets its best mpg with 87 the only thing 93 octane fuel did was crank my jeep the first time because 87 octane i would either have to turn it over twice before it would start or i could prime it turning the key over acouple times then it would start but now it only does that every once in awhile
Speedymcracer01 is offline   Reply With Quote Quick reply to this message
Unread 04-24-2013, 08:08 AM   #64
Speedymcracer01
Registered User
 
Join Date: Feb 2013
Posts: 663
Quote:
Originally Posted by Ruffnek View Post
Aren't all your fluids warm when the engine is running?

Certain things will help gas mileage...so don't say it can't be done, is there a quick fix to make a vehicle get 25MPG instead of 15? No...

A snorkel will decrease gas mileage, the longer, rougher, or smaller ID any pipe is causes more friction with the fluid flowing through it (Harder to pump or suck through it)
Cold Air Intake will get you better gas mileage with its smooth walls and large ID, not to mention larger surface area filter. Same idea with exhaust, larger ID exhaust with mandrel bends will flow better, using less power to push gases through. Take it further with ported and polished heads, look at a Hesco head and tell me smooth, larger bore piping doesnt flow better, they net 30 hp...and yes that will equal MPG's if you aren't on the gas all the time.

A programmer can get you better MPG
Free spinning hubs
Fuel Catalyst-(or so I've been lead to believe, haven't tried it myself)

But all that other stuff about weight and roof racks and filters is true too
What gets me is people putting cold.air intakes and **** on vehicle's but they do nothing to the exhaust or anything then they go around talking like oh yea the cold air intake made a big difference don't they know just because.you slap a cold air intake on only really changes the sound of the air beinig sucked into the intake but come on kinda pointless in my book. if you increase your vehicles air intake then you need to go ahead and increase the exhaust flow to actually achieve more power i put a short cold ram air intake on my focus sounded better but no change in power or torque threw a 3A racing exhaust under it was suppose to improve torque and horse power. i beleive it now i wasnt five mins out of the muffler shop before i had already out ran the sheriffs deputy's it made a big difference i got away from city county and state in that car it had a 2.0 dohc i was racing. 5.9 liters we never gained a lick on each other we was nose and nose the whole way to bad i never got to see how it ran with the super charger on it. It blew up before i got that on it though
Speedymcracer01 is offline   Reply With Quote Quick reply to this message
Unread 04-27-2013, 05:52 PM   #65
Soldier905
Registered User
1988 MJ Comanche 
 
Join Date: Apr 2012
Location: , michigan
Posts: 70
Quote:
Originally Posted by Speedymcracer01 View Post
What gets me is people putting cold.air intakes and **** on vehicle's but they do nothing to the exhaust or anything then they go around talking like oh yea the cold air intake made a big difference don't they know just because.you slap a cold air intake on only really changes the sound of the air being sucked into the intake but come on kinda pointless in my book. if you increase your vehicles air intake then you need to go ahead and increase the exhaust flow to actually achieve more power i
I agree on improving the exhaust if your going to improve the intake but your wrong on the the cold air intakes just being a noise maker , I installed a cold air intake on a 6.0 engine (suburban 2500) and got 2mpg more out of it (old filter was still clean ) while leaving the exhaust alone. The stock intake on some vehicles are just a complete joke its no wonder why they get poor mpg which is why the cold air intakes give such improvements . On the suburban i mentioned above the stock intake was a maze which made unnecessary turns and went from one side of the vehicle to the other side with no other ducting on other side.

On the jeep 4.0s ive yet to see a decent cold air intake made for them yet .
Soldier905 is offline   Reply With Quote Quick reply to this message
Unread 04-28-2013, 09:30 AM   #66
Speedymcracer01
Registered User
 
Join Date: Feb 2013
Posts: 663
Quote:
Originally Posted by Soldier905 View Post

I agree on improving the exhaust if your going to improve the intake but your wrong on the the cold air intakes just being a noise maker , I installed a cold air intake on a 6.0 engine (suburban 2500) and got 2mpg more out of it (old filter was still clean ) while leaving the exhaust alone. The stock intake on some vehicles are just a complete joke its no wonder why they get poor mpg which is why the cold air intakes give such improvements . On the suburban i mentioned above the stock intake was a maze which made unnecessary turns and went from one side of the vehicle to the other side with no other ducting on other side.

On the jeep 4.0s ive yet to see a decent cold air intake made for them yet .
Nice to know i might take my cold air intake and install it on my jeep lol
Speedymcracer01 is offline   Reply With Quote Quick reply to this message
Unread 05-12-2013, 05:56 AM   #67
DAVIDJAIKEN
Registered User
1998 XJ Cherokee 
 
Join Date: May 2013
Location: GILLINGHAM, KENT
Posts: 1
Mpg

Well, after a test I am getting 18.2 mpg as 75% of this was round town its better than I expected! Its all down to how you drive, and yes, dont pull away to slowly!! Also here in the UK fuel is 6.70p per gallon!!! Thats about $10.29c!!! David
DAVIDJAIKEN is offline   Reply With Quote Quick reply to this message
Unread 05-13-2013, 04:09 PM   #68
edpmedic
Registered User
1995 ZJ 
 
Join Date: Nov 2011
Location: Baldwin, NY Long Island
Posts: 1,049
Let me throw this out there. I am now driving a Ford Explorer with a 4.0L. 2002 Eddie Bauer package. I'm getting 13.6mpg around town. Highway its stable at 16.7mpg. The computer info center is close to my log calculations. That's a 6cyl. where I was worried about my Grand Cherokee with a 8cyl and worried about 17.6 or close to 18.5mpg before the flood from Sandy took it, with the Kolac exhaust with headers. I wonder if he makes a exhaust for a Explore, though I hope to be back in a GC soon.
edpmedic is offline   Reply With Quote Quick reply to this message
Unread 05-17-2013, 09:36 PM   #69
enkeivette
Registered User
 
Join Date: Mar 2013
Location: Placentia, CA
Posts: 119
Quote:
Originally Posted by Willy36 View Post
AFAIK, any vehicle with electronic fuel injection will do this. I know for a fact the Renix 4.0 (87-90) will cut all fuel under closed throttle conditions above 1200 RPM (I assume it kicks back on at 1200 in case it's dropped out of gear quickly so it doesn't stall). With my manual trans, I can actually feel the injection cut back in when coming to a stop.



Only with mechanical fuel systems (ie carbed or TBI). The pistons are still moving because they're indirectly connected to the wheels which are being forced to turn by the momentum of the vehicle. This is why engine braking works...It wouldn't work real well if the engine was still getting gas, would it?



It makes a difference when used properly. I saw around 2 more mpg average when I started engine braking, even just in the city. When driving in really hilly areas, it can be even more (pushed 24 MPG on a trip down from the mountains once )

I would guess the system is tuned for the best balance of power/emissions/mileage. If you were to tune for purely mileage or mileage/power and forget emissions, I'm sure you could do better. But you'd have to know what you were doing to keep the engine running safe.

False, if the pistons are moving, without cylinder deactivation they're sucking in fuel. Not to mention it would lean spit if the AFR got too high. Not to mention the rumbling noise your engine makes on decel is evidence of internal combustion (meaning, FUEL, air, and boom).
enkeivette is offline   Reply With Quote Quick reply to this message
Unread 09-09-2013, 09:21 PM   #70
jurczak8
Registered User
2009 JK Wrangler 
 
Join Date: Sep 2013
Location: Danville, IL
Posts: 1
Whats going on?! Just Purchased my first 2009 Jeep Wrangler. I just put a 4" lift on it with 20's (Motor Metals) and 35's (Nitro) rims and tires. I have seen all kinds of kits and different things to purchase to increase HP and MPG. I was just wondering what would be the best thing to buy to increase a little bit of both?!?!?

Thanks!
photo-9-.jpg

jurczak8 is offline   Reply With Quote Quick reply to this message
Unread 11-15-2013, 05:56 PM   #71
prubicon
Registered User
2000 TJ Wrangler 
 
Join Date: Dec 2009
Location: Lincoln, NE
Posts: 35
I don't even worry about gas mileage, I don't drive a jeep because it gets good gas mileage. I just drive it to enjoy it
prubicon is offline   Reply With Quote Quick reply to this message
Unread 01-08-2014, 08:18 AM   #72
91Cherokee7
Registered User
1991 XJ Cherokee 
 
Join Date: Dec 2013
Location: Streator, Illinois
Posts: 13
I was getting around 13mpg until i started using (Lucas upper cylinder lubricant its like a 24oz bottle, 3oz per 11gallons of gas) which increased my mpg to 17-19. A total of around 50 more miles on a full tank.The stuff works people and its only $11 at walmart, Autozone.
91Cherokee7 is offline   Reply With Quote Quick reply to this message
Unread 02-02-2014, 09:46 AM   #73
mudinmopar2000
Registered User
 
Join Date: Feb 2014
Posts: 1
Quote:
Originally Posted by 91Cherokee7 View Post
I was getting around 13mpg until i started using (Lucas upper cylinder lubricant its like a 24oz bottle, 3oz per 11gallons of gas) which increased my mpg to 17-19. A total of around 50 more miles on a full tank.The stuff works people and its only $11 at walmart, Autozone.
I have a 2000 jeep xj and I have the rustys off road k&n air filter kit. On the cold weeks I get about 18mpg and 22mpg when it's 60 or warmer. The kit is $130 but it was the best kit I have bought. I also have platinum plugs too and I run 87 with no ethanol. If u run hotter plugs with 87 it's better because you burn less fuel but the fuel that is in the cylinder is all burt because it's a hotter plug there for you get better mpg.
mudinmopar2000 is offline   Reply With Quote Quick reply to this message
Unread 02-02-2014, 10:36 AM   #74
222Doc
Web Wheeler
 
222Doc's Avatar
2012 JK Wrangler 
 
Join Date: Sep 2011
Location: Lake Havasu City, AZ
Posts: 4,883
So how does the plug change AFR? it can not. Hotter plugs tend cause detonation. its a matter of the right use.
__________________
http://www.parker4wheelers.net
www.bullhead4wheelersinc.com
222Doc is online now   Reply With Quote Quick reply to this message
Unread 02-03-2014, 10:17 AM   #75
dmj13
All Jeep'd up.
 
dmj13's Avatar
2006 LJ Wrangler 
 
Join Date: Jun 2012
Location: San Antonio, Texas
Posts: 182
I watched my mpg drop steadily over several months and could not figure out what was going on. I changed fluids, have iridium plugs and new wires, cleaned throttle body, replaced AIC and MAP sensor, O2 sensors all around- got barely any improvement. I had gone from 15-17 on the highway to 10 or less.
Finally, I had the TJ on a lift for some other work and noticed when I bumped the exhaust that I had major movement at the manifold/exhaust flange. I torqued the four bolts down to spec and have noticed an mpg improvement, although I will have to run a couple more tanks of gas to be sure.
My guess is the loose flange connection was allowing air to enter the exhaust before the front O2 sensors. More air would cause a false lean condition, which would cause the computer to adjust by dumping more fuel into the system and reducing mileage. I'm going to pull the plugs to see what they look like this week sometime.
Does my logic make sense? I didn't see a mention of pre-cat air leaks in this thread. Maybe something else for folks to check.
__________________
'06 Rubi LJ- 3" Currie springs, Bilstein 5100s, JKS links, BPEs, Metal Cloak TBs, ZJ tierod/ends, Monstalined, KC Fogs, 32" Firestone A/Ts, PowerStop brakes, R.E. adj. CAs, 2 dogs 'n a KCCO sticker.
dmj13 is offline   Reply With Quote Quick reply to this message
Reply

Tags
faq , gas mileage , improve mpg , miles per gallon , mpg , poor gas mileage

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.