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Topic Review (Newest First)
09-03-2012 07:19 PM
ballistx
distance

Another thing is how far do you drive each trip. If it never gets warmed up it will give worse mileage. Could be a combination of a lot of things. Make a list of the things that effect mileage and then do a yes/no and see how it fares. Correct all that are no and are reasonable to correct. See how it checks out then.

make sure it isn't lugging. You said automatic. If it is not down shifting properly it is going to be lugging the engine and that will burn more fuel. The 2.5 needs to be in the 1500+ range to get efficient torque.
09-03-2012 07:07 PM
Gaducker
Quote:
Originally Posted by gmabry75 View Post
You get 28 mpg in what?


That scrambler in the avatar.
09-03-2012 05:08 PM
gmabry75
Quote:
Originally Posted by Gaducker
I get twenty eight mpg in town. per gps
You get 28 mpg in what?
09-03-2012 04:52 PM
Gaducker I get twenty eight mpg in town. per gps
09-03-2012 08:28 AM
ou812 My 4.0 has almost a quarter million miles on the stock engine and i was getting 8-10 mph
I changed my timing chain and sprockets and I'm back to 14-16 mpg
Plus more noticeable power
09-02-2012 11:55 PM
97GreenGiant Have advance read your obd2 my guess in O2 sensors by chip he means a performance chip that can change your air to fuel rating in your intake mani but will only give you like 3 to 5 mpg for around 3 or 4 hundred dollars
09-02-2012 10:34 PM
SeVeReDiStOrTiOn
Quote:
Originally Posted by BigDogs Graphics View Post
I had the jeep checkout Saturday and the mechanic found nothing wrong with cat. converter. He said the timing could us to be adjusted but when he referred to some online material it said it was not adjustable. He also recommend an emissions chip in order to straighten out the timing and gas mileage. What do you all thing about his recommendations?

Thanks,
Corey V.
Emissions chip? WTF is that? If he's talking about a tune, no tune in the world is going to fix your 7 mpg problem. If I was you i'd clean EVERYTHING (throttle body, PCV, run seafoam through the top-end and in the tank) and do a full tune up (oil, diffs, tranny,all filters). I'd also take the brakes apart and clean/lube them incase you have a sticking guide pin. Do you feel any excess drag?
09-02-2012 09:31 PM
BigDogs Graphics No, speed is pretty much dead on with gauge.
09-02-2012 09:27 PM
Coastiejeep Did the speedo gear get changed? with the larger tire size it will not read right. for an example it says your going 65 and really going 72. that will throw off your calc for mpg and your odometer. hope that helps
09-02-2012 09:02 PM
BigDogs Graphics I had the jeep checkout Saturday and the mechanic found nothing wrong with cat. converter. He said the timing could us to be adjusted but when he referred to some online material it said it was not adjustable. He also recommend an emissions chip in order to straighten out the timing and gas mileage. What do you all thing about his recommendations?

Thanks,
Corey V.
08-31-2012 10:18 PM
banks316 Im running a 4.7L stroker, 4.56 gears with 37s and im getting 14mpg (confirmed by GPS)on top of all that with all my armor and gear i drive around with im pushing 4800lbs my jeep is a tank.
08-31-2012 07:02 AM
James249G 2004 TJ, 33x12.5 Mud Terrains on 15" Wheels, 4" Suspension Lift, Stock bumbers (minus the milk jugs), 5speed Manual... I'm averaging 7 - 10 MPG as per my GPS. Maybe I'll just buy a Jeep Compass!
08-31-2012 04:59 AM
cork1958 Yeah,
I'd say it was you cat converter also. Just about no doubt in my mind. As plugged as yours might be, it is probably glowing red when driving! Was on my plugged up cat on my truck.

Cripe! 7 mpg's makes my '66 Plymouth Satellite look awesome!! Even my Jeep get's better than that car! I get about 18-20 with a 5 speed manual and a 4.0L in Jeep.
08-30-2012 11:26 PM
div4gold
Quote:
Originally Posted by tkagad View Post
You might have a bad cat converter. I had a very similar issue. I changed the spark plugs and cleaned the throttle body, which made a minor difference, but when I replaced my clogged cat, my MPG jumped up by like 8.
I'm of the same mind, if it seems to be running decent and just getting crappy mileage I think the exhaust is plugged up, cat.
08-30-2012 10:21 PM
tkagad You might have a bad cat converter. I had a very similar issue. I changed the spark plugs and cleaned the throttle body, which made a minor difference, but when I replaced my clogged cat, my MPG jumped up by like 8.
08-30-2012 09:39 PM
banks316 First off how are you measuring your fuel usage? Odometer or GPS?

If odometer is your spedo correct? If its off by just a few mph it will throw off your odometer thus giving you false numbers

Have you replaced your O2 sensors? If it fails the ECU thinks your running lean and burns more fuel to try to get to optimal mixure.

Is your header cracked? If so you suck in air confusing your O2 sensor making it think your running lean then telling the ECU to dump more fuel.

What temp is your engine running? Below 210 the ECU thinks the engine is cold and will burn more fuel to try to get engine up to operating temp.

What weight oil you running? Too think and your engine has to work harder to pump it.

Air filter have you changed it/cleaned it lately?

Cap/rotor when was the last time you changed that? Corroded thermals can cause misfires

Spark plug wires? Worn wire can cause drop in resistance which in turns causes spark plugs from working to peak perfermance.

Spark plug whats the gaping at? Should be .035

Thats all I got for now.
08-30-2012 09:22 PM
Trevor C
Quote:
Originally Posted by Leeroy Jeepkins
get bigger tires,add racing stripes on the sides and cram a potato in the tailpipe.it can't be any potato though it has to be an Idaho potato. you should see a huge difference in MPG.

it might be more or less.....prolly less
One of my friends did this, and it worked awesomely! But he didn't use a potato he used a Georgia peach.
08-30-2012 08:19 PM
Leeroy Jeepkins get bigger tires,add racing stripes on the sides and cram a potato in the tailpipe.it can't be any potato though it has to be an Idaho potato. you should see a huge difference in MPG.

















































it might be more or less.....prolly less
08-30-2012 08:11 PM
jherrington keep rpms below the 2k mark. drive without air conditioner. i used to get 22 before i got the AC fixed and got an after market radio, and a new bumper, now i get 17.
08-30-2012 08:05 PM
harleydragon check your exhaust also..stopped up cat converter kills power and gas mileage
08-30-2012 08:04 PM
Riptide63 Wow! You'd think if it was running that poorly the check engine light would be glowing in the dash. The 2000 2.5 5-speed I previously owned got 17 with 32" mudders and 19 with 30" street tires, but from what I see here in comparison mine was some kind of freak. Probably wouldn't hurt to have someone plug into it with a scanner. Something isn't right.
08-30-2012 06:56 PM
Rooster21
Quote:
Originally Posted by scott howard View Post
I showed my wife to too but she said her
It should get around 15 or better.
That is what I average with 31x10.5 in my 97 2.5 auto... That is running a/c with Hardtop..
08-30-2012 06:15 PM
scott howard
Quote:
Originally Posted by zeprider25 View Post
showing this to my wife so she stops complaining about my 14mpg
I showed my wife to too but she said her Samurai gets 30mpg so i still need to get a second job to pay for my gas...lol

Check your air filter and check all your vacuum lines for leaks.
do a compression test to make sure your motor is in good shape.
It should get around 15 or better.

If none of this helps plan your trips with lots of down hill roads and coast.
08-30-2012 03:33 PM
zeprider25 showing this to my wife so she stops complaining about my 14mpg
08-30-2012 03:00 PM
Trevor C What rpm does it idle?
08-30-2012 02:59 PM
56cj5 Driving style has alot to do with MPGs. Do you drive like an old lady to church on Sunday ??? Or a teenager who "borrowed". His dads corvette??
08-30-2012 02:43 PM
homebrwd Along with my previous list, when was the last time your diffs, transfer case and transmission were serviced? Friction in those locations wont help either.
08-30-2012 02:41 PM
Trevor C Well it shouldn't make a big difference, you only have 31s, I guess wait til someone else that has more experience. I have 2.5 with 35s and I get about 15 a gallon.
08-30-2012 02:40 PM
mickeygriffin Ill stop complaining about my 10mpg....
08-30-2012 02:37 PM
homebrwd Oil change, spark plugs, clean throttle body, air filter, distributor cap cleaning/replacement, spark plug wires?

TK-16 - Crown Tune-Up Kit for 97-98 Jeep® Wrangler TJ with 2.5L 4 Cylinder Engine - Quadratec
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