Jeep Wrangler Forum

Jeep Wrangler Forum (http://www.wranglerforum.com/)
-   TJ General Discussion Forum (http://www.wranglerforum.com/f282/)
-   -   Getting 7 miles to the gallon? (http://www.wranglerforum.com/f282/getting-7-miles-to-the-gallon-183897.html)

BigDogs Graphics 08-30-2012 03:16 PM

Getting 7 miles to the gallon?
 
I have a '98 TJ and I am only getting 7 miles to the gallon. I have changed the spark plugs but I can not really tell a difference. If anyone has any suggestion please let me know!

Trevor C 08-30-2012 03:28 PM

What's the Tire size, is it a manual, what gears, and how much extra stuff do you have on it like a new bumper, winch, hardtop?

BigDogs Graphics 08-30-2012 03:33 PM

I am running a 31x10.50x15 BF Goodrich Mud Terrain Tire, It is a automatic 2.5L, Soft Top,

Trevor C 08-30-2012 03:34 PM

Stock gears?

BigDogs Graphics 08-30-2012 03:36 PM

Yes, stock as far as I know!

homebrwd 08-30-2012 03:37 PM

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

mickeygriffin 08-30-2012 03:40 PM

Ill stop complaining about my 10mpg....

Trevor C 08-30-2012 03:41 PM

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.

homebrwd 08-30-2012 03:43 PM

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.

56cj5 08-30-2012 03:59 PM

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??

Trevor C 08-30-2012 04:00 PM

What rpm does it idle?

zeprider25 08-30-2012 04:33 PM

showing this to my wife so she stops complaining about my 14mpg

scott howard 08-30-2012 07:15 PM

Quote:

Originally Posted by zeprider25 (Post 2741926)
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.

Rooster21 08-30-2012 07:56 PM

Quote:

Originally Posted by scott howard (Post 2742419)
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..

Riptide63 08-30-2012 09:04 PM

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.

harleydragon 08-30-2012 09:05 PM

check your exhaust also..stopped up cat converter kills power and gas mileage

jherrington 08-30-2012 09:11 PM

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.

Leeroy Jeepkins 08-30-2012 09:19 PM

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

Trevor C 08-30-2012 10:22 PM

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.

banks316 08-30-2012 10:39 PM

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.

tkagad 08-30-2012 11:21 PM

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.

div4gold 08-31-2012 12:26 AM

Quote:

Originally Posted by tkagad (Post 2743320)
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.

cork1958 08-31-2012 05:59 AM

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.

James249G 08-31-2012 08:02 AM

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!

banks316 08-31-2012 11:18 PM

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.

BigDogs Graphics 09-02-2012 10:02 PM

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.

Coastiejeep 09-02-2012 10:27 PM

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

BigDogs Graphics 09-02-2012 10:31 PM

No, speed is pretty much dead on with gauge.

SeVeReDiStOrTiOn 09-02-2012 11:34 PM

Quote:

Originally Posted by BigDogs Graphics (Post 2751690)
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?

97GreenGiant 09-03-2012 12:55 AM

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


All times are GMT -5. The time now is 11:45 PM.