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Old 12-12-2007, 09:06 PM   #1
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4 Banger Gobbles Fuel

So as soon as the cold weather really set in my 4 banger's fuel economy plunged...from 20.5 mpg to 13-14 ish. Here's the facts; 2000 2.5 L, new alt, new belt. Has a wobbly idle (leaky head gasket?) and the cooling system is filthy. It heats up just fine, I only have to drive around the block and it heats up to 210. I'm going to change the plugs this weekend and get the radiator flushed.

Any other suggestions?

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Old 12-12-2007, 10:55 PM   #2
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Is your check engine light on? a bad O2 sensor maybe?

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Old 12-13-2007, 11:59 AM   #3
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OIL, change the oil. if your going as far as doing the rad flush and sparks just do the whole tune up. oil, dist cap/rotor, plugs, wires. that should improve your milege... oh and Just FYI the wrangler usually runs about 210 in temp, so flush the rad if you want but I don't think you really need it.
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Old 12-13-2007, 03:07 PM   #4
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Also, consider that some areas switch to a winter type blend and that blend may affect your mileage.
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Old 12-13-2007, 07:39 PM   #5
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Alot of things have effect on gas mileage... In the cold oil gets thick and reduces gas mileage...could be part of the problem but it certainly wouldnt drop the mileage that much. Maybe check your O2 sensor and replace it if it needs it. Air filter could also be clogged. Have you driven it in 4wd at all lately? Using 4wd reduces your mileage dramaticly. Check your tire pressure too.
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Old 12-15-2007, 12:27 AM   #6
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I just changed the oil a couple of hundred miles back. Check engine light is not on, has never come on.

The coolant is rusty brown with a sludge on the bottom of the reservoir. I emptied it a couple of weeks back, rinsed the reservoir out really good and refilled it with fresh coolant. Checked it the other day and its back to sludgy rusty brown.

I'll check out the the o2 sensor, hadn't thought of that. I'll look into the distributor and wires too. Might as well, my Christmas present to myself is refurbishing the Jeep. I'll be buying a new soft top for it later this month
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Old 12-15-2007, 01:15 AM   #7
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Ima freakin expert on bad head gaskets unfortunately.
Look for air bubbles in the radiator expansion tank, oil in the coolant and coolant in the oil.
Not likely to cause bad fuel economy too much though.
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Old 12-15-2007, 07:30 AM   #8
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Cold weather does have a huge effect on gas milage. I have lived in North Dakota all my life and once winter hits where the temps are below freezing everyday, gas milage takes a huge hit. It doesn't matter what type of car you have, its going to take more gas in the cold weather. Every vehical i have owned in my life ( which has been alot) has taken alot more fuel in the winter. Often times dropping the milage by 5,6, 7 miles per gallon, all depends on your driving style and what type of driving you do. Being that your in Maine your weather i assume is similar to mine in ND. Only i think you get alot more snow and we get alot more cold. Often times we get to -20 degrees for several days at a time. You can have your 02 sensor checked but my guess is it will check out just fine, and its just the fact that the temp is cold.
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Old 12-15-2007, 07:37 AM   #9
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I think Bush and his oil tycoons are secretly adding something to the gas to give everybody poor gas milage so he can get richer. I haven't noticed a difference in mpg with the colder weather because it a pig on gas no matter what the weather is. If I cared about the mpg, I'd get a Honda Civic with a coffee can exhaust.
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Old 12-15-2007, 10:30 AM   #10
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Cold air means more dense air. More dense air means more fuel being added by your computer based on fuel to air ratio. Therefore, cold air = more fuel used. But it also means better HP and Torque
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Old 12-15-2007, 06:18 PM   #11
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Quote:
Originally Posted by Smeghead View Post
Ima freakin expert on bad head gaskets unfortunately.
Look for air bubbles in the radiator expansion tank, oil in the coolant and coolant in the oil.
Not likely to cause bad fuel economy too much though.
Good to know, sorry you had to find out the hard way!
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Old 12-15-2007, 06:25 PM   #12
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I think Bush and his oil tycoons are secretly adding something to the gas to give everybody poor gas milage so he can get richer. I haven't noticed a difference in mpg with the colder weather because it a pig on gas no matter what the weather is. If I cared about the mpg, I'd get a Honda Civic with a coffee can exhaust.
Truer words were never said! All of it! Mileage be damned! I drive two, count 'em two 4WD vehicles! I also drive a Chevy 2500HD and that gets 12mpg, winter, summer, in 4Low, 4 High, plowing, towing or hauling groceries. 12mpg no matter what. I'll keep the Jeep over the Jetta I traded it for any day of the week and 69 times on Sunday.
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Old 12-16-2007, 05:57 PM   #13
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Run A Can Of Lucas Gas&top End Lub. Every Two Or Three Tanks Seems To Help With My Mileage. 2.5 5 Speed Manual. But Tune Up Is No. 1. Good Luck.
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Old 12-16-2007, 07:04 PM   #14
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Merry CHRISTmas!!
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Old 12-16-2007, 11:00 PM   #15
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Happy Holidays!!!
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Old 12-24-2007, 08:48 PM   #16
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So I just changed the spark plugs and damn what a difference! It immediately drove stronger, better acceleration and less noise. Cylinder #3's plug was really cruddy, white/gray deposits on the front of the plug. Give it a few weeks and I'll leave an update on how the fuel economy is doing.
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Old 12-24-2007, 09:33 PM   #17
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Quote:
Originally Posted by Walkeraviator View Post
Cold air means more dense air. More dense air means more fuel being added by your computer based on fuel to air ratio. Therefore, cold air = more fuel used. But it also means better HP and Torque
forgot to mention waiting 5 minutes every mourning for the engine to warm up = 0mpg...
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Old 02-02-2008, 03:55 PM   #18
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She's back up to 19 mpg from 14 mpg a month or so ago! That's mixed 4wd/highway driving in a variety of temperatures, -20 to + 35 degrees. I'm very pleased! Once summer gets here I hope to be getting 20+ mpg.

FYI: The modifications were new spark plugs and Castrol GTX 5w30 + a quart of lucas oil stabilizer.
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Old 02-02-2008, 03:59 PM   #19
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Quote:
Originally Posted by MaineJeeper View Post
white/gray deposits on the front of the plug

You burning any coolant?
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Old 02-02-2008, 04:15 PM   #20
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The coolant is filthy cruddy rusty red, with sludge in the overflow container.

But I never seem to lose any. This spring I'm going take off the radiator, back flush the whole system, replace the thermostat,then fill it back up with water and some kind of voodoo juice to help reseal the valve. Don't know what kind of voodoo goo to use yet. BTW voodoo juice is my monicker for any gimmicky fluid additive that promises to basically rebuild your whole jeep for pennies.
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Old 02-02-2008, 05:41 PM   #21
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INstead of doing that you might want to try this. First drain the radiator and fill it up with tap water. Next try this.. Some one made a flush system.. they took a garden hose and a 1-2" long hose (same diameter as the coolant hose) and at last a T pipe that has the 2 intlets across from eachother to fit the coolant hoses and the last one to fit the garden hose. They unhooked the top coolant hose and there they put the one end of the T in that hose, then the 1-2" long hose went on the other end of the T pipe and then connected to the radiator and at last the garden water hose went in the 3rd small end of the T pipe. Simply turn on the water and then open the radiator drain plug on the bottom to drain the water. At at last when you make sure everything is clear from the fans turn on the engine so you're circulating the coolant and mixing it with the clean water and its also draining at the same time. At first coolant will flow down and on the floor but make sure you have a drain somewhere so it goes right onto the drain instead of all over the driveway. Turn on the heater inside your jeep so it circulates the clean water through that too. Let it run for a bit of time and when you start seeing clean water flowing out of the radiator drain plug then stop the engine and shut off the water and the radiator drain plug. Empty the radiator and close the drain plug and then fill it up with the mixture of coolant and distilled water. At last clean the area under the car and to the drain of your driveway or garage or whatever.

Clear T pipe helps a lot so you can see whats going on in there. If no clear T pipe then use clear 1-2" long hose.

After you fill it all back up with the correct mixture run the heater for few minutes to get coolant in there too.

GGRRR i cant find the writeup since it had nice pictures too.
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Old 02-02-2008, 10:58 PM   #22
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I already bought a t connector to flush the cooling system with. Thanks for the writeup, I wouldn't have known to run the heat to get the water into the heater core. Check out my other thread I just posted about the vacuum issues, I could really use some advice on that.
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Old 02-03-2008, 11:54 AM   #23
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I havent even run thru a full tank of fuel yet but Im loving it so far. My 1500 Ram got 11 MPG w/ the Hemi. Drive it like an old lady and maybe get 12. So I drove it like I thought I should.

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