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Old 12-21-2010, 01:37 PM
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gas mileage? 4.0 what can i do?

Ok guys I just bought an 04 laredo. We love this vehicle it has barely 100k and runs and drives great. But this thing gets 14mpg. Which is not acceptable... I got several buddies that have them and are getting 20-21 on the highway and theirs has twice the miles. Mine has been very well kept looks like new. I am a mechanic and I have some pretty serious toys ranging from big blocks, turbo'd stang, modded powerstroke and this thing gets worse mileage than anything I own. I know chrysler products typically suck because they refuse to use a maf sensor. So let's put it out there... what are my options?...this is my first jeep so I don't know the market secrets yet to the jeeps.

Methanol injection
Turbo- got a few extras laying around
Programmer
Exhaust
Intake
Megasquirt standalone efi
4bt or hemi swap with custom tuning
Again this jeeps purpose is for trips and winter car for the wife. But from what I understand the 4.0 doesn't have the nuts to propel the weight of the vehicle and get mileage. Please shoot me some pointers guys and gals
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Old 12-21-2010, 06:27 PM
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Re: gas mileage? 4.0 what can i do?

I think your buddies might be the exception. Our '99 4.0 gets 15 city and maybe 19 highway if the winds blowing our way.The HO will out do it by 1 mpg city and 2 highway if I drive it like a rational human being. I'd try some synthetics,a good set of plugs(ie not Champion),clean the tb and maybe Superchips on the mileage tune. Also try a 185(not a 160) t stat as they run too warm on a 195. The stat seemed to help us.
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Old 12-22-2010, 03:36 AM
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Re: gas mileage? 4.0 what can i do?

Well ours is getting 14 on the road... the vehicle is driven 75mi a day just highway back and forth to work in 2wd. Comparatively speaking there are many other vehicles out there with similar build and weight getting much better mileage... my brothers expedition got 18 with 5.4 on the highway...I have seen 5.0 explorers knock down 20+.... I think someone needs to get these pigs on a dyno and try to do some serious r&d to achieve hp and mileage. who is the preimere custom tuner in the country for these jeeps? I am gonna research this more soon but I am puting in long hours now and again not trying to ruffle feathers guys but the "its a jeep" answer shouldn't cut it for having a mid sized suv that gets 14mpg. Thanks for the reply... is there a custom tuner available for sct or anything?... I've had superchips on my diesel and they are ok till u buy anything else custom...lol then they suck and u wonder why u ever even bought it.lol
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Old 12-22-2010, 05:51 AM
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Re: gas mileage? 4.0 what can i do?

You should be getting 18-21 on the highway. Maybe your not understanding get up to speed and cruise?
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Old 12-22-2010, 09:29 AM
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Re: gas mileage? 4.0 what can i do?

Damn, that mileage is TERRIBLE. This summer I took a trip from Indianapolis, IN to Columbus Ohio (nearly all interstate driving). I reset the computer overhead mpg thing (which I have verified to be correctt several times) when I was in the driveway and checked it again when I arrived. I got 26.4mpg with nearly all interstate at 80mph.

Driving 35 miles each way to and from work (I would say 35% city, 65% highway) I get an average of 21mpg. If I have only city driving there's a decrease and I get about 16-17 mpg.

If I was getting 14mpg on the highway, I would sell it and get another vehicle. To me, that's unacceptable. You might try running seafoam through the engine to clean any deposites. Also check standard things like clean air filter, are you cats clogged, clean throttle body, check your plugs, check your injectors, etc.
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Old 12-22-2010, 12:05 PM
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Re: gas mileage? 4.0 what can i do?

I have no 4.0, but my car suddenly started to use more fuel than it was used to. There was also some lack of power at certain throttle positions. After changing the fuel filter/pressure regulator this was all solved and gas milage back to normal (at least for this type of car) again.
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Old 12-22-2010, 12:48 PM
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Re: gas mileage? 4.0 what can i do?

Your kidding me right? The 4.0L isn't meant to be the strongest engine FYI. If you really want to do something to it get a 4.6L or 4.7L stroker kit for it and then build on top of that. I was going to do this 04' WJ, but I sold it to get my WK.
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Old 12-22-2010, 08:22 PM
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Re: gas mileage? 4.0 what can i do?

I would def. check the o2's and do seafoam
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Old 12-24-2010, 09:08 PM
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Re: gas mileage? 4.0 what can i do?

Thanks guys that's more like it...I love the vehicle. We bought it over a 2001 explorer 5.0... it is twice the vehicle but this mileage is horrible. What plugs are u guys running?... I have been wanting to try e3 plugs, cold air intake, or a k&n with a ported air box, and a programmer... the wife dumped 150 in the tank this week and I am pissed. My powerstroke will pull a damn house down and $150 will take u well over 1,000 miles. Give me ur mod list to try... I am willing to sink some cash in it to get some mileage but if its gonna be a money pit soaking up 8-10% of my weekly check every week I'll unload it. And no offense to the 3.7 or 4.7.... but I don't like them. I would rather do a 5.7 hemi swap or cummins 4bt swap... if it is hp to weight ratio. I have a feeling the 4.0 is capable of alot.
Has anyone tried hydrogen generators?
Methanol injection?
Turbo?
Sct or custom tunes?
Certain sized tires?
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Old 12-24-2010, 09:16 PM
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Re: gas mileage? 4.0 what can i do?

Oh and my wife drives all highway except 2 miles a day or house and her work are both a mile from the interstate... so its safe to say the mileage is piss poor. I filled it up she drove 245miles and filled up and it took 17.5 gallons which is 14mpg... that's insanity. Keep me posted on your mod lists.
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Old 12-24-2010, 09:34 PM
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Re: gas mileage? 4.0 what can i do?

I think the reason of your bad gas mileage is due to the winter blend gas. I'm having the same issues with my Liberty. Just check out my gas mileage in my sig
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Old 12-24-2010, 10:26 PM
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Re: gas mileage? 4.0 what can i do?

Oh and we only run 93 octane gas... its easier that way... I have some high strung toys and they always get better mileage burning the premium fuel
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