poppster
Tell the truth and then run.
Premium
join:2003-12-23
Midwest
clubs: 
 ·Mediacom
|  [Help] 2004 Liberty question
My wife bought a 2004 Jeep Liberty Columbia Edition a couple of years ago, and it had decent mpg, not great, but decent.
Well now it's absolutely horrendous. What would cause such a decrease in mpg?
Too much ethanol in the gas?
Maybe she needs new spark plugs? I was thinking of getting some Champion double platinums, but I don't want to spend the cash if that won't help. It has 39,869 miles on it, and as far as I know the plugs have never been changed. I mean she burns 1/4 tank in about 22 miles.
Any help is much appreciated.
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psafux
Got Grep?
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join:2005-11-10
| according to fueleconomy.gov, that vehicle should be getting a combined (city & highway) mileage of 17 mpg. Shaving 20% to be fair brings it down to about 14 mpg.
Edmunds indicates your vehicle has a 19.5 gallon gas tank.
If my math is correct, you are getting less than 5 mpg if all the info provided is accurate.
How many miles are you getting in between fillups? that would be more reliable than looking at the fuel gauge as they aren't always reliable. I had a Blazer that would 'use' a ton of gas down to the 1/4 fuel mark and then it would sit there for 150 miles without moving.
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TheHarvester
Premium
join:2006-08-25
Dana Point, CA
| reply to poppster
Put whatever plugs the manufacture recommends. Don't waste the money on Platinum plugs if they do not call for them. Most Chrysler vehicles plugs are recommended every 30,000 miles.
Any check engine light? If mileage is that bad I would imagine it would set a rich code. If you have access to a scanner, take a look at the short and long term fuel trims and the O2 voltages.
Any signs of leaks anywhere?
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santy
Don't Follow Me, I'M Lost Too
Premium,MVM
join:2001-06-10
Wilmington, IL
clubs: | reply to poppster
I would also add check your air filter to what TheHarvester  said. |
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matt5
join:2001-10-06
Lagrangeville, NY
| reply to poppster
If you really are burning 1/4 a tank in 22 miles it has to be running stupidly rich. Any smoke out the tail pipe? I would also stop driving the vehicle you have to be causing damage to the cat using that much fuel. Have the fuel trim and o2 sensors checked. |
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joako
Premium
join:2000-09-07
/dev/null
1 edit | reply to poppster
Use OEM plugs or 100% equivalent (e.g. NGK you can buy from the dealer with the marque logo for $20 each or you can get the same plug with the same NGK # from Advance Auto, Amazon.com, etc for $5/ea.) |
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shawn01606
join:2004-08-01
USA | reply to poppster
With that motor use to OEM plugs (I believe they are NGK)...Plats do not work well at all with that motor at all. |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| said by shawn01606 :With that motor use to OEM plugs (I believe they are NGK).. Most Jeeps are Champion Spark Plugs from the Factory. If this is the standard 2.4L inline 4 then it calls for Copper Core Champions every 30K.
2004 : JEEP : LIBERTY : 2.4L 148 cubic inch L4 FI (1) : Ignition : Spark Plug
»www.rockauto.com/catalog/x,carco···ype,7212
CHAMPION Part # 443 {Copper Plus #RE16MC} OEM Spark Plug
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Waterbug
join:2008-03-30
| said by Doctor Olds :said by shawn01606 :With that motor use to OEM plugs (I believe they are NGK).. Most Jeeps are Champion Spark Plugs from the Factory. If this is the standard 2.4L inline 4 then it calls for Copper Core Champions every 30K. 2004 : JEEP : LIBERTY : 2.4L 148 cubic inch L4 FI (1) : Ignition : Spark Plug » www.rockauto.com/catalog/x,carco···ype,7212CHAMPION Part # 443 {Copper Plus #RE16MC} OEM Spark Plug That makes the liberty about 10,000 miles over the recommended plug replacement interval. I find it hard to believe that it comes with Copper Core Plugs in 2004. |
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matt5
join:2001-10-06
Lagrangeville, NY | They spelled Jeep wrong, they meant "Junk". Ya 30k is correct, I would think she run rough if the plugs are bad, but indeed if they are overdue it's step one. |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| 
Normal Plug showing no wear yet only light deposits | 
Worn Out Plug showing large gap increase and rounded electrodes from severe erosion |
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poppster
Tell the truth and then run.
Premium
join:2003-12-23
Midwest
clubs:
·Mediacom
| reply to Waterbug
said by Waterbug :said by Doctor Olds :said by shawn01606 :With that motor use to OEM plugs (I believe they are NGK).. Most Jeeps are Champion Spark Plugs from the Factory. If this is the standard 2.4L inline 4 then it calls for Copper Core Champions every 30K. 2004 : JEEP : LIBERTY : 2.4L 148 cubic inch L4 FI (1) : Ignition : Spark Plug » www.rockauto.com/catalog/x,carco···ype,7212CHAMPION Part # 443 {Copper Plus #RE16MC} OEM Spark Plug That makes the liberty about 10,000 miles over the recommended plug replacement interval. I find it hard to believe that it comes with Copper Core Plugs in 2004. It's a 3.7L V6 4WD.
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| said by poppster :It's a 3.7L V6 4WD. Double check the Underhood Emissions Sticker/Engine Specs Sticker or the Owners Manual for the OE Number for the plug.
It appears to still be a Champion Copper Plus Core as OE on these three Liberty's that have 3.7L 8th digit VIN "K" engines:
LIBERTY LIMITED
LIBERTY RENEGADE
LIBERTY SPORT.
2004 : JEEP : LIBERTY SPORT : 3.7L 226 cubic inch V6 FI (K) : Ignition : Spark Plug
»www.rockauto.com/catalog/x,carco···ype,7212
CHAMPION Part # 434 {Copper Plus #RC9MC4} OE Style {.035}
$1.68 each
Alternate OEM Part Number RC9MC4
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StNickless
@tmodns.net
 from:
3SGTE
| Umm....no.
If the spark plugs were such an issue as to cause LARGE drops in fuel mileage the vehicle would be mis-firing, badly.
Certainly it could probably use new ones, but that is an asthetic issue right now more than anything....a step, just not the right one.
The fuel pressure regulator...check the vac hose to it... is it wet inside from fuel getting by the diaphragm ?
If so, you just found the problem....change the fuel regulator.
If I'm not mistaken that vehicle has a vac hose to the MAP sensor...is it in good shape, not cracked, broken, or collapsed ?
If so...1$ will get you a new piece of hose and cure that problem.
It needs scanned by someone who knows how to read a live data scan.
Short term and long term fuel trims, injector pulse widths, MAP and engine load, O2 ranges....yadda yadda...you know...
It needs something more than spark plugs.
Never been a fan of Chisler...ahem...Chrysler engines, seen too many valve train issues, and that could be the problem here.
I've seen tons of them with tulip'd valves and broken valve springs and rocker supports, seen more than I'd want to of dropped valve seats too.
If I didn't have the skills I'd ask around for a solid reputation shop that would diagnose it for a minimal fee. I've worked in plenty of shops that would give an accurate diag for a standard 1 hour labor fee on something driveability like this (I should know, I've bitched about being paid 1 hour flag for doing it enough times). |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| said by StNickless :
Umm....no.
If the spark plugs were such an issue as to cause LARGE drops in fuel mileage the vehicle would be mis-firing, badly.
Certainly it could probably use new ones, but that is an asthetic issue right now more than anything....a step, just not the right one.
There is no way you know how the vehicle is running and it could very well be running badly and the OP may have not posted all the details of all the drivability issues other than the reduced MPG. The vehicle needs a 30K service that it is past due for (which includes the plugs, likely a PVC valve, air filter and oil change even though they were not the only required 30K services needed or suggested) and likely has been neglected since these basic services are past due 10K now, but lets just ignore the basics that need to be done anyway and do instead as you suggest (go on a wild goose chase instead while ignoring the minimum needs of the vehicle). I've never heard a 30K vehicle service called a reflection on art, culture and nature when it is simply the basics of required minimum maintenance, but whatever floats your boat. Minimum maintenance ignored as a display of art since plugged or dirty air filters, dirty oil and eroded spark plugs are just so aesthetically pleasing they should be left alone and admired, that's a new fud approach. 
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