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Unread 03-27-2013, 02:41 PM   #1
ChanWK
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2005 WK 
 
Join Date: Mar 2013
Location: Newton, MA
Posts: 101
9.5 MPG? How to improve?

Hey,
So I recently just bought my first car and first jeep and for some reason my fuel economy has been awful. I checked my trip computer and I'm getting 9.5 MPG... I have about 83500 miles on it wondering what I could do to fix it. I've been looking around and people are saying things from new spark plugs, O2 sensors, throttle body cleaner, and new spark plug wires. Any help would be great.

Thanks.

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Unread 03-27-2013, 04:05 PM   #2
Zlartibartfast
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Location: Menchaca, Texas
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first thing is - don't believe the readout from EVIC. It's probably low. Use pencil and paper calculations to measure your MPG's. Second thing is tire pressure. I got 1 more MPG by going from 33 to 38 PSI - really! Since it's new to you but has miles on it, I'd recommend a used oil analysis - it can help identify existing problems, and head off new ones.

If you're running a V6 then your mileage is too low, but if it's a big V8 then 10 MPG might be in the correct range for driving in city traffic.

"The most effective accessory to increase fuel economy is a tennis ball under the accelerator pedal" - G. W.
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Unread 03-27-2013, 04:37 PM   #3
jaje
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My neighbors WK Hemis get around 10 mpg in the city (where we live - lots of traffic lights) and around 18 mpg highway and mid teens combined. A lot has to do with driving style and looking ahead and try to get off the gas as early as possible when you will have to stop anyway and try to not stop unnecessarily.
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Unread 03-27-2013, 04:55 PM   #4
ChanWK
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Quote:
Originally Posted by Zlartibartfast View Post
first thing is - don't believe the readout from EVIC. It's probably low. Use pencil and paper calculations to measure your MPG's. Second thing is tire pressure. I got 1 more MPG by going from 33 to 38 PSI - really! Since it's new to you but has miles on it, I'd recommend a used oil analysis - it can help identify existing problems, and head off new ones.

If you're running a V6 then your mileage is too low, but if it's a big V8 then 10 MPG might be in the correct range for driving in city traffic.

"The most effective accessory to increase fuel economy is a tennis ball under the accelerator pedal" - G. W.
I have a hemi and was hoping to be getting 12-14 range. Where do you recommend getting one of these kits?
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Unread 03-27-2013, 04:58 PM   #5
wbrown85
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Spark plugs might not be a bad idea. Using some type of Hugh quality fuel system/injection cleaner would help. Your biggest thing.would definitely be driving style. Try not to accelerate so hard and coast a lot. If your in town that kills your mileage and if its still cold where you are that makes a huge difference.

One thing you definitely should NOT do is pump your tires up over 32 psi. You will get better mileage if you pump them up and it's very tempting to do but more air in the tires the faster you will chew through them. Tires inflated over the recommended pressure will over inflated them to where just the middle of the tire is contacting the road. So you will wear the middle out but not the edges. Plus your tires build up more pressure while you drive as well.
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Unread 03-27-2013, 08:51 PM   #6
BillyZim
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I could be wrong but I do remember reading that you should not use any spray throttle body cleaner on your wk. I do remember reading that it will cause damage.

My Hypertech programmer (part# 52501) gave me a gain of almost 2 mpg. It also improved acceleration. I readjusted my tire size with it too.
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Unread 03-27-2013, 09:33 PM   #7
ChanWK
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Yeah a friend suggested that to me but after reading around the forum realized that throttle body cleaner is not a good idea... Leaves me with only getting new spark plugs or spark plug wires or a new O2 sensor
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Unread 03-28-2013, 12:51 AM   #8
trax95008
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Quote:
Originally Posted by wbrown85
One thing you definitely should NOT do is pump your tires up over 32 psi.
Why are you telling people not to inflate over 32psi??? My door sticker says 35. Are you telling people to ignore their door sticker? And what if I had a heavy load in the back and needed a few more pounds to compensate??? I don't understand why your giving this advice...
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Unread 03-28-2013, 07:34 AM   #9
jaje
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I normally have the tires in my WK CRD at ~ 38 PSI on all 4 corners and will increase it to 40 PSI when towing & hauling race gear. The tires have an operating limit and can be filled over the OEM recommended especially when hauling / towing a heavy load. I got 17.9 mpg towing from KC to STL averaging 65 mph last weekend. Then on the way back with the snowstorm towed back and got 18.5 mpg doing an average of 50 mph.
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Unread 03-28-2013, 08:15 AM   #10
trax95008
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My point exactly 32 is too low
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Unread 03-28-2013, 08:19 AM   #11
Zlartibartfast
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re: used oil analysis - I get my kits from blackstone labs.

and don't forget about your air filter! when I was driving my ZJ with the straight 6, I gained about 1 MPG by upgrading to a K&N drop-in filter. Later I went to a cold air intake and got another 1.5 or so.

"your mileage may vary"

PS my tire pressure is now 34PSI @ 60F - they get up to about 38/39 after a warm up, & they feel just right. I did try them with about 42 PSI (warm) but it was a bit too bouncy.

When I ran my Jetta tires @ 45 PSI they did wear down the centers a bit, so I'm settling for 40 on that car. Rotation is just as important as proper pressure. Many drivers forget about this while their money goes right out the tail pipe
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Unread 03-28-2013, 09:23 AM   #12
wbrown85
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If the door says 35 psi then run it at spec. Over inflating the tires will result in chewing the tires up faster, unless you are pulling a trailer.
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Unread 03-28-2013, 09:38 AM   #13
trax95008
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Quote:
Originally Posted by wbrown85
If the door says 35 psi then run it at spec. Over inflating the tires will result in chewing the tires up faster, unless you are pulling a trailer.
Ok, that I agree with. I was just pointing out that you said not to exceed 32. And you don't necessarily have to be pulling a trailer to justify more air, even cargo in the back if heavy enough could call for more air
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Unread 03-28-2013, 11:05 AM   #14
IndyBlueWK
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My read out and what I do on paper are not to far off. I ve been going through a lot tying to cut weight, use the 89 gas, plugs, fuel system tune and I cant get any better MPG's.. The Hemi as I know it is a Fuel Sucking BEAST!
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Unread 03-28-2013, 05:41 PM   #15
ChanWK
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Waiting for my next fill up to calculations but my mpg just dropped to 9.3 and I've been going easy on the gas.
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