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04 wj mpg

9K views 32 replies 9 participants last post by  mrjaydeeone 
#1 ·
Just wondering those of you with WJ's with a 4.0 what are you getting mpgwise?
I got mine back the start of the year. I am currently at 123,200 miles. Since I have gotten it I have fluctated between 15.8 and 15.9 mph. That's through the winter temps and the summer ones. No increase driving on highway for a decent length trip either.
What kinda mileage are the rest of yous getting?
what can I do to improve this?
 
#3 ·
good idea. I think I will change the plugs. Think I should do the wires also? I don't believe any of that has been changed in my WJ before I got it. Also what kinda plugs and wires are best to use here.
I am looking at wjjeeps.com to get an idea of the plug change on here. Seems like it's pretty easy. Is that the case? I have changed them in my galants before and those were inline 4s.
 
#4 ·
You don't have any wires. You have a Coil Pack. IMO I would just get the Factory Spec Spark Plugs. When you Open the Hood underneath the actual hood, you will see a specification for what type of spark plugs. It might be on www.WJJeeps.com And make sure you have the right extensions, especially for the last spark plug! And make sure you get them all gapped before you install them!
 
#18 ·
You don't have any wires. You have a Coil Pack. IMO I would just get the Factory Spec Spark Plugs. When you Open the Hood underneath the actual hood, you will see a specification for what type of spark plugs. It might be on www.WJJeeps.com And make sure you have the right extensions, especially for the last spark plug! And make sure you get them all gapped before you install them!
I checked under the hood at the sticker and it says Rc12mcc4 gap .040
and when I looked back on wjjeeps.com it shows that for a 4.7. I only have a 4.0.
Now I am a bit confused. Could the plugs and gap be wrong in my Jeep? Could the hood have just been replaced at somepoint with a used one?
 
#5 ·
okay gotcha gotcha thank you for your help. Would I want to replace the coil pack while I am at it? or leave it alone unless it needed to be replaced?
 
#7 ·
yeah I got there afterwards haha. thanks bud
 
#12 ·
well I looked at the maintenance records from the previous owner. The plugs were changed by the dealer in March of 07 at 91k. They shouldn't need to be replaced yet, right?
also I was told that I should replace all the 02 sensors. 1 was replaced a few months back when I got a CEL. Should I replace the rest?
 
#16 ·
spark plugs on the WJ 4.0 or 4.7 should be changed at 30,000 miles
your at 123,200 so your a bit past 30K
decent info hear on the how to http://wjjeeps.com/service/sparkplugs.htm
and you have a inline so dont have to reach to far back

also might want to do the diff and TC fluid since it may need it. if the fluid is worn out could effect MPG as well

i just changed mine on the 4.7 last Thursday at 42K+ and they were the orignals and were over gaped and needed them. will see if it helps my MPG which is normally can be from 10-16 MPG depending on what i am doing, carrying a load or taking a long trip.

yeah 25 hwy its a selec-trac went to jersey last week about a 75 mile trip and thats what it read on mileage that was also going only 60 the whole time but it's true
unless you did the math i think its a bit high.
since jeep could only get 21 MPG highway with 2WD when they tested and they try to push the limited on what they can get.
 
#14 ·
I learned this actually a when I got the CEL. I got an aftermarket one and immediately the CEL came back. I ordered an OEM one from Kolak, which was actually cheaper then the aftermarket (go figure) and have had no problems since
 
#20 ·
not that I know of. I honestly doubt that it would have. I need to look at the sticker again and see if it says 4.7 on it anywhere too.
 
#22 ·
LOL. I sent him Milous a PM to take a look at this thread
 
#32 ·
LOL. I am just curious now. I looked at the sticker again and it's from a 4.7. Should there be a sticker with the vin under the hood?
 
#33 ·
changed the plugs the other day. I picked up some autolite platinums. I removed
Ngk r zfr5n. One looked worse then the one before it, I will take and post pics of them. Let's see if that helps any.
 
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