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-   -   Full tune-up HELP (http://www.jeepforum.com/forum/f13/full-tune-up-help-892853/)

BHand89 11-02-2009 11:42 PM

Full tune-up HELP
 
Hey guys, my WJ has been sorta sluggish since I got it and I think it needs a tune-up. I'm only getting 11mpg around town. What do you guys recommend? I've never done a tune-up to a Jeep before, I'm used to small block chevy's haha. What kind of plugs, wires, etc should I run? Thanks in advance

WiCkeDuDe 11-02-2009 11:45 PM

Run the factory champion plugs, you wont find any wires :)
I usually clean the IAC, plugs, fuel filter, and fluids.

straty1987 11-02-2009 11:59 PM

Jeep Grand Cherokee WJ - Maintenance information and schedules

check the list out and see if anything needs to done with the mileage you are at, its the recommended service intervals.

plugs is a good place to start, air filter, belt, fluids in diff and TC, transmission filter can be taken care of with as well as the engine oil.

as far as the 11 MPG goes, try changing your driving habits and cheeking you tiers PSI's. it helped me gain a few MPG's but its a jeep and i am fine with the 11 to 13 city range i get.

sandman 11-03-2009 02:36 AM

every year before winter hits i do a tune up on my jeep, this year i decided to go all out and ordered a performance tune up kit from summit that included summit cap and rotor, summit wires, accell performance coil and e3 spark plugs. it was a good deal plus i had a $20 off coupon that i had to use before the end of October. i bought a bunch of other stuff but if i remember right the tune up kit was less than $100.

http://i48.photobucket.com/albums/f2...3/DSC02176.jpg

Mopargearhead 11-03-2009 03:05 AM

Quote:

Originally Posted by WiCkeDuDe (Post 8220497)
Run the factory champion plugs, you wont find any wires :)
I usually clean the IAC, plugs, fuel filter, and fluids.

Ditto.The 4.7L doesn't have any plug wires. Each cylinder has its own coil.

WiCkeDuDe 11-03-2009 04:13 AM

Quote:

Originally Posted by Mopargearhead (Post 8220981)
Ditto.The 4.7L doesn't have any plug wires. Each cylinder has its own coil.

Yes this is true but the OP has a WJ which means the 4.0 has the coil pack rail thus it has no wires either.

Double E 11-03-2009 12:29 PM

Actually he has the 4.7L V8 ....but still no rotor, cap or wires as Sandman suggests.

+1 on a clean out of the throttle body. It's really easy and effective. Remove the vacuum hoses, remove the throttle cable, remove the IAC valve and take out 3? bolts. Clean it up & replace.

+1 on tire pressure. Consider an alignment too. They're both good for increasing mileage.

Also clean up your battery terminals to ensure a good connection. These things are so sensitive to inadequate battery voltage/amperage.

Toss in a bottle or 2 of Techron and...

THEN try really hard to keep your RPM down to 2K around town and when accelerating from stop and you'll see the mileage go up some. If you're doing highway miles, you might also consider getting the tranny flash that takes advantage of what is commonly referred to here as 5th gear. It will drop final drive gear RPM by about 350 RPM.

KDog223 11-03-2009 12:45 PM

Quote:

Originally Posted by Double E (Post 8222721)
If you're doing highway miles, you might also consider getting the tranny flash that takes advantage of what is commonly referred to here as 5th gear. It will drop final drive gear RPM by about 350 RPM.

Can you elaborate on that? Is this something a dealership performs?

sandman 11-03-2009 08:18 PM

sorry guys, im in my own little ZJ world over here.

Double E 11-04-2009 11:33 AM

Elaboration here: http://www.jeepforum.com/forum/f13/t...-trans-811851/

Explanation and links to the instructions for the dealer to refllash the tranny are towards the bottom of that post.

rm2001wj 11-04-2009 12:37 PM

The flash converts a 45RFE to a 545RFE. The 4th gear (first OD) ratio in both is 0.75. With the flash on a 45RFE, you get a 2nd OD with a final ratio of 0.67. That is a 10% drop in gear ratios which gives a 10% drop in rpms when shifting from 4th to 5th. Do the math and that says 2200 rpm in 4th becomes 2000 rpm in 5th. A 350-400 rpm drop is a little too optimistic.

Double E 11-05-2009 11:32 AM

Got me. I'm an optimist!


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