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Unread 11-02-2009, 10:42 PM   #1
BHand89
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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

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Unread 11-02-2009, 10:45 PM   #2
WiCkeDuDe
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Run the factory champion plugs, you wont find any wires
I usually clean the IAC, plugs, fuel filter, and fluids.
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Unread 11-02-2009, 10:59 PM   #3
straty1987
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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.
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Unread 11-03-2009, 01:36 AM   #4
sandman
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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.

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Unread 11-03-2009, 02:05 AM   #5
Mopargearhead
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Quote:
Originally Posted by WiCkeDuDe View Post
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.
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Unread 11-03-2009, 03:13 AM   #6
WiCkeDuDe
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Quote:
Originally Posted by Mopargearhead View Post
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.
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Unread 11-03-2009, 11:29 AM   #7
Double E
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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.
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Changes & fixes: Rear Addco sway bar & greasble bushings, upgraded headlights, upgraded tail lights, new hood struts (replaced 2X), new rear hatchglass struts, new radiator (replaced 3X), new oil pressure sending unit (replaced 4X), 2 new speed sensors, 2 new door lock actuators, new ignition key cylinder, chrome front tow hooks, Mobil 1 Synthetic 5/30, Purolator Pure One oil filter, EBC slotted & dimpled rotors, EBC Greenstuff pads, new front shocks (replaced 3X), new rear shocks (replaced 2X), new IRO steering stabilizer, new timing chain cover, new water pump, thermostat, new thermostat housing, new high pressure power steering hose, Michelin-X radials, new sunroof assembly, new single-piece lug nuts, new exhaust manifold studs & gasket on driver's side, new Durango alternator. Jeepforum.com sticker, Visit cobaltboatsforum.com when you can!
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Unread 11-03-2009, 11:45 AM   #8
KDog223
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Quote:
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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?
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Unread 11-03-2009, 07:18 PM   #9
sandman
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sorry guys, im in my own little ZJ world over here.
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Unread 11-04-2009, 10:33 AM   #10
Double E
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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.
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2000 Laredo 4.7L Selec-Trac. 177K miles, Leather, 245 tires, tow package, crappy CD changer, full size spare, roof cross-rails & sunroof.
Changes & fixes: Rear Addco sway bar & greasble bushings, upgraded headlights, upgraded tail lights, new hood struts (replaced 2X), new rear hatchglass struts, new radiator (replaced 3X), new oil pressure sending unit (replaced 4X), 2 new speed sensors, 2 new door lock actuators, new ignition key cylinder, chrome front tow hooks, Mobil 1 Synthetic 5/30, Purolator Pure One oil filter, EBC slotted & dimpled rotors, EBC Greenstuff pads, new front shocks (replaced 3X), new rear shocks (replaced 2X), new IRO steering stabilizer, new timing chain cover, new water pump, thermostat, new thermostat housing, new high pressure power steering hose, Michelin-X radials, new sunroof assembly, new single-piece lug nuts, new exhaust manifold studs & gasket on driver's side, new Durango alternator. Jeepforum.com sticker, Visit cobaltboatsforum.com when you can!
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Unread 11-04-2009, 11:37 AM   #11
rm2001wj
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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.
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Unread 11-05-2009, 10:32 AM   #12
Double E
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Got me. I'm an optimist!
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2000 Laredo 4.7L Selec-Trac. 177K miles, Leather, 245 tires, tow package, crappy CD changer, full size spare, roof cross-rails & sunroof.
Changes & fixes: Rear Addco sway bar & greasble bushings, upgraded headlights, upgraded tail lights, new hood struts (replaced 2X), new rear hatchglass struts, new radiator (replaced 3X), new oil pressure sending unit (replaced 4X), 2 new speed sensors, 2 new door lock actuators, new ignition key cylinder, chrome front tow hooks, Mobil 1 Synthetic 5/30, Purolator Pure One oil filter, EBC slotted & dimpled rotors, EBC Greenstuff pads, new front shocks (replaced 3X), new rear shocks (replaced 2X), new IRO steering stabilizer, new timing chain cover, new water pump, thermostat, new thermostat housing, new high pressure power steering hose, Michelin-X radials, new sunroof assembly, new single-piece lug nuts, new exhaust manifold studs & gasket on driver's side, new Durango alternator. Jeepforum.com sticker, Visit cobaltboatsforum.com when you can!
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