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Spark plugs and plug wires and tune ups oh my!

17K views 15 replies 10 participants last post by  Neil F. 
#1 ·
I'm a first time Jeep owner and this will be my first ever attempted tune up....
So here we go,I have a 98 TJ with the 4.0 and its got over 170k miles i wont lie the po beat on this jeep worse than bobby beat whitney:banghead:
so im trying to save the old girl peice at a time.... So what are the best plugs, plug wires, and whatever else you would recommend for a basic tune up to get me started? I'm no mechanic but im not afraid to try/ break anything once
 
#2 ·
OEM replacement. The engine was designed to run with those, and the parts are spec'd for the engine. Plugs, wires, cap and rotor, maybe a coil, carb & choke cleaner for the intake, and a can of BG44 in the tank.
 
#4 ·
A very good spark plug for your Jeep's 4.0L engine that will easily go 100K miles is the Autolite AP985. It has an erosion-resistant coating on the side of the gap that normally wears so it will continue to run well for at least 100K miles.

For the distributor cap and rotor, look for replacements that have their contacts made from brass. Cheap replacements use aluminum which wears faster.

For the ignition wires, you can't beat (really) the OE wires right from the dealer. Yes. It's so hard to find good quality ignition wires at the auto parts store because too many of them are shoddily made with all kinds of hyped up claims about adding performance. Many tout "low resistance" which is not good. Yes "low resistance" sounds good but in the case of ignition wiring, it's not. Standard wiring has very low resistance and would be cheaper to use but resistance is actually added at significant cost to ignition wiring.

The resistance is needed in ignition wiring to cut down on spark plug noise and static which can interfere with the engine computer and cause your AM radio to pick up static from the ignition wires if they don't have the required resistance. No, the added resistance doesn't significantly reduce the spark voltage due to the extremely small amount of current (micro-amperes) passing through the wires. Ohm's Law and all that. :)
 
#5 ·
well crap jerry i wish i had saw this before i left for advanced auto , ill list what i bought and maybe you can tell if i got ripped off or not lol
i went in and said i need plugs wires a distributor cap and rotor button for a 98 wrangler with the 4.0 6 cyl and this is what i ended up with BWD z-series cap and rotor button, Xact brand plug wires, and champion copper plus rc12lyc plugs.... all are supposed to be oem according to the parts store add a can of carb cleaner and a can of fluel system cleaner and my total comes 70.60 before tax
 
#7 · (Edited)
Earlier 4.0L engines like yours aren't especially fussy about their spark plugs so long as they are the right heat range. Those RC12LYC plugs will work fine, they just won't last as long. The fuel system cleaner wasn't needed because our fuel systems are kept very clean by today's gasolines that have more than enough fuel injector cleaning additives. That didn't used to be the case but it is now.

I'm no fan of Xact ignition wiring, I don't believe its quality is worth installing. I've also read enough reports that it pulls apart too easily for future spark plug changes too.
 
#8 ·
Hey TJ,
I am the technical manager at Autolite. We sell a wire set called pro series. It is sold at advance auto parts. It is an exact fit duplicate of the OE wires, the boots come pre-greased with the correct silicone grease. I recommend changing the air filter and fuel filters, new Autolite XP985 plugs and pro series wires. PM me with your address and i will send you a set of plugs. I happen to have a extra set of XP 985s laying around. These are fine wire iridium plugs, the best technology. Sorry guys, only have one set to send! Want to learn more? go to autolitechallenge.com/pro and watch the videos there. Do it before august 31st and you can get a free carhart jacket!:wavey:
 
#11 ·
Only other piece to add would be to be very sure to check distributor to plug wiring for correct firing order. Hadn't had to touch a motor in twenty years and my first trip back under the hood was most embarrasing.:banghead::banghead:
 
#12 ·
While plug wires aren't bad if you do them one at a time, I do love the coil pack, couple bolts off it comes. So easy I showed my 9yo daughter how to change the plugs, now if I can just teach my wife basic maintenance.. But I think that would lead to an episode of Divorce Court ;)
 
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