best oem plugs/wires for 99XJ
 

Recommendations for replacement plugs and wires?

Are there any specific OEM spec plugs that work best? what about split-fire (yes, no, hell yes, or hell no)?
And wires? just standard OEM mopar? or?

I have a new set I was going to put in my Tacoma before I ended up selling it a while back. They are NGK split fire I believe? That was recommend for replacement in that motor, but don't know if they would be good for the XJ or not. She jacks up on me on her own, don't want to help it along by doing something stupid. :)

knowledge of OEM spec parts or good/bad personal experiences welcome :)

i use ngk zfr5n...? i think plugs and whatever cheap wire set i can find. i always do plugs and wires at the same time, somewhere in the 40-50k mile range. i found that the champion copper plugs are junk and within 18k i had to replace them. i use ngk plugs in every internal combustion engine i own.

I used the plain NGK plugs and NAPA blue wires. I think most will recommend the cheap NGK or Champion plugs. It seems the XJ doesn't really care for fancy plugs.

Absolutely^^^^.

Plugs, wires, cap aND ROTOR EVERY 30,000 MILES.

Champion plugs gapped to .035 for your 99. NGK are fine too.

Do NOT install the Splitfire plugs; many (not all) have had issues with them in the 4.0 engine.

Quality plug wires, brands can vary...just buy good ones. Same to be said with the distributor cap and rotor. Buy the premium stuff.

Good to know... it's kind of the blue collar working class vehicle that it is. :)
All three every 30k? .... I thought those had a longer lifespan than that. Or is this something specific to Jeeps? and/or our 4.0s? I can honestly say that with mine having 99k on it and where it came from, I really don't know if the PO ever did those. So it's somewhere to start I guess. lol.
Thanks for the tip on those. If that's what I have left over, I'll just get a different set, they're not super expensive, so won't take the risk.

Any particular brand of wires and rotor that ya'll have had good luck with now or previously?

Now below is what I'm experiencing... and not having any service history about my XJ from the PO... (which I think is a complete idiot when it comes to vehicles)... I'm starting by replacing the obvious things that should always be replaced first since I'm fairly certain they probably haven't been done for a good while. Mainly because the root issue could be merely magnified because these parts are also worn. I'm trying to get her to that middle plateau of reliability.
below:
What is the most common stalling issue (doesn't actually shut off).. but after warmed up to op. temp, a few miles down the road, will just lose power for several seconds. Just enough to have to pull over let it idle for several seconds, then she seems fine to go again. Has happened twice so far.
99, 4.0, auto,
Starts and idles just fine this is only after I've been driving down the road for several minutes first. Any ideas?
I will be starting with testing the fuel pressure, but don't know if that's really the culprit... since she fires right up, idles fine, then doesn't cause an issue until after driving for a few miles. Doesn't seem to matter what speed... had it happen in-town and at highway speed too.

Do the 99's have an in-line fuel filter like say on the 97's?
Thanks for the help... I've got probably more into my XJ then I would like to.. but drive-train is solid, low miles, damn near completely rust free. And replacing her with something else, well it would cost way more then what I have into it in order to do that. So a few more bucks into it is worth it I think.

Factory recommendation was plugs, cap and rotor every 30K. Wires at 60K.

Guess what happened between 30K and 60K?
The wires took a dump.....We went to all of it at 30K.

makes sense. I'll work on getting those replaced soon here.
do you honestly think that fuel pressure would be a very likely possibility with no issues until already on the road for a few minutes? I'll be testing it probably next weekend too. If memory serves, I should get 49psi at the schrader testing port on the fuel rail correct? (plus or minus a hair or two)

BTW... I just found out something about the '99 that makes me very sad....
They changed from having an in-line filter along the frame rail under the driver's side of the vehicle to it being right on top of the tank. What flippin' genius thought that redesign was a good idea? Should've been his/her last day with Chrysler that's for damn sure. I mean hell... if you're gonna have to drop the tank, might as well do a fuel pump while you're there....or maybe that was that little dirtbag's idea for it.
Kind of like every time I tore into my Tacoma's 3.4 V6 to do a timing belt.. might as well do the water pump at the same time as they tend to fail very close together each time and it always took me a few hours to get that deep into it.

I got the Mopar cap/rotor/wireset from Amazon for about $50 - so about what I'd have paid for a decent set of aftermarket parts. Jeep runs nice with that and the champion plugs.

Thanks Pat.... I might just hit up Amazon for that set soon. That's not a bad price for it.
On the XJ and from other input... I think I'm safer going OEM Mopar for these replacement parts. Sometimes aftermarket is good quality too...but in trying to resolve my current issue(s), I'm just not going to roll the dice. That's not what I do anyways on a DD. lol... because I've found that Murphy really likes to follow my butt around most times.

Anytime brother. I felt the same way on the price and figured that you can't go wrong with Mopar. Make sure to get a good amount of di-electric grease though, I went through most of my little tube of it.
Murphy is a real jerk, but not unexpected when dealing with a 20+ year old vehicle. Good luck to you that he finds someone else to mess with!

he's got my private number some how Pat.. he's such a dirtbag.

I'll just pick up a tube of it when I get the parts ordered.