salad

Words of wisdom here

The 4.0L is a very simple engine that, near the end of its life, was tuned very tightly to try to meet more stringent fuel economy and emissions targets. You should be checking the plugs more often than every 100k or whatever the supposed platinum plug lifetime is.

For any OBD2 XJ with a distributor I'd run (and this is what I have in my '99)
Champion RC12ECC or NGK ZFR5N
NGK RC-CRX026 (I like the blue, but the numbers are handy and they're excellent quality)
Champion/BWD C275 cap with brass contacts
Champion/BWD D228 rotor

pbudzy

Ok, so I will return the platinum plugs, I also agree that with the change interval it is probably useless to have a plug designed for 100k.
Also the Airtex cap and rotor where aluminum so they will be going back as well. I am going to try my luck with the ACDelco wires, because they are well built and I like the color, and in all my years as a service manager its the only plug wires I never had any problems with. Although I have not tried some of the ones suggested(so no one feel slighted)
I have had the Fram air filter in now for almost 2 weeks and definitely has a bit more pep and no noticeable change in MPG.

So, thanks all for your advice, next to start thinking about a 3" vs 4.5" lift....
opinions??? very mild off roader, basically only when I can find a dirt road or some mud to play in....not a regular weekend warrior at the moment.

Dief123

I would never buy Bosch plugs for any car I own even if my life depended on it, they are very cheaply made!

Pelican

^^Wow, I agree 100% that you should not buy Bosch plugs. Nor should anyone else who feels that they won't perform well in their Jeep. I didn't realize lives were at stake here.

My only point is that you who make the blanket statement that platinum plugs won't perform well in earlier model 4.0s are wrong. No one likes to be wrong so it obviously is important to all of you that you convince the XJ community that this guy can't possibly know what he is talking about.

I've continuously owned at least one XJ, and for a while two, since May 1985 and I love the things. I mention this just so you know I'm not some smartass who just wandered in off the street after picking up his first XJ with the short term intent of impressing all of you Cherokee Forum experts with my vast knowledge of Jeep lore.

I don't recall what plugs I used in my '85. I bought the '93 from a retired mechanic (not necessarily Jeep) who had bought it for his granddaughter some years prior. She didn't drive it much and he took it back to sell. He had the CPS replaced and bought various other maintenance parts to swap out, including six Bosch platinum plugs. I ended up buying the thing so quickly that he didn't have a chance to install any of the stuff. I did so as I had time, hence the original installation of the plugs.

It is obvious that it is important to many members of this Forum to make sure that everyone knows that platinum plugs won't work in the 4.0 and that Bosch plugs in particular are crap. I think someone even suggested something along the general line that those who use the Boschs are probably Krauts. I for one do have some "Kraut" blood in me along with some Scots, Irish and who knows what. Maybe some honorary Mexican since margaritas happen to be my all-time favorite beverage. I do not in any way, shape or form choose auto parts based on anything but performance.

So enough already! Lemmings to the cliff or whatever turns you on!

salad

I have no doubt that some engines run just fine on platinums, just as some AW4s will work on ATF+4 without issue. The point, at least the one I'm trying to make, is the OE spec is for guaranteed performance. As in, risk it if you want, but it's going to be a gamble.

cruiser54

Well stated.