What would be the proper spark plug to put in a 2002 Jeep Grand Cherokee Laredo 4.0 like to know what is used from the factory or what is suggested

 

I use NGK V-power ZFR5N in my 2k 4.0 for years now.

Chrysler recommends Champion plugs but the NGK's work better at least in my rig.
Check the owner's manual or the sticker in the engine bay for the Champion part number.

Whether you go with the NGKs or Champions, Chrysler recommends replacing them every 30,000 miles.

 

If I'm not mistaken, the coil rail motors came from the factory with NGK ZFR5N. That's what came out of mine the first time I swapped them. Champions were in the earlier motors that had distributor ignition. Apparently the NGKs work better with the waste spark ignition.

 

ZFR5N, make sure the gap is at .035 (check your firewall to make sure). Higher quality than Champions anyway

 

Here's a tech tip from Chrysler 'Star Parts' concerning spark plugs:



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I also hear that some people had NGKs from the factory in the later models.

But, the sticker in my 2000 engine bay firewall says Spark plug: RC12ECC which are Champions.
Champions were in my Jeep fresh from the factory back in 2000 the 1st time i changed plugs.

I also changed plugs recently in my '16 Patriot, got OEM $MOPAR$ replacements because i didn't want jeopardize the lifetime power train warranty....yep NGK's in the MOPAR box.
Yeah i know, could of saved a bunch buying them at AZ.

Champions used to be one of the goto plugs decades ago, not any more.
Same i'm hearing with MOOG suspension parts.

 

I still use moog in all my cars and trucks, hearing is one thing but knowing is another.....I have never had an issue.

 

I use that NGK plug in all 4.0s back to 1987. ZFR5N

 

I replaced my plugs in my 2000 with the NGK V-power ZFR5N about a year ago. I've since taken them out to inspect them a couple of times and they look great. They were pre-gapped to .035 and none of them out of the box were off .035.