What is the best brand of plugs for the 4.0L Jeep Cherokee engine? I have Bosch Plat + 2 in mine and have not had any issues.

I'm using the same type (Bosch) with no problems. I read in a previous post that Champion is supposed to be good also.

I'm using the "Truck" series plugs. Champion makes them. Have read some complaints about running rough at idle. After installing mine it did seem to have a little bit of a rough idle. They come with gap preset. Well I took mine out, checked the gap. About half were right, half gapped too wide.

Made them all the 0.035 gap, no more problems.

Jim

I replaced my autolite, god knows how long they were in there with Champion ( plain ones) Had one fouled out afetr 2-3k miles, replaced with Autolites have not had a problem

I use bosch platnium tipped for my '88 I-6 and no problems at all. These are in my opinion the best.

Original equipment fresh from the factory is Champion RC12ECC. I relace with everything original. Over 69,000 miles on it since I bought it new and it runs better than new. I use Mopar replacement oil filters and batteries, ect. But for some reason they did not put Mopar plugs in it at the factory. My older Cherokee had Champions in it too. I don't like the "split-fire" or the BOSCH platnums. I truely beleive they are a waste of money and in some cases cause problems. But that's just my opinion
tb

I just installed the Champion "truck plugs" and seem to have a bit of a rough idle when the Jeep is cold. Smooths out after warming up usually. Previously, I ran just plain old Champion plugs, and it seemed to do better with those.

Mine did that too until I double checked the gap. Had some that were too wide.

Jim

I run the Bosch platinum's in mine. 170,XXX miles on my third set (after the originals) and it still runs like new. I always change the cap, rotor and wires at the same time. If you look at the maintenance schedule I believe this is what the manufacture recommends. I think any plug will work fine as long as they are replaced on schedule and the rest of the motor is in good shape.

Bosh it good as well as Champion. if you get the 8mm plug wires, you will get better preformance and better gas mi.

Irridium Plugs ARE the best choice by far.
They outperform Platnum hands down but cost 3 times as much.
Brand wise...NGK is the best plug on the market
Nippon Denso is a close 2nd
I have researched this extensively

Irridium Plugs ARE the best choice by far.
They outperform Platnum hands down but cost 3 times as much.
Brand wise...NGK is the best plug on the market
Nippon Denso is a close 2nd
I have researched this extensively

Is Irridium a type of plating on the electrode ? Are all NGKs Irridium, or do you have to specify ?

Is Irridium a type of plating on the electrode ? Are all NGKs Irridium, or do you have to specify ?

Irridium is what the electrode is made from. NKG make 3 types of plugs.
1. regular
2. NGK-R Higher Performance/Racing
3. Irridium
You must specify you want the irridium plug. They usually cost about 12.00 each but for a 4 or 6 cylinder the performance increase is worth it.

Almost EVERY new car comes factory with Irridium plugs now.

I haven't noticed a difference between the bosch plats, spitfire or champions running in my 1990 Cherokee Ltd. I would recommend the cheaper Champions.