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Posted

I'm sure I'll get 10 different answers from 10 different people, but here goes. I think I need to throw in some new plugs. What's generally considered to be a good replacement?('89 4.0)

I'm very careful about this since I've had other jeep motors throw fits if I ran anything other than the OEM recommended plug. I've also seen definite improvements(like switching to Splitfires in my Harley. WOW!).

 

Watcha runnin'?

Posted

I was going to try the champion truck plugs. But instead bought the OEM ones. One more job to do this week. Its great to have a project to do on your jeep.

Posted

Champion is the recommended plug from OEM.

 

Bosch is the chosen performance upgrade from OEM.

 

NGK is an acceptable upgrade that will work fine and was actually OE in some later model 4.0L engines.

 

Most others will cause you problems ;) . :cheers:

Posted
ngk iridium IX plugs are the best.
I have had several people talk about them, but have no experience with them yet. Everybody says that they are good.
Posted
Most others will cause you problems ;) . :cheers:

Especially platinum plugs.

 

Stay with standard plugs. NGKs are best, Champion truck plugs are a distant second, all else is tied for fourth.

Posted
i used iridium plugs in my honda, they were fine, but never in a 4.0

 

I used them in my 92 xj laredo 4.0HO when i had it and absolutely loved them. they were very expensive but lasted the rest of the cars life.

Posted
Most others will cause you problems ;) . :cheers:

Especially platinum plugs.

Bosch Platinums are what you get from Chrysler if you order Mopar Performance spark plugs though. I have them in my '95 YJ and the same plugs have been there for over 5 years now. They are the Platinum +4's though, not the regular platinums if that makes a difference.
Posted
I ran Autolite Platinums in both my 4.0 XJs and never had a problem with them.
You are fortunate. Autolites do not typically work in a Jeep, Chysler, AMC etc, etc... of any type.
Posted
NGK.

 

The standard ones, NOT platinum.

 

Have you seen this little chart for NGKs?

 

http://www.spark-plugs.co.uk/pages/tech ... l_code.htm

No.

 

It's not an application listing, it's a chart that you use after you see what plugs fit your application, to see what type of plug the part number represents. I never had a need for that. I get them at Advanced Auto (same company as Shucks and Checker in other parts of the country) and just ask for the standard plug for a 4.0L Jeep.

Posted

I was leaning toward a set of Bosch Platinums, but you are saying to stay AWAY from platinums, or is it only the NGK platinums?

 

 

Also, I don't have a manual. Don't know the proper plug gap. Anyone know off the top of your head?

Posted
I was leaning toward a set of Bosch Platinums, but you are saying to stay AWAY from platinums, or is it only the NGK platinums?

All platinums.

Posted

Hey Eagle...not trying to be argumentative, but I am curious as to why you say stay away from Platinums? I have run Bosch Platinums in all of my Jeep and Ram Truck engines for many years now with no ill effects. I know many others that have done the same on my recommendation and they are very happy with the results too.

 

So...as I said...just want to know why you have such a drastically different opinion that what I have found from most other Jeep sites/forums ;) :cheers:

Posted
I'd have to say its the price difference,, 2 bucks a plugs vrs 6..
Yea...some people go by that, but I am a firm believer that you get what you pay for so I virtually never buy something based on a low price :D .
Posted
I'd have to say its the price difference,, 2 bucks a plugs vrs 6..

Nope. It's because I've heard too many stories of the platinum electrode tip breaking off and taking out the piston. The stock plugs with the Jeep high energy ignition easily last 50,000 miles or better, so why mess around with a hand grenade in your engine?

 

I also tried a set of SplitFires in the XJ once. Didn't run any better than standard NGKs, and gas mileage was worse. Sometimes, newer and more expensive doesn't mean "better," it just means newer and more expensive.

Posted
Sometimes, newer and more expensive doesn't mean "better," it just means newer and more expensive.
I won't argue with that :D . I have spent more money on things and been disappointed too.

 

Thanks for the info. I always like to hear all sides of the story :cheers: .

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