So I replaced my spark plugs about 6 months ago. I really only started driving it about a month ago. I put in Champion Platinum RC12PEC5. My dad says they are getting hot. Whatever that means. I do notice the electrode stick thingy is not burning straight. It goes off to the side a little. Do I have the wrong plugs? My dad things these plugs are to long

 

4.0's like champion coppers

 

Not sure what year your XJ is but I see that it's a newer model by your avatar.
Years 99-01 like NGK coppers
Anything earlier like Champion coppers

Switch out those plugs and see what happens

 

I've had multiple problems with Champions over the years. Different cars.

I wouldn't put Champions in a lawn mower now.

I use NGK Platinum now in almost everything. Excellent results.

 

Thanks guys. We put NGK plugs in our boat that has twin 454's and we saw an increase in power. I'll look into new plugs. I've had a small amount of a rough idle and I wonder if the plugs have anything to do with it. And yes I checked the IAC so I know it's not that

 

As others have said. Your 2001 should have NGK copper plugs in it.

Skip the platinum, 3 prong, 4 prong, unobtanium fancy ***** plugs and give the engine what it's designed to use.

This is one of those situations where cheaper is actually better.

 

The OE spec is RC12ECC, says it right uder the hood. They've been superceded by NGK ZFR5N though, which conveniently are cheaper. Guaranteed performance in a 4.0 with guaranteed compatibility. Most 4.0s don't do well with Platinum.

 

I've got close to 30,000 on my Bosch Platinum 4's. Still getting the same mpg increase I got by choosing them. 16 and 21. Not saying any other plug wouldn't do the same but I can't see how they would do better. Been meaning to pull one to take a look. Probably will when I replace the leaking valve cover.

 

Hey guys. I have a few more questions. How are the autolite plugs? Should I just stick with NGK for right now? And is this plug in the picture a copper plug? I can't fine anywhere where it says copper. Thanks guys

 

Yeah ZFR5Ns are the copper V-Power ones

 

Got ya. Alright thank you. I'll go get these plugs today when I get done working. Would having the wrong plug cause the engine to run a little rough and to have problems starting?

 

Absolutely

 

Yeah. Don't forget to set the gap properly

 

Yea I will .035

 

Platinum gap is factory set. Don't alter them.

You will probably damage the plug if you try.