I think the parts place I ordered from gave me the wrong plugs. I've done research in this forum and others and everyone seems to have their own opinion on what's the best plug but I just want to use the oem copper Champion plugs that are the direct factory replacements. I saw RC12LYC and also RC12YC mentioned. Well the ones I was given were the RC12YC not the "L" ones. Well I just pulled my old plugs and they are marked RC12ECC and they are noticably longer than the new RC12YC I was sold. I put in the new ones and it started up but seems to be idling rougher than before like a little "wobble" in the idle. Is the L version of the YC plug the proper ones? It ran good on the ECC but since they werent changed in awhile I wanted to put in all new ones.

 

Just buy ngk ZF5YN and you're golden. Remind my drinking brain, 99s have wires and distributor too or no.

 

Haha Yea plug wires and distributor. I'd rather use NGK bc I've always used them in the past but people kept telling me just use the oem champion cooper in this.

 

See I'm hoping someone like salad or cruiser pops in cause I'm trying to remember the reason they changed spec. It's the same 4.0 engine so no reason ngk shouldn't work for ALl years. I just did my plugs on my 01 and again I used ZF5YN and jeep runs happy and smooth. Also make sure you put the wires back on properly and everything was clean going back in

 

Yea I do 1 plug at a time so I don't mix up the wires. These RC12YC are definitely shorter than the ECC Champions that were in it, Im pretty sure they're the wrong ones. I think I needed the L version for the Champion plugs. I'd prefer NGK if they do work well on the 99s though.

 

There is nothing wrong with the NGK plugs. They end up lasting a little longer than the champions...that's about the only difference. In any case whatever plugs you use just make sure to check and have proper gap clearance in the plug. Engineers dot just do the "best when designing anything...they look at a lot of different variables..cost, dependability, function, ect... maybe they knew the champion plugs where somewhat inferior..but cost less..or they used them so they could get more factory service tune ups...

 

So nothing good to add to a thread but post your opinion around. No one here was acting as an engineer and you speak very greatly out your own *** not even know what engineers look for. You just trust them. I bet doctors just love using sugar pulls with you instead of medicine cause you just trust them above others. **** off

 

Nice! Get 'em tiger, LOL

 

Awesome that's what I needed, I was sure these RC12YC were the wrong ones, needed the LYC ones, thanks!

 

I'm always amused when self-professed high horsers think that the engineers who designed it at the the time know everything. Recalls? Yep. New technology comes out? Yep. Aftermarket parts that make more power over stock parts? Yep. Aftermarket parts that last longer than stock parts? Yep

 

Those plugs will do fine...just make sure the gap is correct (.035 iirc)

 

LOL

 

Ha

 

I was gonna explain the function of complex analysis in engineering but what do I know....I'll just leave this here.

http://en.m.wikipedia.org/wiki/Complex_analysis

Maybe this will help him understand why engineers dont always get it right...but do at the same time.

 

Credit goes to cruiser, LOL