pbudzy

Ok, so I have decided its time for a tune up...my 99 classic with a 4.0 has 160k on it and I don't know if it has ever been done. I have changed out all the fluids and found a valve cover leak so I have decided to do the valve cover, plugs wires cap and rotor.

I have bought the parts and saw many different opinions about the plugs to use...most say champion copper, however I like to use platinum...so I got the Champion 3034 part#RC12PEC5...opinions???

Second I got the wires...I liked the look of the red wires and the only red wires I could find at the parts stores where AcDelco 16-806g part#12487192 .....opinions???

Third I got the cap and rotor kit from Airtex.... don't know this brand but the parts look right and seem to be decently well built..prat#3D1158 ....opinions???

then I bought the permadry gasket from Napa, all my research points to this being the perfect gasket for the application, so no opinions needed on that.

Lastly I bought a Washable Fram air filter...... I have no experience with them, but they seem to let a bit more air flow and the fact it is washable is nice...I had just bought a new paper filter and keep that in the box for when I have to wash the other one and let it dry for 24 hours. that part#WA3901....opinions??

Thanks for reading and Happy Jeeping!

Dief123

i did a tune up on my 93' xj last year, i got msd wires, msd coil, and a red cap and rotor from a brand through summit racing and put in ngk plugs cause i really like them, i dont know if platinum plugs are worth it in a jeep 4.0 because of the old design of the engine but they will for sure last much longer. also look at changing your coil as i know the coils on 4.0s are known for leaving people stranded sometimes. i hope this helps you

scottmphoto

I don't think that you'll see much difference by using the platinum plugs. The 4.0 likes things simple and the Champion copper plugs work good. There's no reason to spend the extra money on the fancier plugs. Some have had problems running them though (I tried platinum in my last XJ and it ran better after I switched to Champion coppers). Make sure that your new dist. cap has the copper or brass terminals, not aluminum, it'll run better and last longer. Make sure that your air filter is good. I have never used the Fram air filter (I use the K&N OEM air filter as it is made well and is washable and more airflow) but make sure that you stay away from the Fram oil filters. They have low quality control and their anti-drainback valve doesn't work good in our 4.0's causing a bunch of dry starts. Use a Napa Gold, Wix or Mopar oil filter.

RTorrez1

The platinum plugs in the 4.0 are garbage. If you insist on using them expect them to foul pretty fast or you Jeep to run like crap. The 4.0 really does run better on the Champion or NGK copper plugs. I made the mistake of trying the platinum plugs once and I had them in for less then a week. It ran real bad and when I took them out they where all ready getting fouled.

EZEARL

Just replaced my Bosch Platinum 4's after roughly 30K miles of good service (16/21mpg). Gas mileage took a nose dive recently but performance was fine. Since I was expecting to get alot more than 30K out of the Bosch considering the cost I decided to go with Champion RC12LYC's. Gas mileage and performance are back to normal. We'll see for how long.

Pelican

The classic "to each his own" applies as always, but I have to disagree with the never ending flat statements that the 4.0 "doesn't like" platinum plugs.

I have run Bosch standard plats for 6 of the 8 years that I have had the '93 4.0 and have had zero problems. After hearing for years that Champion copper plugs were superior in every way, I tried them for two years -- fair test -- and couldn't find one particularly good thing that I could say about them except that they were worn out at that point.

The platinum plugs cost only a very few dollars more for a set but anyone who doesn't like them certainly shouldn't use them. Someone said recently that the 4.0's plugs were scheduled to be changed every so many miles (I forget -- 30k ?) and they didn't want a plug that lasted longer than that! HUH?

In truth I'm not sure why I respond to these plug threads...but I do know that there are others who use the platinum plugs and are happy with them.

Radi

The only problem I know of is with the later coil rail ignitions, waste spark systems don't play nice with single-platinum plugs. Half the plugs fire in reverse polarity. Double platinums are just fine.
I guess it's a cost/benefit thing. If you're going to change the plugs at 30K, there's no point in paying for a plug that lasts longer since you'll just be throwing it out.

cruiser54

NGKs or Champion Coppers, Belden wires from Napa, along with their premium cap and rotor which have brass, not aluminum contacts.

EZEARL

I am well satisfied with the service I got from the P4's. Maybe I was just asking too much to expect more than 30K out of them. IF I get 30K or more out of these Champions, fine. If I get substantially less then the P4's will have proved their worth. Time will tell. I do know I won't be replacing plugs based on how many miles they have on them but by changes in gas mileage and/or performance.

I'm running everything above except I've got Autolite Premium wires. They're doing GOOD so far.

cruiser54

Those Autolite wires may be just fine also.

belvedere

I agree 100%. However, the OP states he has read all the opinions about platinums in XJs, and bought them anyway, so I think he's just looking for validation.

cruiser54

Well, he's not getting it from me...........

You?

belvedere

LOL, no probably not. I learned my lesson many years ago. My parents had a Celebrity with the 2.8 V6, and those back three plugs were a b!tch. I was gonna "fix" that and use double platinums, so I didn't have to do it again for a long time. Upon start-up, it missed like crazy at idle. At higher RPMs, though, it was fine. I checked plug wires, etc, with no success. Finally swapped in a set of regular AC Delcos, like I'd used before, and all was well. Now, I only use platinums in vehicles that had them from the factory.

EZEARL

Only time will tell if he made the right choice or not. It seems experiences vary. As long as he has no actual failures and is satisfied with their performance he should be happy in his choice. I hope he's not concerned with the price difference. I mean we're not talking mega bucks of difference here.

belvedere

very true