plug for 01 Ckerokee 4.0 w/waste spark

[Donald]

So I have read on this forum not to use a plain platinum on this engine because its a waste spark system. I understand the reason. But would not the same hold true for a plain copper plug? What about an IR plug. Rockauto lists several plain platinum plugs & some copper & some double platinum & two IR plugs.

 

[01rangerxl]

My 2001 Ranger used a waste spark system, but it had two spark plugs per cylinder. Four of the plugs were there solely to burn off anything left over after the combustion cycle.

I believe all of its plugs were platinum from the factory. I never had a problem with them.

 

[Donald]

Originally Posted By: 01rangerxl
My 2001 Ranger used a waste spark system, but it had two spark plugs per cylinder. Four of the plugs were there solely to burn off anything left over after the combustion cycle.

I believe all of its plugs were platinum from the factory. I never had a problem with them.


I thought a read somewhere that from the factory, companies used two different plugs, one for each end of the waste spark system. But not for replacement plugs.

 

[Bluestream]

Originally Posted By: Donald
So I have read on this forum not to use a plain platinum on this engine because its a waste spark system. I understand the reason. But would not the same hold true for a plain copper plug? What about an IR plug. Rockauto lists several plain platinum plugs & some copper & some double platinum & two IR plugs.


You want the double platinum or IR plugs

 

[rslifkin]

Honestly, it'll be fine with plain copper plugs. The 4.0, even the later ones with coil packs, don't need anything fancy as far as plugs. Some people say they run better with cheap plugs than fancy plugs, but I've never tried anything other than champion coppers in my mom's 99 GC 4.0 (has coil packs).

 

[Spazdog]

If you can still find Champion Truck plugs with the black insulator, get them.

They have a copper core in the center and side electrode.

Every Jeep 4.0 owner that I've ever talked to really liked them.

 

[Chris142]

The only plugs that the guys (and me)on the Jeep Forums recomend are standard Autolite 985 and Champion RC12ECC plugs, Champion stopped making the truck plug which was a #4412.

Autolite double Platinums work too. APP985.

I don't know if the IR plugs will work. The 4.0 w/o a distributer is very picky about what plugs are in it.

Any special plug, single platinum, multiple electrode etc will cause missfires, CEL light etc.

 

[440Magnum]

Originally Posted By: Donald
So I have read on this forum not to use a plain platinum on this engine because its a waste spark system. I understand the reason. But would not the same hold true for a plain copper plug? What about an IR plug. Rockauto lists several plain platinum plugs & some copper & some double platinum & two IR plugs.



Double platinum should work fine. The problem with using a single-platinum plug is that 3 of the plugs will erode their copper electrodes much faster than the other 3. Double platinum or double copper either one will work fine and wear uniformly.

Fortunately changing plugs in the 4.0, even the 2000 and later ones with the "coil rail" waste spark system, is an easy job. A little experimenting with plugs isn't going to be a huge chore like it is in, say, a v6 minivan where you practically have to pull the engine to get to the back 3 plugs.

Its also pretty easy on plugs, really, and I tend to just use plain copper Champions in mine. The single most critical plug feature for a 4.0 is for the replacement plugs to have the same extra-long extended tip and side electrode as the originals. There are non-extended tip plugs that will screw in and sorta work but will immediately cause misfires and CELs.

 

[mechtech2]

Where do you think the copper is, on the tip?
NO!
Use double platinum plugs in the car in all the holes.
[The factory may have used single plats with alternating +to- and -to +.]
Use copper platinums if you like. I could care less if there is copper in there or not. A total non issue.

 

[Donald]

OK, so what is special about an IR plug? Aside from the tip being made of iridium? Is it a single or double? Won't the same be true of a single IR as would be for a single platinum. I don't think I have ever looked at an IR plug.

 

[mechtech2]

IR = iridium?
It is a precious metal like platinum that is on the tip of the firing ends of the spark plug. Aftermarket plugs are almost always double plat or iridiums. Single is for factory cost savings.

Plain steel wears rather quickly. Platinum or iridium wears very well. That is why 50-100k is possible out of them.
Platinum has slightly more resistance than iridium, and iridium is a better choice if costs are not a concern.

 

[Donald]

Originally Posted By: mechtech2
IR = iridium?
It is a precious metal like platinum that is on the tip of the firing ends of the spark plug. Aftermarket plugs are almost always double plat or iridiums. Single is for factory cost savings.

Plain steel wears rather quickly. Platinum or iridium wears very well. That is why 50-100k is possible out of them.
Platinum has slightly more resistance than iridium, and iridium is a better choice if costs are not a concern.


Are the aftermarket IR plugs double or plain IRs? If they are single then why don't they have problems in a waste spark system?

 

[Eddie]

My 95 4.0L with a distributor and hall effect system was NOT a waste spark system. The engine came with Copper Champions (not my favorite company) but, they worked beautiful in my engine. I would stick with what ever OEM plug came from the factory with. Ed

 

[Donald]

Originally Posted By: Eddie
My 95 4.0L with a distributor and hall effect system was NOT a waste spark system. The engine came with Copper Champions (not my favorite company) but, they worked beautiful in my engine. I would stick with what ever OEM plug came from the factory with. Ed


Ed - good idea unless the car came with 3 plugs of one type and 3 of the other for each end of the waste spark system. I am told you cannot buy them as the vehicle manufacturer was worried people would screw things up, and they probably would.

 

[440Magnum]

Originally Posted By: Donald
Originally Posted By: Eddie
My 95 4.0L with a distributor and hall effect system was NOT a waste spark system. The engine came with Copper Champions (not my favorite company) but, they worked beautiful in my engine. I would stick with what ever OEM plug came from the factory with. Ed


Ed - good idea unless the car came with 3 plugs of one type and 3 of the other for each end of the waste spark system. I am told you cannot buy them as the vehicle manufacturer was worried people would screw things up, and they probably would.


I can't believe that such things even exist or are used. Sure, they might save a few cents per plug, but the logistics tail of keeping different parts bins on the assembly line and then insuring that the right ones go in the right holes would quickly eliminate any savings on the individual parts.

 

[440Magnum]

Originally Posted By: mechtech2
Where do you think the copper is, on the tip?
NO!
Use double platinum plugs in the car in all the holes.
[The factory may have used single plats with alternating +to- and -to +.]
Use copper platinums if you like. I could care less if there is copper in there or not. A total non issue.


No, its actually important. Copper is by far the best heat conductor (and electrical too, but that's a non-issue with 30,000 volts and microamps of current) of all the metals being discussed. Platinum and iridium are rather poor heat conductors by comparison, steel is in the middle. The high thermal conductivity keeps the plug's tip from overheating during high-load conditions, without making it load up during light load/idle conditions. Its there for THERMAL reasons, not electrical.

 

[SEMI_287]

Like the Jeep forums say just use the factory Champions. Its what its designed for and work the best.

 

[TheTanSedan]

Use NGK ZF5RN over the Champion R12ECC (ck #'s) on '00 and '01 XJ's as it is now the OEM part number and it tends to handle or prevent minor misfire problems better than the Champs. As always, check and correct gap to .35

The change is noticeable.

 

[Challenger71]

I use Bosch Platinum IR Fusion in my 01' XJ. Smooth throttle response and idle. I recommend them to you.

 

[mechtech2]

Originally Posted By: Donald
So I have read on this forum not to use a plain platinum on this engine because its a waste spark system. I understand the reason. But would not the same hold true for a plain copper plug? What about an IR plug. Rockauto lists several plain platinum plugs & some copper & some double platinum & two IR plugs.


That is bad information.
Platinum plugs are perfect for waste spark ignitions.
But I do not know what you mean by 'plain' .
And you can have copper platinum plugs.
Copper is in the core - it has nothing to do with the tip type.
Get double plats.