Thank you good to know.

 

Can you post a link to the ngk coppers all I can find are v power and platinum

 

NGK ZFR5N

 

I have at least twice that on them, haven't noticed any problems. I pulled them last fall and they still looked good, back in they went.

 

With Uber Sparkle, urine the winner's circle?

 

Ok so its the v power plugs

 

No. The factory recommended interval for spark plug changes is 30K. At the dealership we also did cap, rotor and wires even though wires weren't recommended until 60K. Reason being is the wires would fail before 60K.

Champions are purported to be made in china now by Wunhung Lo and his relatives. NGKs are made in Japan and are a very high quality spark plug.

 

I emailed NGK Tech and asked what the difference is between the NGK FR5-1 plug and the ZFR5N plug for the '98 4.0 vs. the '99 4.0.

My email:

Subject: NGK Form Mail

**** Contact Form & Tech Info Feedback ****

VehicleType: Truck
Make: Jeep
Model: Cherokee Sport
Year: 1999
Engine Type: 4.0 liter 6 cyl.
Comments: What is the difference between the FR5-1 spark plug ('98 Jeep Cherokee 4.0) and the ZFR5N spark plug ('99 Jeep Cherokee 4.0)?

Both engines have the same ignition system so why is there two different plugs recommended?
When: 4/16/2013 8:35:20 AM

Their reply:

Hello,

The difference in the 2 plugs is that they are different extended metal shell reaches. Chrysler is one of the only companies that does this. A normal plug would thread into the cylinder head and stop when entering the combustion chamber. The extended metal shell reach refers to a plug that the shell goes past the cylinder head. Also the amount of the projection that the center electrode protrudes into the cylinder is different, I believe that there was a slight tweak to the cylinder heads in this time frame.

FR5-1 - 3.0mm extended shell reach
ZFR5N - 2.5mm extended shell reach

Firing position

FR5-1 8.5mm
ZFR5N - 9.0mm


Best Regards,

Jason Norwood
NGK Spark Plugs ( USA) Inc.
Technical Services Administrator - Aftermarket Division
46929 Magellan Drive
Wixom, MI 48393
Office: (248)-926-7107
Fax: (248)-926-6938
Email: jnorwood@ngksparkplugs.com
ASE Certified
Ngksparkplugs.com

I think where he mentions "I believe that there was a slight tweak to the cylinder heads in this time frame." I believe he is talking about the 0331 head vs. the 0630 head. Maybe they are confused about the ‘99 GC with the 0331 head and the ’99 XJ with the 0630 head (?).
Here’s some reading about tip protrusion. Perhaps the FR5-1 8.5 MM protrusion in the 0630 head would be more beneficial than the ZFR5N 9.0 MM protrusion? Both of these plugs are "V-Power".


From WikipediA:

Tip protrusion

Different spark plug sizes. The left and right plugs are identical in threading, electrodes, tip protrusion, and heat range. The centre plug is a compact variant, with smaller hex and porcelain portions outside the head, to be used where space is limited.

The length of the threaded portion of the plug should be closely matched to the thickness of the head. If a plug extends too far into the combustion chamber, it may be struck by the piston, damaging the engine internally. Less dramatically, if the threads of the plug extend into the combustion chamber, the sharp edges of the threads act as point sources of heat which may cause preignition; in addition, deposits which form between the exposed threads may make it difficult to remove the plugs, even damaging the threads on aluminum heads in the process of removal. The protrusion of the tip into the chamber also affects plug performance, however; the more centrally located the spark gap is, generally the better the ignition of the air-fuel mixture will be, although experts believe the process is more complex and dependent on combustion chamber shape. On the other hand, if an engine is "burning oil", the excess oil leaking into the combustion chamber tends to foul the plug tip and inhibit the spark; in such cases, a plug with less protrusion than the engine would normally call for often collects less fouling and performs better, for a longer period. In fact, special "antifouling" adapters are sold which fit between the plug and the head to reduce the protrusion of the plug for just this reason, on older engines with severe oil burning problems; this will cause the ignition of the fuel-air mixture to be less effective, but in such cases, this is of lesser significance.

 

Fascinating read, Ken! Nice work. Next tune-up I might try the FR5-1 and see if there's any difference. Though I think most of us are already running the longer ones anyway

 

Some Seafoam couldn't hurt.

 

Ya probably need to run some thru it

 

Good to know,thank you

 

The best advice I can offer, and this applies to ALL automotive engines... unless the engine is "heavily modified" from stock, ALWAYS utilize the factory recommended replacement parts. The reasoning is simple, literally millions of man hours went into the research and development of every aspect of that engine to achieve a balance of power,economy, emissions, longevity and cost. I don't fall for any advertising gimick when they say "increases power and milage", especially when they have absolutely no idea of vehicle condition, maintenance history, operating conditions, etc... To put it simply, "stock" vehicles should use the OEM recommended stuff... When you start modifying engines with higher compressions, varying valve overlap, fuel and ignition curves, etc... Then you need to worry about heat range deviations, MSD boxes and such.

 

Just re-did all your tps tests with a good meter this time. Didnt realize my leads were toast on my last meeter so I borrowed a new one from my co-worker. All the testes turned out like they should. Would my O2 sensor play a role in the spark plug being black? Also what else would cause it to run rich? I have replaced the map sensor.

 

I bought a FR5-1 from O'reilly today to see what the difference was between it and the RC12ECC and the ZFR5N (see pic). Man, I'm not sure about that FR5-1, it looks spooky to me. The RC12ECC and the ZFR5N look identical but the unthreaded portion of the FR5-1 sticks out quite a lot and covers half of the ceramic. The threaded length is the same however, and the overall length from the flange to the top of the ground electrode look the same.

The FR5-1 cost $4.09 at O'reilly. Big bux.