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All around best spark plug for Inline 6?

Q

Quills

NAXJA Forum User
Location
Spokane
I was just curious as to what people think is the best spark plug for fuel economy, size of spark, quality and performance. I guess the same for the ignition coil too. Currently I am running Bosch Platinum plus 4's. I would consider running something else though.
 
If you had bothered searching for 30 seconds you would find out that the bosch crapnums are a gimmick and don't do jack for a 4.0. In fact I had some and had cold weather starting problems.

Stock Champion regular old plugs work the best. Some claim the dealership sells better quality plugs, but in my experience they sell whatever they have. last time I bought plugs at the dealership they gave me NGK which is also acceptable in the 4.0.



Oh and I bought into the hype "better spark=better mileage" at one time. It's pretty much bullcrap. My Jacobs ignition netted me squat.
 
Good ol' Champion Truck plugs work great and their gold and black.
 
I am running the autolite platinums, can't really tell a difference. But I do work at an auto parts store and can tell you that most things don't run worth a damn with the bosch plugs. I usually will recomend the autolites or the NGKs... just my two cents.. Got a friend with a 4.7L stroker in his and he runs the champion truck plugs and swears by the things...
 
Our 4.0's require a resistor type spark plug.
From Champion...
It is strongly recommended resistor spark plugs be used in any motor that has on-board computer systems to monitor or control engine performance. Use of a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion. Resistor plugs are also recommended on any vehicle that has other on-board electronic systems such as, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer.

If you have an outboard marine CDI (capacitive discharge ignition), (such as Johnson and Evinrude), make sure to use a plug with an inductive type resistor (such as a Champion Q-type or NGK Z-type). Use of non-inductive resistor type plugs on these motors can create an open circuit within the spark plug (it will become a dead plug).

Mallory, MSD, Crane and Accel also produce a high output ignition CDI system, however, these should not be confused with a marine style CDI as mentioned above. For an automotive high output CDI system it is imperative you consult that manufacturer for plug specifications for their system. Some high out put systems specify the use of resistor plugs, while others will fry the internal plug resistor turning its 5k ohms into 60k ohms.

As a rule, performance is in no way impaired by resistor spark plugs. The only exception to this may be some models of high output CDI specify non-resistor plugs.


If you want good performance any of the following have worked well for my 96/97;

Champions: 412 (stock), 4412 (Truck Plugs), 2412 (Gold Paladium)
AutoLite: 985

Search here and Google as well, as there is a wealth of info out there.

HTH. -B
 
redneck said:
Good ol' Champion Truck plugs work great and their gold and black.
Click to expand...

I had a set of Champion 4412 truck plugs in my XJ for about a year and they flat-out sucked. Power was noticeably affected (felt sluggish), fuel economy dropped by about half a mile per gallon, and it only barely passed smog. I can't find anything in my notes regarding what I replaced them with (OEM NGKs, I think) but it's been running a lot better since the truck plugs were replaced.
 
I've been running Bosch single platinum AP3924 spark plugs on my 87 Renix, currently 249,000 miles, 24,000 miles on the Bosch single platinum AP3924 spark plugs so far and they still look like new, gap has not worn in 24,000 miles.

I am planning some plugs and gap experiments on mine soon to see how mileage is affected, but to my knowledge the plugs I am running work fine with the Renix engine and Renix stock set up. Most of my problems were bad wiring harness wiring, worn out sensors, and worn out parts, not the choice of spark plugs, but I have never tried the other plugs so I may not know what I am missing?
 
I never noticed any problems wth the single platinum plugs, only the +2 and +4 varieties. When I did my research on the cold start problem I came up with the result that the Jeep ignition doesn't like the fancy plugs. Swapped to a champion and got smoother idle, and no starting problems.
 
casm said:
fuel economy dropped by about half a mile per gallon
Click to expand...

You noticed a drop of .5 MPG?

My mileage would vary more than that depending on how hot/cold it was or if it decided to rain that day, or if I decided to pass someone on the highway instead of cruise normally... :confused:

I run the Champion Truck Plugs, does fine, passed NJ emissions @ 175k miles w/perfect scores.
 
The only way I could keep my Jeep from throwing P030x codes was by using the Bosch Plat +4.

(MY2001, DIS)
 
This won't be the first or last time I have discussed spark plugs...the best are NGK....the next choice would be AutoLites....with the Champions being third.

We run standard NGK plugs in two dragbikes with 15/1 compression that turn in excess of 11k with heavy nitrous loads. Nuff said...

Just stay away from wierd off brand multi electrode junk...they are garbage. If required we can have a discussion about spark shrouding.
 
vetteboy said:
You noticed a drop of .5 MPG?

My mileage would vary more than that depending on how hot/cold it was or if it decided to rain that day, or if I decided to pass someone on the highway instead of cruise normally... :confused:
Click to expand...

Thank you. Glad somebody said that.
 
Root Moose said:
The only way I could keep my Jeep from throwing P030x codes was by using the Bosch Plat +4.

(MY2001, DIS)
Click to expand...

I wonder if that is not a difference in the ignition systems and computers between 1987 (renix), 1991 (Chr OBD-I), 1996 (OBD-II)..... and 2001 (distributorless, coil on plug??)???

Goodburbon,

Thanks for the clarification as to 1 electrode, +2 and +4 platinum plugs on the older jeeps!

Quills,

What year is your ignition system, is everything stock on it?
 
Hahah :looney: 4412 truck plugs here no probs. Plenty of power for what I'm doin with it.
 
you mean the annoying skip ive lived with for 2 months that caused me to replace a cam and crank and TPS sensor that didnt change a thing is because i put bosch platnium 2's in my jeep if so i'm changing them tomorrow!
 
So what's the recomened plug for 2000,01 models coil on plug.Been using the autolites with out any problems.
I would agree that the NGK are the best. I boost my Saab above 20psi and the NGK's never burned out. I cant say the same for some special ZEX forced induction plugs that I literally melted,and the piston.:doh:
 
theoriginalscion said:
So what's the recomened plug for 2000,01 models coil on plug.Been using the autolites with out any problems.
I would agree that the NGK are the best. I boost my Saab above 20psi and the NGK's never burned out. I cant say the same for some special ZEX forced induction plugs that I literally melted,and the piston.:doh:
Click to expand...


use whats been working, why change from the autolites that you have in there.
 
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