Tuned cars with increased boost make more heat, and typically do better with one-step-colder plugs. But this may or may not be your problem.
In 2nd Gen cars, preignition and/or misfires are often a result of carbon buildup issues.
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BlimeyCabrio Oscar Goldman of MINIsLifetime Supporter
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Metalman Well-Known MemberLifetime Supporter
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Here is some great spark plug info posted by czar....
http://www.motoringalliance.com/forums/cooper-s-engine-drivetrain/3824-basic-guide-spark-plugs.html-
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ScottinBend Space CowboySupporting Member
^^^^^this
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There are still more black deposits around the edge of the piston so I purchased two more bottles of BG 44K Fuel System Cleaner, I will purchase and use a bottle for every gas tank until I'm satisfied there is no more (carbon) pre-ignition. Then I will use it once a month or every other gas up.
At first the layer of carbon on the pistons was soft and dry enough to scrape off using the tip (2mm tip) of a Steelman Bend A Light Pro through the spark plug hole. After using just one bottle the layer of carbon started clumping up together and then was completely gone after going through another tank of gas without BG 44K. Now I have a second bottle of BG 44K in there, we shall see what happens after three bottles of BG 44K.
Does anyone know of a service offered for this kind of problem that would yield better, faster and more thorough results from some kind of service shop? I don't trust my dealer because they told me that they added something special to the tank after the walnut blasting, I don't see any indication that they did any such thing.
I really appreciate the responses guys! -
Dave.0 Helix & RMW PoweredLifetime Supporter
A complete METH kit will cut down on that carbon but you may not want to spend that much money or mod your car that much.
I would only run 93 octane and keep cleaning when its needed. -
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Dave.0 Helix & RMW PoweredLifetime Supporter
Well that sucks you can not get 93. You could try adding a few bottles of good octane booster to your tank. Since they do very little a few bottles will not hurt.
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Metalman Well-Known MemberLifetime Supporter
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I'm not sure what the R5 means.
What's your question? -
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Dave.0 Helix & RMW PoweredLifetime Supporter
I do not know the exact difference between the plugs themselves but the S and the JCW are exactly the same besides the tune and JCW markup, stickers and badging.
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Ditto, just as a one step colder plug is recommended for a 15% or smaller pulley, possibly even 2 steps with a 19% depending on your outside influences, heat, octane & such.
My setup calls for 2 steps colder with the possibility of even 3 depending on how everything looks and reads on the bottle.
Here's some plug basics for anyone interested:
How to read Racing Spark Plugs
NGK Spark Plugs USA
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Metalman Well-Known MemberLifetime Supporter
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The S has a compression ratio of 10.5
The fJCW has a compression ration of 10.0
And if I remember correctly the boost level is different for the two engines but that would be dependent on the separate tunes... -
Dave.0 Helix & RMW PoweredLifetime Supporter