# CRAZY CARBON



## redneck truck (Oct 4, 2004)

since i bought this truck (93 pickup, ka24e), i have replaced the spark plugs twice (at $5/set its not that big an expense), and within a few thousand miles they become caked with carbon. also, the tip of the plug (or whatever you call the part you bend when you "gap" it) is a light tan color, in contrast to the black of the rest of the plug. 

it is safe to say that the rest of the inside of the cylinder is likely in similar condition, but i was wondering why. on a properly-running engine with good compression, and that passes emissions, what causes carbon buildup and how can it be prevented?

on another note, i picked up a quart of "fuel power" (fuel additive sold on www.bobistheoilguy.com) and ran it through with a few tanks. under similar conditions on my friend's LT1 trans am, he pulled out a spark plug before he ran a couple tanks and after, and before, the plug was caked like mine, and after, it looked almost new. needless to say, i was disappointed that my use of it did not yield the same results. so, what would you say the problem is?

a little more background: compression is 160-165psi on all cylinders, and when i pour a capful of oil into each cylinder before testing, i get another 5psi out of it. base ignition timing is set at 10-12°BTDC. let me know what you think. thanks!

- Bryan


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## lshadoff (Nov 26, 2002)

Check out the photos of spark plugs. Do yours look like any of these?

Lew


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## redneck truck (Oct 4, 2004)

Actually, they are about halfway between "ideal" and "dry: black soot buildup". so maybe i am running slightly rich, or my ignition system is slightly failing ..lol.. well the slightly rich is unlikely, just because of the extremely low hydrocarbon and carbon monoxide numbers i am getting, coupled with my excellent gas mileage. also, when i run computer self-test number 2 (air fuel mixture control), the flashing lights indicate an ideal condition, and the o2 sensor is new and functioning. that said, i think it is safe to say the problem is ignition. so how would i go about testing for a failing ignition component? i assume the only thing that can fail in the ignition system is the coil, and, i remember from when i had the timing light on the coil wire, it would occasionally very briefly not light up. is that a problem with the coil, or the ecu? or is there another link in there that could be failing? let me know...

- Bryan


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## lshadoff (Nov 26, 2002)

The things to check are the spark plug wires, distributor cap, and coil. The first two are the most common problems.

Lew


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## redneck truck (Oct 4, 2004)

wires, cap, and rotor are all brand new and in excellent condition, so i guess it falls on the coil. how do i go about checking that? id hate to spend $43 for a new one only to find out that it wasn't the problem at all. let me know, thanks

- Bryan


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## lshadoff (Nov 26, 2002)

You can measure the resistance of the primary and secondary coils. It should be about 1 ohm for the primary and 10k ohms for the secondary.

I'm not familiar with your ignition system, but there may be a power transistor and a resistor in the circuit, but usually there is no spark if they are bad.

Lew


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## redneck truck (Oct 4, 2004)

cool thanks for the info ...as soon as i get my hands on a multimeter i will test it. i also tried some sort of spark plug tester they sell at autozone - spark plug wire plugs into it, and it clamps onto the frame, and the circuit has an adjustable gap ..kind of like testing via your spark plugs, but less dangerous. We tested my friend's LT1 and the spark jumped upwards of an inch (at the 30kv mark) and was a bright bluish white like lightning. we tested mine and it worked intermittently up to 40kv, and consistently just above 30, but the spark was more orange. is this an indication of a problem? i remember hearing mention of spark color, but wasn't sure if it was pertinent. let me know, thanks

- Bryan


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