[s-cars] Reading Spark Plugs / WOT stumble, miss / dropped cylinder

Manuel Sanchez manuelsanchez at starpower.net
Mon Feb 9 17:44:31 PST 2009

Fellow S-Heads,

I tried the spritzing the ignition cables with a mist of water from a  
spray bottle at night tonight to see if there was any arcing. I had  
at least 3 different cables arcing to the valve cover and other  
nearby metal. That's in addition to the one cable I found to be bad  
enough that it drops a cylinder.

I didn't see any arcing before I sprayed the water mist, but I'm  
guessing there shouldn't be any arcing wet or dry, correct?

Matt, We use oxygenated fuels here in the winter. No other additives  
that I've introduced. Guess I'll need to wait for spring for a better  
color representation.



On Feb 9, 2009, at 5:08 PM, Matthew Russell wrote:

>> Message: 1
> *snip*
>> Bob,
>> Yes I was thinking the same thing (but hoping it was/is something
>> else). I have 034's High Output coil system, which I had hoped would
>> solve any coil & POS problems for years to come. The system only has
>> about 4,000 miles on it.
>> In my attempt to investigate the stumble / miss under load I decided
>> to inspect the plugs among other things (all plugs have the same
>> deposits (at least it's consistent). I found a few images on-line for
>> plugs, but my increasingly failing memory recalls that my old Toyota
>> manual had about 16 or so images of different residue conditions. It
>> went down into the detail level of describing if there was a little
>> too much timing advance or a little too much fuel, etc...  Closest
>> thing I've found on-line was some dragster discussion:
>> http://www.dragstuff.com/techarticles/plug-pictures.html
>> although I'm not sure if it's applicable to "non" dragster fueled
>> beasts, but somehow think the principles would be the same. I was
>> curious about the color as I had a few "yellow" specs on the
>> grounding straps of the plug and I was curious to find out what that
>> meant (still not sure). It's hard to see in the photo's(it's actually
>> not visible in the photo's), so I found it curious. Maybe my car is
>> producing GOLD! Mr Baloney will be happy to hear that. The ceramic
>> had a "pink" color which I haven't found a reference to yet. See them
>> here:
>> http://pictureposter.audiworld.com/73778/ngk_bkur6et_sparkplug.jpg
>> http://pictureposter.audiworld.com/73778/ngk_bkur6et_spark_plug_2.jpg
>> _manny
> Manny-
> another thing to keep in mind when reading spark plugs is that  
> different additives (ie, inj cleaner, octane boosters, etc) and  
> even different types of gas have different additives in them,  
> especially in those colder parts of the country this time of year.
> All this CAN change plug color and make it a bit harder to  
> determine exactly what/where the yellow color is coming from.
> Depending on your circumstances, it may mean absolutely nothing at  
> all.
> Sorry! 8-)
> -Matt, CO
> 92 s4

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