Greenish Yellow Discharge... I mean deposit!

[motorhead]

What the hell is this green crap on the electrode?

The plugs are 42,000km (26,000 mile) NGK TR6s on the right, they came out of our 160,000km (100,000 mile) LS2, and the stock 118,000km (73,000 mile) Delco Platinums on the left.  Both plugs are out of the same cylinder (#7 - yes, I keep and number my plugs for future reference).  All eight NGKs look the same within a degree of each other.  Clearly something changed in the last two years (yes, there were modifications), I am leaning toward fuel.  We've almost exclusively used a single brand since moving up to Ottawa (some might call it a discount premium (91 octane)) and it may be the source of the discolouration .

There is nothing on these sites that gives me any indication of what I am looking at:

http://www.4secondsflat.com/Spark_plug_reading.html
http://www.jetsrus.com/FAQs/FAQ_spark_plugs.htm
http://honda-tech.com/showthread.php?t=3063102

The fuel trims are within spec (+/- 5%) and the timing has been adjusted to remove any knock retard.  There is the possibility the O2 sensors will need replacing soon as they are 6 years old (original) and the MAF needs cleaning which could explain the carbon tracing down the insulator; that and the plugs were left in 6,000miles too long so they may have degraded badly.

Thoughts?

[Steve Wood]

antifreeze?

[motorhead]

Nope.  It has Dexcool in it.

Someone put me on to this:

http://www.camaroz28.com/forums/adva...g-tips-608199/

http://m.ls1tech.com/forums/showthread.php?t=292801

This tells me that my plugs are wrong in both directions (hot/cold):
http://grounds-mag.com/mag/grounds_maintenance_servicing_spark_plugs/

One sign of heat used by some professionals is electrode color. Many--but not all--spark-plug electrodes have an alloy composition that will oxidize green when subjected to high temperatures (see Photo 2, again). This nickel oxide on the center wire and sidewire would show up first at the tip of the electrode--the hottest part--and progress from there, depending on temperature. Excessive green oxide may signal it's time to change to a colder plug. Several causes of high spark-plug temperature are described in the boxed information at left. The main thing to keep in mind here is that not all electrodes oxidize (turn green) at the same rate, if at all. Therefore, your best bet is to turn to a technician with experience reading plugs.

If the plug looks dark or sooty around the insulator tip (see Photo 3, page 76), the plug is not running hot enough to burn off carbon deposits. The engine may have been idled excessively, it may be running too cool, the air/fuel mixture may be too rich, or you may need a hotter plug.

[$1987 GN$]

I have seen that from weird fuel mixes.

AJ___