wanted to change out the plugs, only to find that I had 2 Denso and 2 NGK's ..all 4 plugs are correct for the 1990 loyale..installed on each side 1 ngk and 1 denso and then drove 1 hr ...out of curiosity I pulled the plugs and the denso were grayish in color through out while the ngk's were more whiteish with a greenish colored ground strap..switched them around and drove another 1/2 hr..pulled the plugs once more..basically no change to the plugs except that the green color was a little darker ..spark plug charts make no mention of this greenish tint..any ideas..timing, or are the plugs to hot??

Not sure about your case, but green usually indicates oxidation of copper. If you want a reliable indication of your cars fuel/air ratio, clean the plugs and do a full throttle run in 3rd and kill the engine before lifting your foot off the pedal.

Better yet, I would replace them before testing again. Take note of which cylinder you pulled the plug from that has the discoloration if it returns. A compression check will rule out a cracked head.

Or better yet..... a leak down test would give you a better indication of your cylender's status including valve leaks.

Has you car taken a recent Mexican vacation?

 

I`ve never seen it, but apparently lead fouling can be greenish.

http://www.circletrack.com/enginetech/ctrp_0403_spark_plug_tuning/reading.html

wanted to change out the plugs, only to find that I had 2 Denso and 2 NGK's ..all 4 plugs are correct for the 1990 loyale..installed on each side 1 ngk and 1 denso and then drove 1 hr ...out of curiosity I pulled the plugs and the denso were grayish in color through out while the ngk's were more whiteish with a greenish colored ground strap..switched them around and drove another 1/2 hr..pulled the plugs once more..basically no change to the plugs except that the green color was a little darker ..spark plug charts make no mention of this greenish tint..any ideas..timing, or are the plugs to hot??

 

 

Hpw old are the spark plug wires

Hpw old are the spark plug wires

Plug wires are new and the spark plugs never used before..