I have a bone stock 87 TII and when i pulled the plugs before i drove it home from denver they looked normal as far as coloration (tan, stain-white). after the 600 mi trip back from denver and a little spirited driving arround here i pull them and they are all pretty dark. The Trailings are at least a shade darker than the leading. I dont know if maybe its running lean from a fouled injector or if its running rich? any ideas would be appreciated.

 

bump

 

if theyre dark, you are running rich this could be caused by a bunch of things tho. did you notice a lck of power. did anything else change on the car besides the plugs?

 

I don't think you want them white. I beleive that is an indicator of a lean condition. That is one thing you don't want to be. pre-ignition occurs with too lean a mixture and that causes damage in most cases resulting in an engine rebuild being the cure.

 

you definetly dont want them bone white but they shouldnt be dark/brown either. idealy a light tan with minimal scale/ash buildup on the electrode. my car tends to run rich and my plugs still look a deep tan. if your plugs are darker than that something has gone wrong. were they wet when you pulled them? hard staring? maybe a leaky injector. is it doing it on both rotors?

 

my plugs are dark. Always. The electrode is an lighter color though. But I know I am running pig rich. But I haven't been able to go to the dyno yet. Besides I wouldn't know what to tune for.

 

white is bad because when anitfreeze is burned it turns white but then again it may be from running a little lean.

 

What does it mean when spark plugs are unevenly shaded? For example when half a side of the plug is darker than the other?

 

I havent checked my plugs since but when i first pulled them the front were clean and soaked with gas while the back were black and dry. whats up with that?