I just pulled my very low mileage spark plugs because I am giving a different plug a test run and I am a little worried about the color. The plugs have less than 1k miles on them, and my car is running alot leaner than a stock s5 fc, but the leadings were dark EVIL black and the trailings were a reddish brown. That seems like signs of richness but thats practically impossible. Any other ideas?

 

Sounds about normal to me...

If it's running lean (how can you tell?), then the plugs would not be "black" at all...


-Ted

 

Well the car has had the safcii turned down -8% since ive got it and Ive turned it down more than double that in some areas to the point that I have practically no backfiring and a noticeable increase in mileage. I havent gotten it on the dyno/wideband yet but that sounds lean.

 

Non-turbos run very rich.
Typical S-AFC settings are around -15%, so you're still running rich.
Spark plugs don't lie - the color says it's running slightly rich to normal.


-Ted

 

This is interesting. I said the car came w/ -8% I am currently ranging from -14 to -18 above 4k. I guess I need to get on that wideband asap. Thanks Ted.