While tinkering today, I decided to pull a plug for no reason other than to take a look. I'm not skilled at reading spark plugs but I looked at a lot of photos online. Based on the electrodes, I'd say that the AFR is reasonable. On the other hand, there is buildup around the threads that could suggest a rich condition. On balance, I think things are good but my confidence isn't high. Opinions are appreciated.

 

Slightly rich but not bad, it’s almost to tan. And these things run pig rich anyway stock

 

To me; it looks pretty good. It doesn't strike me as running lean.
I guessing (like my Mini) the black carbon is due to running rich at first idle.
I'm also anxious to hear what the more seasoned expert opinions have to say.
As I am not.

 

In order to accurately "read" plugs, you need to drive the vehicle for an extended period of time at highway speeds, then quickly come to a stop, shut the ignition off and let the engine cool before pulling the plugs.

 

The plug in your pic the tip looks clean. That suggests the mixture is fine.

Are those the plugs recommended by MINI?

One has to be careful using non factory recommended plugs. A number of car engines -- my 2002 Boxster was the first time I encountered this -- are fitted with extended tip plugs. These run hot at low to moderate throttle which keeps the tip clean. But at larger throttle openings this tends to cool the tip.

As a result the plugs stay clean and work.

Just to show you what I'm talking about a pic of a new plug and an old plug from my Boxster. Old plugs were due to be changed at 60K miles.




After new plugs fitted I noticed no change in engine behavior/performance. This is good actually. It is a sign the old plugs were still doing a good job. The last thing one wants to do is run the plugs to the point the combustion is affected and among other negatives deposits build up.

 

Thanks for the replies, guys. @RockC The plugs are one-step colder NGKs. My car has the JCW kit so I'm pretty sure these are recommended.

 

Based on the condition of the tip and ground electrodes the mixture/plug heat range appear to be good.

The bit of carbon deposits on the exposed metal of the plug threads I believe arises from that metal running cold (relatively speaking) due to good heat transfer from the plug to the head. If you were to pull the plugs after a good run at highway speed those deposits might be reduced even gone.