I just changed the spark plugs and number 2 and 3 (counting from the front) had oil on the threads. There is also some corrsion which is worst on number 4 and there was also some white'ish dust on the outside of the number 4 coil rubber sleeve. All the tips look ok to me.

From what I understand, the oil is probably due to a leaking valve cover gasket but what about the corrosion - anything to worry about?

- Tom

#1


#2


#3


#4

 

Looks like oil all-around with, maybe, some overzealous engine washing.

I don't like the looks of #4. Are those specks on the tip insulator? If so, that plug is overheating. Could lead to pre-ignition.

 

Thanks. I did flog it recently at a track day and it had a tendency to overheat until I started running with the heater on max.

Close-ups of #4. What do you reckon?

 

if it looks pitted/sandblasted you got some detonation goin on

 

Agree. Don't like that at all.

Looks like you could really use a coolant reroute along with a less aggressive tune.

 

Did what I should have done to begin with: Make a proper photo comparison.

So, I'll be retarding the ignition a few degrees for now. Then get a new VC gasket and once I go FI, I better add the cooling reroute. Thanks guys.

 

WHOA. Go to colder plugs stat. What afr are you running? I looks kind of lean but that could just be from the plugs getting hot and burning the carbon off.

 

Hellz yeah... Looks too hot... The corrosion is the least of your worries, as its probably just from water in the plug wells... But those plugs look hot.

 

Looking at this, it doesn't look completely wrong to me (or am I missing something?: NGK Spark Plugs USA

However, here's my afr and ignition settings:

 

What I'm seeing on #4 is evidence of overheating and det. It's those dark specs on the insulator along with what looks like slight insulator damage that I don't like. Look at picture #4 on the NGK website.

As for fuel and spark tables:

1. On fuel, you would like to get to 12.5:1 once you get above 85kPa. That will give you more power and cool things off a bit. Remember that the AFR table is a secondary control. It is only used when you are running in closed loop mode -- and only with limited authority (I only allow 5% deviation away from the VE table on mine). Most of the time on track you'll only be running off the VE table -- so you have to make sure it is well tuned (autotune or VE Analyzer).

2. Your spark table looks 2-3° too advanced across the board. Did you tune spark on a dyno? Did you use det cans and were you hot? Reducing the timing will help you cool things off.

If you spend a lot of time on track, a reroute is a good thing to do even if you're still NA. Without a reroute, the #4 cylinder runs quite a bit hotter than the others -- leading to the issues you're seeing here.

 

Thanks Rick,

I can totally see what you mean about #4 and I will definitely run a milder tune - especially since I'm usually running RON99 but risk ending up somewhere with only access to lower octane fuel.

What I didn't understand was the other comments about all of the plugs looking like they were running hot. To me they look fine. Especially since they are around 3 years/40,000 KM old. But I'm close to clueless on spark plugs so I may be missing something.

- Tom

EDIT: By the way, my fuel table is thoroughly tuned with VEAL based on the above AFR table. The ignition map has not been dyno tuned but I kept an eye on knock detection back when I started running it.