WTF happened to my spark plugs?
 

This branches from the other thread I had.

Info: The night before the car was running amazingly well, pulling hard all the way to redline. The next morning went to start her up while it was like 40F degrees outside, I never drive the car when it's that cold out. It started right up and immediately the exhaust tone sounded dramatically different than normal. I had to move the car and when doing so it had almost no power at all. Shut her down a few min later and went to work. Came back later and it was still acting the same way. I feared the cold start had chipped a seal or something, but then out of nowhere the idle bounces around and the car starts running great. About 3min later the problems come back. The next day the car wouldn't start at all. I tested everything, including compression which was perfect on all rotor faces. The main culprit turned out to be a bad plug wire and these plugs of course.

My question is what happened to them? The whole inner electrode is gone from both the leading plugs. These are(were) the 10.5 NGK Racing plugs.
...and yeah, you might be able to tell I am running a little rich. My fuel pressure being 50psi at idle is a-whole-nother problem though. :)



http://myweb.cableone.net/wrex/images/L_front.JPG

http://myweb.cableone.net/wrex/images/L_rear.JPG

a more disturbing question is: if the center electrode isnt there, where did it go?

Preignition, detonation, and/or too hot of a plug (heat range) will all cause this. (I assuming that these plugs aren't that old.) One clue here is that the wire(s) probably failed due to the increased voltage requirement and stress placed on them by the rather large gap (lol) that your plugs seem to have. I suspect that they have been deteriorating for some time, until the ignition could no longer fire them.

Also remember that the leading plugs, wires and coil are all effectively in series.

what kind of plugs are those???

How long did you drive those plugs?

We just had them out less than a month ago and cleaned them(using that plug cleaner air tool). They were fine then, and like I said the car was running amazingly the night before.

Also, running an MSD 6A amp and TII coils.

Before the electrode dissappeared, I've had the same plugs for about a year(about 1k miles). They foul quick so I had cleaned them twice so far. I planned on not cleaning them a third time and just buying new ones. Maybe the two cleanings were too much for them? Gotham cleaned them the last time.

Are you running both plugs off one leading coil?

What setup are you running? It looks to me like you have big problems. Why are you running a MSD amp, racing plugs and so damn rich? Fix your setup and I bet this problem will solve itself.

What problem? Yeah the car is running rich, the last person to touch the PFC maps was Steve Kan, but he did not do a full tune just a rather conservative one. These plugs foul out relativly quick especially since I had only really driven the car in town.

Well, just got off the phone with the shop(Pettit) and they said cleaning the plugs will cause this to happen. They said it was pretty common on the Greddy Racing plugs, but the NGK Racing plugs hold up longer. I had the Greddy plugs. Essentially cleaning them too much wore off the coating and the electrode melted. No real damage, just time to shell out the money for some new plugs. I went ahead and threw in 9's all the way around. No sense in continuing to foul out $35 racing plugs. She will get a full tune in January; will finally get to see how this car really performs. :cool: