jerome951

Well,

Found the cause of my intermittant miss. Pulled the plugs (Bosch copper) and found one of the center electrodes is missing. Couldn't see the trode on the piston top looking through the spark plug hole so I don't know where it went.

Should I be worried? Car seems to run fine now, has not lost power, and no unusual noises. Not sure if the electrode can wedge between the piston and bore and cause issues or if it's big enough to cause any compressor damage if it gets into the turbo.

Thoughts, warnings, things to check without pulling the head? I might have my shop check the cylinder w/ their borescope for piece of mind.

Thanks,
Jerome

LFA951

I had the same plugs before, I'm glad I switched to NGKs

special tool

got a pic of the plug?
copper only???

you won't have to worry about it getting into the compresssor, just cylinder/turbine

Chris White

Loosing electrodes is ‘generally’ a sign of detonation….be careful!

User 41221

I've seen that do some MASSIVE damage to a head and cylinder walls before. I've also seen them have zero effect (I'm assuming the electrode bounced out the exhaust valve opening almost immediately in that case). I'd suggest a compression test to put your mind at ease, but if its running okay and not smoking or using oil, I wouldn't worry too much about it.

Regards,

jerome951

Thanks guys,

No pic yet but will try to get one today and post.

Chris, I hope it's not detonation as everything is stock on the motor. Dyno run this past summer showed its fat, fat, fat... All plugs showed pretty rich, including this one.

I think I'll have a compression test done just to be sure. I'd rather pull the motor in the winter if necessary rather than wait and possibly miss valuable track time. Season starts in March. ;-)

jerome951

Here are some pics of all the plugs and the offending one.

Correction to my first post. Plugs are Bosch silvers, not copper. 7 heat range.

The center electrode is missing down inside the insulator but I can't tell how far. Really can't tell if it melted out or broke off.

Hopefully the broken bis were blown out of the cylinder without damaging anything. Since it's running fine I'll assume no major damage was done.

Bri Bro

It broke, no sign of detonation. It appears you are running a little rich if anything. If the car is running like before this happened, I wouldn't even give it another thought.

2bridges

saw a similar condition (not porsche, but 4cly turbo) - also burned a hole in top of piston. was due to very lean condition under boost.

I would keep real close check on the new plug. If you see signs of melting, better figure it out before driving (especially under boost)

HIGHBOOST

Jerome, sorry to hijack the thread.....What were your stock numbers? HP/TQ

jerome951

I had a dyno run last summer that showed the car to be rich at WOT across the RPM range, and especially so at 5k and above (which is where the car normally lives as it's a track machine). ICV is gone so adds some richness on cold starts, which it's had a few of recently.

My results on a Mustang dyno (motor is stock, 116k miles, only upgrade is LR 3" exhaust and Magnaflow w/ wastegate atm dump) were 223 hp and 232 tq at the wheels.

2Bridges, I'll certainly keep an eye on the new plug to make sure no problems appear.

A.Wayne

I must say , i have never seen that happen to a spark plug before , without losing the ceramic, NEVER and i have seen many !. You are lucky as if the ceramic had fallen off , you would have the possibility of some damage .

1. Based on the accuracy of the pics ( not in my hand , under a microscope, etc. ) your car is burning oil , the color is from the oil .

2. Oil being in the cylinder will cause detonation .
3. Number 7 Bosch are too hot a plug. use 6 .
4. If you switch to NGK , use a no 7 , copper plug .

Your car must smoke a bit , accel /decel

jerome951

Thanks A. Wayne,

I do get some oil in the intake tract, especially around the throttlebody. I run about .5-1 qt above full on the track to reduce the risk of oil starvation so I think it's coming from the oil mist separator. Turbo outlet is dry do I don't think it's leaking through the turbo.

However, the car doesn't smoke except from a rich mixture (and the occasional fireball). I've seen video of my car from someone trailing me on the track and there is no oil smoke. None on cold starts, either. I am switching to a cooler plug from other advice, but thanks for confirming.

Mike Buck

yikes! i would run a heat range 3. Should run you about $12 each. ask ivan to get them for you

A.Wayne

Did the plug fail right after the track event or at the track event ?
Do you have a blowoff valve , vented to atmo ?