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Really odd..... I did my plugs today.... I flashed a light into the holes as I always do... not sure why I do this but hey, how often to you get to look in there? One plug hole had a bunch of black soot on the bottom half of the hole down at the threads. It wasn't a dusting... it was a pile of soot. So I inserted a peice of clear tubing I had taped to the end of a shop vac attachment... I had this laying around.... and it sucked it right out.... so it was not oil or stuck to the tube.... but jet black powder. I could not touch it as it went straight into the vac..... I suspect it "came loose" from the plug seal as I loosened it but am not sure about this.... it was on the bottom half of the tube and the rest of the tube was shiny... as was all the other tubes.
What was this? Why was it there?
BTW, 22 ft lbs seems like not much torque..... the old plugs always come right out nicely..... this is an easy job once you get in there.
Peace
Bruce in Philly
Last edited by Bruce In Philly; 11-23-2017 at 04:17 PM.
Hmmm....had a very similar condition when I had a Mini. About 5k miles later I blew a valve. Upon disassembly, a valve seat was burned and carbon started to build up on it until the valve couldn’t seat all the way because the soot built up between the seat and the valve.
Had the whole head resurfaced and all new valves/seats installed.
Hope the soot is where the similarity ends. Would like to hear better Porsche related facts from better informed peeps.
How did the spark plug in that hole look. Same black powder soot? Which cylinder?
If it's dry powder which it sounds like it was if it sucked out, could just be a overly rich air/fuel mixture. Excessive idleing, driving at low rpm, etc... can cause this.
Just give her the good old itailion tune up and wind it out a few times...
Enjoy your turkey day and worry about this tomorrow.
I don't know which plug was in the offending hole, but one plug was blacker than the others. Notice the fourth plug from the left has a black ring on the threads? Odd. It is clear one plug or cylindar was not behaving like the others. I tapped the plugs on the typing paper (who uses that term anymore!) and out dropped that carbon dust. Interesting how combustion migrated up into the threads. I think Mr. Platinum has it right..... driving at low RPM etc...... For the last 8 months, I have just been driving my car for a 12 minute drive to the train station and back..... the oil temp needle barely moves by the time I get there ..... I keep revs below 3500 as it warms. Italian tuneup on the books..... but why some plugs more than others and one that was worse? Maybe I just didn't torque it down all the way the last time?
Techron next fill up... maybe a few treatments in a row.
Might have been interesting to compression test that cylinder against a couple others while you were in there doing plugs.
I thought the same thing.... don't have the tools though. Another thing struck me.... would the dealer have discovered this and then did anything about it? Is it typical or standard dealer procedure to inspect the hole and plug tips?
BTW, I kept the plugs from my last two replacements..... they all looked consitant and "smoother" on the tips and no black... just cinnamon..... I wonder if something is just degrading in the engine or was it the short everyday trips..... my usage prior to the last 8 months was heavy highway and high RPMs... fun driving. Now it is just a grocery getter.
It looks like some of the threads on more than one plug is kind of dark. You could maintain your driving habits and pull it again in a couple thousand miles. Sure seams like the rich burn from short trips. If it shows anymore dust after that put in another new one and then head up to the country more and drive the snot out of it.See if the problem clears.
They look fine to me. Probably just carbon build up. Typical for DFI engines. There’s a chance that plug wasn’t fully seated too. As for the torque yes it’s lower than you might think. There’s a crush washer that deforms to make a seal. If you ever remove and reinstall a plug the torque spec is higher for the second tightening.
The plug shot of just the two....plug on the right, the electrode diameter looks larger than the one on the left. Electrodes wear down in diameter as that’s where the spark is drawn to the ground. The plug on the right also has a black sheen on the plug collar as well....my thought is a weak coil perhaps.
It would have been nice to do a compression check (I do a check with every plug change)...it would rule out the more ominous issues.
Just to be sure, check the air pressure in your tires...it has nothing to do with the soot but you’ll feel better that something makes sense today.
Time to check the Turkey...have a great Thanksgiving, it’s gonna be 93F here today.
FWIW, a friend had his 9A1 scoped and the valves were completely clean. I have yet to see evidence of problems in these motors.
But 8 months of 12 minute drives could have an affect.
You're in rough country for salt and corrosion. The suggestion of a weak coil makes sense to me.
Since getting intimate with my table saw I've been waiting to get feeling in my fingers. That's a weak excuse for having fresh plugs in my toolbox for the last 25K miles. My plugs will have 60K plus miles on them when I change them tomorrow. While my motor is fresher than yours (only 105K) it still may be reflective. I'll post results.
FWIW, a friend had his 9A1 scoped and the valves were completely clean. I have yet to see evidence of problems in these motors.
But 8 months of 12 minute drives could have an affect.
You're in rough country for salt and corrosion. The suggestion of a weak coil makes sense to me.
Since getting intimate with my table saw I've been waiting to get feeling in my fingers. That's a weak excuse for having fresh plugs in my toolbox for the last 25K miles. My plugs will have 60K plus miles on them when I change them tomorrow. While my motor is fresher than yours (only 105K) it still may be reflective. I'll post results.
Have a great Thanksgiving ... Wayne
You too man!
Ok you got me excited... Three things.... Peak in the holes to check for black residue,. But tap the plugs on a white sheet like I did.... Then cut em up!!! Gotta see the gory details.
FWIW, my plug #3 was a little bit sootier that the others. ( The 2009 C2S engine had 34 K on it and about 15K on the plugs ) The Blackstone oil analysis has always been clean with no fuel contamination etc )
I thought the same thing.... don't have the tools though. Another thing struck me.... would the dealer have discovered this and then did anything about it? Is it typical or standard dealer procedure to inspect the hole and plug tips?
BTW, I kept the plugs from my last two replacements..... they all looked consitant and "smoother" on the tips and no black... just cinnamon..... I wonder if something is just degrading in the engine or was it the short everyday trips..... my usage prior to the last 8 months was heavy highway and high RPMs... fun driving. Now it is just a grocery getter.
Peace
Bruce in Philly
Plugs look fine. Well, the discoloration is quite a bit higher up the threads than I am used to seeing. Did you run the plugs "too long"?
Anyhow, a bit of variabilty is normal. IOWs, the plugs won't look the same.
Absent any untoward engine behavior, or a CEL, there's no need for a compression test. The DME constantly monitors the output of each cylinder. If it gets too low (or too high) a misfire error code is logged and the CEL turned on.
The short trip usage accounts for the build up of carbon/soot. Even though I use my cars for work commute which has me driving 30 miles each way a day the times I drive my cars longer distances: ~50 miles or more; the engines run noticably better. So it is not surprising that your usage has the engine showing signs of accumulating combustion chamber deposits.
(In some cases the usage leads to a heavy build up of deposits. The car is parked. Over time the deposit layer loosens and then the next time the engine is started a piece of this falls loose in the combustion chamber. This can momentarily cause misfires, or even a "ticking" noise if some of the deposit material gets caught between a valve and valve seat.)
You can use Techron if you want. But a good long drive -- ~50 miles or so -- at freeway speed is all the engine needs. 'course, if you resume the short trip usage the engine deposit build up also resumes.
A problem with Techron is it increases oil contamination and to "combat" this the general recommendation is to if one uses Techron to after almost alll of the gasoline with Techron added is used up to then change the oil.
Might mention after a tank or two of Chevron Supreme (with Techron) my Boxster engine was running noticeably better even though my usage stayed the same after I switched from Shell V-Power to Chevron Surpreme. The Techron on the Chevron gasoline was the difference. So you can get the benefit of Techon without having to add any to the fuel tank if you have a Chevron station handy. Just fill up the gasoline tank with Chevron Supreme once in a while.
11-23-2017, 12:19 AM
Black soot in a spark plug hole... what is this?
