Please take a quick look at my #1 plug?

Jdub · 07-28-2013, 04:04 PM

This cylinder was one reason this car came to me very cheaply - ~145/150 comp and always a carboned and semi-oily plug from this cylinder. Note the small white dots - additive or ? Thanks in advance for your comments.

HawgRyder · HawgRyder's Garage

Those white spots could be aluminum...from the piston.
It could be from pre-ignition (knock)...if so...check your timing ...maybe the centrifical flyweights are stuck.
Bob

Porboynz · Porboynz's Garage

Agree, detonation. Ouch.

Steve@Rennsport · 07-28-2013, 11:07 PM

One cannot tell anything definitive about that plug without a close inspection with a strong magnifying glass so I'd caution anyone about making a premature conclusion.

You may be looking at fuel deposits, oil deposits (both look likely) and possibly aluminum, but one needs to look VERY closely at the center insulator to make that determination.

Jdub · 07-29-2013, 07:29 AM

Thanks guys. Here is the full spread of plugs:

manbridge 74 · 07-29-2013, 07:44 AM

What's the compression on the other holes?

I'd suggest a new plug in #1 and check it after a few miles.

KTL · 08-01-2013, 01:20 PM

All the rest look very good. Not too rich of an overall mixture (on the other 5) that's for sure.

Jdub · 08-01-2013, 02:06 PM

All of the other cylinders are healthy, at least 165+ - very consistent. It is only the #1 cylinder that is giving me this problem (clearly, looking at the 'plugs)!

My guess is a broken/land-bound oil control ring. If it were as easy as several doses of SeaFoam and some hot driving I would try that first. Otherwise, I just do not want to risk messing something up. Will take the advice and pull #1 'plug this weekend.

Car runs and pulls great, but I think I may be missing the full Porsche experience if I have one dud cylinder.

Hydrocket · Hydrocket's Garage

PM Sent

T77911S · 08-01-2013, 05:23 PM

wouldn't be timing, all plugs would look like that.

i would look at an injector problem or an air leak to the cause of what ever is going on.

do a leak down test

Jdub · 10-26-2013, 12:34 PM

Here is the plug for my #1 pulled after a little over 1K miles. Under a magnifying glass, it is a matt black over the entire plug, with some white at the tip of the electrode. What is interesting is that only one side of the plug, as split by the electrode, is actually slightly shiny and carboned - the other side of the electrode is a plain matt black with no buildup.

So presumably the plug happened to seat so that one side of the plug as divided by the electrode tells a different story than the other. A directional element to my over-carboned issue on #1?

I am about to drop some Techron/SeaFoam into the tank prior to my dumping for fresh Penn 20/50 with filter. Would love to unseat a stuck oil ring or ? with heat and time - a long run.

db_cooper · db_cooper's Garage

I presume the spark plug(s) are out of your 78 911? If it is a DME car let me know.

If it is a 78..I think your CIS injector on #1 is leaking, not atomizing, or just over spraying fuel.

Extra fuel (from to much fuel, leaking injector or a jet spray pattern) will wash the cylinder bore and dilute the protective film of oil on the bore..causing the rings to wear quickly..in the meantime..extra oil will work up into the combustion chamber.

Your #1 spark plug at 1000 miles looks like a fuel problem..the other five look Okay.

The first picture of the well worn plug looks like oil/fuel..the white flakes are "fuel salts" that being the additives..the heavy black/gray is old fuel and oil.

CIS injectors can be checked and cleaned if you can find an old school Porsche/Mercedes/Volvo shop with a hand pump CIS injector cleaner. Very similar to diesel injector cleaners. I haven't seen one around for years. Its worth a phone call or two.

Make a rig for checking your injectors in the meantime..something like this.