help ! fouled spark plug
 

After two inches of snow on top of warm engine i wrongly diagnosed my lack of power and rough running as water shorting out an HT lead, after a short run to heat things up and dry them out i soon realised this was not going to be as simple.

With the engine running i pulled each ht lead in turn until i found the malfuctioning cylinder, i removed the plug to find it covered in black soot and carbon deposits - just like the coloured photo's in the haynes manuals that i remember from my teens.

However i cant remember which symtom should cause this and why in only one cylinder?, do i have real problems ahead.

I also need some help as to which rating of plugs to replace with as i did not get a manual when i bought the car 8 weeks and 5500 miles ago.

The car was supposedly serviced when i bought it from the dealer and it did have clean oil and a shiny new oil filter but im wondering if that was about the sum total of the service.

Any help you guys can give would be much appreciated.

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mike 87 coupe'

Mike,

There are a couple of possiblities. One is an 'open' igniton wire. Check the resistance of the wire to the fouled plug with a digital multimeter for a steady resistance value ... it should be between 3000 and 5000 Ohms. If the reading is not steady or it reads 'open' ... that is your problem!

The other possibility is an injector that is 'stuck' open or dirty.

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Warren Hall
1973 911S Targa

will check the ht lead tomorrow.

Which plugs should i get as replacements?

Mike,

NGKs are good - BP-6ES

Also, the copper-core Bosch WR7DC

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Warren Hall
1973 911S Targa

what is the plug gap setting (need to get a manual i know)