Plug reading

Aug 26, 2004 4 Replies

What does it means that a fine black powder builds up fast on my plugs and what should I do ? Thanks in advance


Sorry, it's a Nissan Sunny 1992 petrol ignition

A light black powder or soot buildup on the plugs is carbon fouling. It means you need what used to be called a tune up.

heavy black powdery build up on the plugs mean in is running rich (excessive fuel mixture)

could be any number of things causing it.

If it's a carburettor model then it could be the choke not releasing after the warm-up period, or a very dirty air filter, or a blocked small bore rubber pipe at the carburettor. Or you only use it for 1 mile journeys and there's nothing wrong with it that a 30 mile blast wouldn't sort out.

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