misfiring cylinder

[drazyc]

hi all i have a peugeot 106 1991 is the carb style, my mechanicing knowledge is fair to good but im no expert.

ok heres the thing the car kept cutting out when you came to a stop, it was running fine on idle but didnt do it every time.

so i thought a good place to start would be to clean the dizzy cap, so i took it off, cleaned it with a bit of scotchbrite and wd 40 re assembled it all, and hey presto ran like a bag of nails.

so realised i had put the leads on in the incorrect order and resolved that thinking, great, thats all it was,

so i now have a fully functioning dizzy with the correct firing sequence 1342 but cylinder 3 is not firing AT ALL

i have tried swapping leads between 3 and 4 (i dont mean just on the plug i mean swapping the lead at the plug and at the dizzy) but it is still 3 which doesnt fire, which to me tells me that it cant be the lead because both leads can run cylinder 4, i have taken the lead off the dizzy whilst its running and the dizzy is sending a spark out to the lead.

so i though what the hell, i have gone to the local scrap yard and bought a "new" dizzy which is now fit and running but still not firing in the third cylinder

I AM AT A TOTAL LOSS AND HAVE NO IDEA WHAT TO DO NEXT!!

can some one please help??

[Mr Vegas]

Hi there,you say that you have spark coming out both leads 3&4 when you swap them over..how have you determined that cylinder 3 is not firing if you have decent spark to the cylinder like you say?

[drazyc]

yes it is definately cylinder 3 that refuses to fire, the engine can sustain combustion on 3 cylinders so while it is running i remove the lead from the dizzy that goes to the third cylinder and it makes no difference to the enigne at all. therefore definately cylinder 3

[Mr Vegas]

This is not always the case-if you remove the lead to the cylinder 3 and nothing happens that means that there isn't enough spark!However,if there is a faulty spark plug this would be the problem.

By removing each lead to one cylinder at a time there should be a noticeable running difference once the lead is removed,hence no spark and poor performance from that cylinder.
If you do this on leads 1,2&4 and there is runnning fault these leads are fine!If on lead 3 there is no difference the lead is worn or the spark to that lead isn't strong enough.(more likely the lead is faulty).

Any 4 cylinder can sustain combustion on 3 cylinders but there should be a noticeable running difference.My advice is to check the leads one by one as i wrote earlier.