well guys the falcon has started to form a miss again! now it had a miss and a flat spot about a year ago and a half ago. so replaced leads with motorcraft ones. spark plugs with genuine ford ones, fuel filter fuel pump and reco injectors. has had top end overhaul. head chemical cleaned ect ect ect. now about 3 months ago it formed a miss did all the checks screw driver onto the injectors ect. found to be cylinder 1 missing and spark plug had failed after about 3000 kms of use so i was confused :-S replaced with an ngk and was fine. now that fixed it. miss formed again so i thought hmm replace all spark plugs just in case. so did that and still have this miss. im not sure what to do now. im not 100% but 80% sure the coil was replaced with the leads and plugs. so was thinking how often should i replace the leads and coil. now i no the coil should ask for ages which im thinking it shouldnt have a problem but the leads have done at 10,000-15,000 kms :S anyhelp

well ive seen factory leads last over 10 years..
but it dont mean they all will.
most replacement leads give a 40,000km or 24 month warranty.
and i think the std plugs should be checked or replaced every 15-20,000km.
iridium plugs last from 80,000 to 100,000kms.

check that there is spark from the lead.
if so you might have a dead injector?
is it a constant miss or just at idle?

your miss could be from bad fuel??your injectors were cleaned but that dont mean that the injector cant fail. after all it is probably 12+ years old. a batch of bad fuel may have cloged one up again and your fuel filter wont stop 100% of the dirt..

on the other hand..
how many kms are on your engine??
does it use oil?
was the missing cyl plug oily or carbon black?
maybe,depending on kms you might have a cyl low on compression..

thanks alot for the reply.

cylinder plug looked perfectly fine. engine has done 240,000kms just did an oil and filter change yesterday. does not use oil. and last compression test came back fine. dont no the numbers as dad took it in. maybe it could be an injector again??? the miss is only at idel and seems to go away once accelerating maybe some au injectors will be put in i got these injectors off ebay.

Did you check the pcv??

whats pcv stand for? ive replaced a s**t load of sensors oxy, tps, map. might be onto the injector theory tho. is it known for the to "double up" (my term) as in - - - -- - - - -- - - - - -- - - - -- -- - ( douible -- represents double ticking) on cylinder 2 it does it. not in sync tho just random (with use of screwdriver on end of injector thats the ticking.

pcv= positive crank case vent..
(valve ontop of rocker cover)
but that wouldnt cause it to miss at idle..

if its got spark at the lead and the plug chek the injector..
when its idling take the injector plug off the missing cyl and see if it makes any difference.
if not i would say a weak,blocked or lazy injector??

Intake manifold gasket