right i have a 2005 fiesta st150 problem started on way home from work pulled up too a set off traffic light sand all of a sudden started missing thought nowt of it at first thought it might just need a set off new plugs.There is no engine light on so il tell you what ive done so far!!!

New coil pack
New iridium plugs
Checked plug gap 1.3mm
Ht leads checked
Cleaned map sensor
Took off throttle body cleaned
Done compression test (perfect)
Checked all fluid levels
Checked and cleaned egr valve
Checked all vacuum lines/breather

and its still missing still no engine light on what else could it be and has any one else had same problem


i no the duratec as a pcv valve behind the inlet manifold could this be at fault or could cat of collapsed/1 of the 2 lamba sensors be at fault its strange cos if there were the engine light one be on

 

are they not individual coils, if so did you replace all 4 ?

 

1 coil pack on them not a coil on plug set up

 

Did you use NGK plugs and Ford Coil Pack? These engines and the zetecs prior are very sensitive to Coils, leads and plugs. It could well be a lead breaking down causing your issue.

 

I will change leads on it see what that dose and yes got bosch coil pack but denso iridium plugs
But the other plugs were ngk and swaped them over and still same miss fire

 

did you find the problem as mine has start doing this to