Missing zetec

[Bren]

My sister has a w plate fiesta with the 1.25 engine.

 

71k on the clock and in good condition.

 

It has developed what can be described a a "miss" every so often - car has had new plugs and coil pack.

 

It would appear to be worse when car is warm and there are no codes.

 

 

Any ideas?

[Junkman]

Change the plug leads. It'll run like new.

Also, did you check and correct the spark plug electrode gaps before they went in?

[sierraman]

Sometimes a knackered coil will damage the leads, I'd be inclined to change these also

[twosmoke300]

Is it on the right 5w30 oil ? Some Zetecs used to have sticky valves on the wrong lube

[Albert Ross]

These are prone to pressurised coolant leaking into the chamber where the spark plugs sit, through a core plug in the head. Before you have found the leak, the hot engine has evaporated the coolant, and cooled. Look for signs of pink powder near the spark plugs before walloping cash on electrical bits. It may be terminal. Top up the coolant and use a pressure tester to pre-pressurise the cooling system. Then run it up to hot to see if the misfire develops. It may be a red herring in your case, but it's a known fault.