Can anyone of you experienced people assist misfire cylinder 1 I’ve replaced coil pack and all 4 plugs on my 2014 Ford focus st 2.0 eco boost can ran perfectly fine yesterday then parked it up for an hour and a half went out in the car started to feel idle running lumpy then engine management light came on so changed pats as listed above even stripped the injectors and swapped them around still no joy does anyone have any ideas 

Did the misfire start after changing the parts?  Or you've changed them to try and fix?

If it was before changing parts then I would have compression test done before going any further.

Done compression test on cylinder one 50 psi looks like it’s a damaged valve or the rings have gone on cylinder one cylinder 2  180 psi it’s only done 65000 miles don’t know what the repair bill will be ? 

21 hours ago, TomsFocus said:

Did the misfire start after changing the parts?  Or you've changed them to try and fix?

If it was before changing parts then I would have compression test done before going any further.

Miss fire started we was out in the car it run faultless then parked up for an hour and a half then went out and noticed idle was lumpy then coming back started misfiring and the milf light came on put it on the computer and stated misfire cylinder 1 so I changed all plugs and coil pack switched over injectors and still the same 

Is it likely to be more inlet valve or rings anyone who’s had the same issue please feel free to advise 

Sudden loss of compression is usually caused by a cracked/broken piston on these engines. Just search the internet and you will find plenty examples.

Further investigation/disassembly is required but it is highly likely that you are facing a full engine rebuild.

I’m thinking exactly the same or failed ring lands been looking at forged pistons and con rods but don’t know which ones to buy 

6 hours ago, Paul feza said:

I’m thinking exactly the same or failed ring lands been looking at forged pistons and con rods but don’t know which ones to buy 

I think you would be better off stripping it down to see what's actually wrong before ordering parts.

Yes it’s going in on Tuesday going to do a head gasket test to as it’s producing white smoke so will get that pressure test done if it’s the head and not the piston I will have all the valves pulled especially intake and have the valves cleaned  I thinking the worse to be honest best getting prepared 

We’ll head gasket looking ok but had the bore scope down on cylinder 1 not looking good for piston 1 thinking forged as these standard postons are weak so I’m thinking forged what’s anybody’s ideas of make of forged ?