My car has been misfiring pretty badly since about 2 weeks ago after hitting a puddle at the side of the road (may have happened earlier in the drive but this is when I noticed it). Since then I've had the coil pack, leads and spark plugs changed for new ones and the problem went away for a day or two and it's back again. 

Misfires worst when I'm in second / third and put the foot down, it's as if it's stuttering  

It's a 53 plate 5 door 1.4 petrol fiesta.

Could there be a problem with the coil pack or plugs? or is there anything else I should try? any help appreciated

9 hours ago, MichaelMct said:

My car has been misfiring pretty badly since about 2 weeks ago after hitting a puddle at the side of the road (may have happened earlier in the drive but this is when I noticed it). Since then I've had the coil pack, leads and spark plugs changed for new ones and the problem went away for a day or two and it's back again. 

Misfires worst when I'm in second / third and put the foot down, it's as if it's stuttering  

It's a 53 plate 5 door 1.4 petrol fiesta.

Could there be a problem with the coil pack or plugs? or is there anything else I should try? any help appreciated

Look down into the spark plug  'wells' and check there isn't any water in them. It's well documented about water getting into the 'wells' from the washer jets causing plugs/coils to blow. Had it on my own 2004 mk6 fiesta a few years after buying it.

33 minutes ago, Russ said:

Look down into the spark plug  'wells' and check there isn't any water in them. It's well documented about water getting into the 'wells' from the washer jets causing plugs/coils to blow. Had it on my own 2004 mk6 fiesta a few years after buying it.

I'll have a look today, thanks. How did you fix this? 

35 minutes ago, MichaelMct said:

I'll have a look today, thanks. How did you fix this? 

If the water is coming from the washer jets just remove them, clean the area on the bonnet that they're situated in then put a light covering of silicon sealant on the underside of the washer jet then reseat them on the bonnet (clean off any excess silicon). To make 100% sure mine were sealed I also put silicon on the underside area from inside the bonnet. 

5 hours ago, Russ said:

If the water is coming from the washer jets just remove them, clean the area on the bonnet that they're situated in then put a light covering of silicon sealant on the underside of the washer jet then reseat them on the bonnet (clean off any excess silicon). To make 100% sure mine were sealed I also put silicon on the underside area from inside the bonnet. 

Done this, thanks for the help. Now all I need to do is dry out the water from inside the area where the spark plugs are? just a heat gun and dry it out thoroughly? 

53 minutes ago, MichaelMct said:

Done this, thanks for the help. Now all I need to do is dry out the water from inside the area where the spark plugs are? just a heat gun and dry it out thoroughly? 

You can dry the area out using a towel or paper towel by pushing a bit down the port & letting it soak some water up. Wring it out and repeat until u get most of the water out then blast a hairdryer into the area to dry up the rest. This will save removing the cam cover but will obviously take longer to dry the port out. Once the area is dry check it for a few days to make sure a core plug isn't leaking coolant into the port.