My girlfriends brother has a 1.2 2004 petrol fiesta, and yesterday was juddering and lacking power when driving it. I serviced it with him, and we changed the spark plugs but now the car is worse and engine management light is on.

The same thing happened 2 years ago when the garage that was servicing it had not changed the spark plugs in 6 years and the firing end blew off, so I changed them but the problems it had created had ruined the coil pack. He thinks it feels the same as the time that happened 2 years ago.

The plugs were excessively gapped so I am wondering if the coil pack has burnt out again.

Has anyone got any other suggestions. I am also planning on changing the leads as well, to ensure everything has some life left in it.

Any help much appreciated.

Jordan