Hello,

I bought a 1.4 Fiesta Zetec yesterday from a car auction as a cheap run around. Im not to hot when it comes to Fords but know my way around an engine.

Its done 80k miles and seems to be all OK apart from a low rev misfire. At idle it is a little lumpy and when the accellerator is slowly applied the misfire seems to get worse up to around 2k and the car judders. Over 2k it dont seem as bad. When driving you can feel the missfire all the time if you look for it, but at lower revs it is more noticable. Pulling away can be a bit of a pain and requires more revs than it should.

I removed the leads one by one with the engine running and one didnt make any difference. It the 3rd cylinder from the left. I took out the spark plug and it was black and wet. To check the plug, I cleaned it up and put the wet plug in another cylinder and the good plug from that cylinder into the cylinder that wasnt firing. The wet plug fired fine in the good cylinder, but the good plug in the misfiring cylinder didnt make any difference. To test the leads I changed the leads over which again didnt make any difference. I thought that the injector may be faulty so swapped them, again, no difference.

I am now worried that I have a problem with the valves or rings on one cylinder. I will do a compression check if I get time today on all the cylinders.

I have read that the coil pack can cause a low rev misfire, but when I tested the leads yesterday there was a spark jumping between each lead and the coil pack when I removed them one by one so assumed the coil pack was ok?

Can anyone suggest anything else it could be? Im worried I have bought a lemon

Thanks,
Mabbo