Quote Originally Posted by David View Post
After you try the injector move that Steve sensibly suggested, if that doesn't work, check the connection to the COP on #5. MSD's can be a tighter fit than the OEM COP's and not properly pushed home. Examine the COP for dampness (on and in the tube part), and ensure that the contact spring is properly seating on the spark plug terminal. Finally swap #5 COP and another in the same way as you did the injector. Peer down the plug hole and see if the plug insulator ceramic looks discolored or "different" to the others.

David
After I replaced all my plugs recently after a persistent low revs misfire, old 206 was initially worse. The misfire was more frequent, especially under a light load at low revs. Then one day I was driving in normal traffic when the car gave a little surge as if someone had turned on a "go faster" switch and the misfire went away. Now the car goes like a rocket! I'm still looking for that switch, but I presume what happened was one of the COPs wasn't seating properly, as David mentions, until more driving and vibration moved it into position. I had great difficulty with cylinder 4 (I think that's no 4 - the rear one in the bank on the right hand side of the car). Very tricky getting the plug in and out and then pushing the COP back into place.

Malcolm