Im posting with very little mechanical knowledge of cars:
In 2006 near winter time my car started to missfire. It caused a light do come on, on the dash board. Some times then it could missfire badly, the light would flash.
After a week or two of this, I took it to an Opel garage. They hooked it to their computer and said they need to replace the coil or "plug bar" as they called it.
Everythings grand for a few weeks, then it starts to missfire again, bring it back, and they load some treatment into the fuel and say drive around hatrd in 4th gear for a while. Week later - missfire, bring it back, they now say they have to take the head of the engine to clean gunk around valves, say it'll be at least €500 to take the head of alone, as you can imagine I said no. I got a bottle of fuel treatment that apparently frees up "sticky valves" and it didnt erally make a different. Eventually the problem resolved itself, the car stopped missfiring around mid February 2007.
Now January 2009 missfiring came back, in February I got sick of it and because I have no mechanical bacground, I was afraid I could be doing more damage so brought the car to another private mechanic. Read a missfire in cylindar 2+4. He assured me it was the coil gone again. Replaced that and replaced plugs. more €€€, few weeks later, car miss fired again. Brough it back and he read with computer and says it reported a missfire in cylindar 4, cleared fault and said to come back when it miss fires again. Now the car hasn't missfired again until now (September 2009)!!
I have begun to notice a pattern, like if you drive the car hard without the engine fully heated, like when I leave work, I have to enter a dual carrigeway/motorway.
Another funny thing I noticed is that if my car is missfiring when I accelerate, If i turn of the ignition for about 10-20 seconds, start it again and accelerate, the car wont missfire.
Does anyone have any idea how to solve this, I already have spent so much money on this with no results...