Coil Pack Failure
 

Hi. After having a coil pack fail on me recently, one of the terminals stopped emitting spark so I was running on only 3 cylinders, I had a new coil pack fitted (OEM) which, for a short time,seemed to fix the issue. i was disappointed, however, to have the original issue re appear, after just 4 journeys, and found, to my puzzlement, the new coil pack failed on exactly the same terminal as the original one, I am now only running on 3 cylinders (car garaged until I get to the bottom of this. is this coincidence or could there be more underlying problems that I'm not aware of that could cause this to happen again, in sich a short time. Thanks.

did you check the spark plug ?
high resistance could cause premature failure.

How so? I have changed the plugs over so the one in the non spark pot is now different. My mechanic can't get another coil pack until next Wednesday at best, all shut for Christmas so I can't see if this swap over has had any effect or not. I did check the gaps and adjusted slightly so they were correct. I wondered about the spark plug when it first went down but why should it suddenly break the coil pack if it has worked for some time, the plugs were changed in the last service, a number of Months ago.

Change the plug leads too. Can't hurt. One of mine went intermittent open circuit, caused a misfire. That wouldn't please the coilpack.

As the OP has said coil pack, Im assuming there is no lead,
You either want a fresh set of plugs, or a multi meter and check the resistance of the plug on the none spark pot and one that is known to be good, also check the insulation for signs of cracks on the plugs (You may have done this but its worth a mention)

Early failures of a new coil pack would indicate a high resistance on the secondary side, so that is spark plug really, as the plugs all thread into the same block, it rules out a poor ground on that side,
so the only thing between the coil pack and ground is the plug,

I assume the other coil pack was new ?
If so it should be under warranty, especially if it isnt very old, might save you a few quid.

Hi all, and especially JDM Stig. Yes, I suspected the plugs may have contributed to the issue, seemed rather strange
the same terminal was affected on the new coil pack. So I've got a new set of plugs and intend to fit at the same time
as the new coil pack. The HT leads are quite new (Fitted them myself) and have been OK up until this point so I sort of
ruled them out. The 2nd Coilpack was new (OEM) and it has a warranty but my mechanic is taking care of that issue with
his supplier. The annoying thing is the supplier sent a 2nd replacement which was in the same box, with the same part number
on the side but, when we got the part out of the box, it was the wrong part, had an extended stem with 3 pin connector for
the plug from the engine management system, mine has 4 with a short stem on the side of the Coilpack. So, now I have to
wait until,next Wednesday until we can try again. Thanks for all your help, I do appreciate it.