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Discussion Starter #1
I have been having some misfires and rough running for a few weeks now and finally got it resolved. :flag:

Short Version

I got code 34 (cyl 5 ignition coil); sat on it for 3 weeks; replaced the coil; happy camper :)

Long Version

I started feeling some hesitation when taking off in first at low rpms a few weeks ago. I was about to have my clutch replaced, so I figured it was related to the clutch, so I decided to wait it out and see if it went away. Some of you may remember that we had trouble starting my car after the clutch replacement which was eventually attributed to flywheel alignment, but in the meantime, there were a million different possible suspects, so my mind was all over the place. After that was resolved, I got the car back and there was still some hesitation at low rpms, so I got out the Peake reader. I got code 34 for cyl 5 ignition coil and d1 for cyl 5 warm-up misfire. I generally ignore the warm-up misfire codes and did not initially catch that both codes were for cylinder 5. ouich So I thought I would clear the codes and see what comes back.

I continued to get warm-up misfire codes on multiple cylinders (including cyl 5), but did not get the ignition coil code again, so I thought it was a fluke. Wrong. The hesitation continued to get worse and the car was running rough and vibrating. Over the course of the next week or so, I replaced the upper oil separator hoses, cleaned the oil separators, and cleaned the MAFS, but did not see any improvement with any of those things. (At least I got some good preventative maintenance done.)

So I started reading the board looking for ideas about hesitation at low rpms and of course came up with a million possibilities. So now my mind is spinning with all this information and I start to panic. I can't afford to start throwing parts at the car hoping to fix the problem and I don't want to go to the dealer.

Well, yesterday the car was almost undriveable (vibration at all rpms). I knew I needed to do something, so I asked a friend if our local indy had a GT1 thinking that maybe it would reveal the cause of my problems. He suggested that maybe I didn't need the GT1 - maybe the Peake codes are revealing the problem. He was right (thanks Richard).

I came across this video this morning and was encouraged by how simple testing and changing an ignition coil could be, so I headed home to try it out:

YouTube - BMW E46 M3 Ignition Coil Replacement and Cylinder Misfire

The dealer wanted $80 for a coil (after 10% CCA discount), but the international parts store had it for $60. I picked it up, swapped it in and as soon as I started it up, I knew it felt better. What a relief.

I can't find the thread now, but I remember someone saying that there are a number of sensors and factors that need to be in harmony for the beast to run just right. On one hand, that is sort of discouraging, but on the other hand, it can be seen as goal to aim for. Yesterday I was discouraged, but today was a victory! :goldcup:

Questions

Is it ok to only replace a single coil or should I do the others as well? How long are they expected to last?

Do you think the bad coil would have caused any damage to the spark plug? Maybe it's time to replace my plugs anyway. They have 3 yrs and about 35k miles on them. How long do plugs last?
 

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Registered
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Questions

Is it ok to only replace a single coil or should I do the others as well? How long are they expected to last?

Do you think the bad coil would have caused any damage to the spark plug? Maybe it's time to replace my plugs anyway. They have 3 yrs and about 35k miles on them. How long do plugs last?
I would replace all the coils while you are at it, I had 1 coil gone bad and a couple thousand miles later, some other ones went bad as well. So from my experience, just replace all of them.

I would replace the plugs too while you are at it, they are cheaper than the coils, it's about time after 35k miles too.
 
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