[Suvorovo]

2006 330xi 6 Speed N52. Recently had a ton of work done to my car at a mechanic. The mechanic drove the car, no codes or issues with running.
I drove for about 8 miles on my way home and Cylinder 3 began to missfire. At first it popped up during low fuel condition (a separate code).
Filled up tank, reset codes, and still continues to missfire/running on 5 cylinders. What could it be if it ran fine for a little bit? I'm taking the car back to the mechanic given the amount of work that was done, I don't want to disturb anything that could have been broken during the job.

1. Aluminum head bolt replacement. (Cam Adjuster units removed)
2. Valve Cover/All associated bolts and gaskets
3. VDO Eccentric shaft sensor
4. Bosch (Slovenia) coils and Bosch plugs
5. PCV

This that come to mind, but worried it could be something much graver:
- Bad coil
- Bad plug
- Broken injector (fuel line was disconnected during the repair)
- Mechanic connected the interference supression band on the ignition coil harness to the secondary air system cover bolt. Was originally connected to the ignition coil harness. Don't really understand how the interference band works, could just be this.

[e91Owner]

Could be as simple as the coil not being seated. It would just be a WAG by anyone based on the information you’ve given. They will likely see if it’s the problem above, if not they would swap the coils to see if follows the current coil in cylinder 5 to rule out a bad coil.

Bosch plugs and coils aren’t won’t most people would use today, but the brand (Delphi vs Bosch coils, NGK vs Bosch plugs) likely isn’t the problem.

While the interference suppression band should be connected properly (neither configuration that you described sounds correct to me), it is essentially just another ground, so as long as there is an electrical path from block to body, it shouldn’t matter.

[Suvorovo]

Originally Posted by e91Owner

Could be as simple as the coil not being seated. It would just be a WAG by anyone based on the information you’ve given. They will likely see if it’s the problem above, if not they would swap the coils to see if follows the current coil in cylinder 5 to rule out a bad coil.

Bosch plugs and coils aren’t won’t most people would use today, but the brand (Delphi vs Bosch coils, NGK vs Bosch plugs) likely isn’t the problem.

While the interference suppression band should be connected properly (neither configuration that you described sounds correct to me), it is essentially just another ground, so as long as there is an electrical path from block to body, it shouldn’t matter.

I have old style connectors on my harness. I couldn't find Eldor coils with those connectors + buying those on ebay isnt ideal. Delphi is manufactured in China while Bosch was Slovenia. Took the bosch route...

[e91Owner]

Originally Posted by Suvorovo

I have old style connectors on my harness. I couldn't find Eldor coils with those connectors. Delphi is manufactured in China while Bosch was Slovenia. Took the bosch route...

It’s not the place of manufacture that matters, but the coil itself. It’s a better coil, but if you’re stock, you’ll probably never notice the difference as long as it’s working. You can’t tell what engine you’re talking about on the app, so I was assuming N52.

[Suvorovo]

Originally Posted by e91Owner

It’s not the place of manufacture that matters, but the coil itself. It’s a better coil, but if you’re stock, you’ll probably never notice the difference as long as it’s working. You can’t tell what engine you’re talking about on the app, so I was assuming N52.

Can I drive 10 miles with the missfire? I don't want to touch anything given the mechanic did the work incase it's a bigger issue.

[Suvorovo]

Originally Posted by Suvorovo

Can I drive 10 miles with the missfire? I don't want to touch anything given the mechanic did the work incase it's a bigger issue.

Mechanic gave me the ok to troubleshoot the coils myself. Is it ok to temporarily use my old original BMW coils to see if the missfire continues on that cylinder? I've read that there's a chance the connection may be frying coils and I would prefer not to swap coils between cylinders if they're working fine.

I understand mixing old and new coils is bad.