[harkes]

Got rough idle so changed the plugs and now also bought some BOSCH coils.

They are cheaper than the OEM Delphi but do they also last shorter?

[John in VA]

I've not been happy with Bosch parts for quite some time now, but haven't tried their F30 ignition coils. Delphi were original, I believe, and what I would choose. Bremi parts have been better than Bosch, but, again, don't have F30 coil experience with them.

[F32Fleet]

Originally Posted by harkes

Got rough idle so changed the plugs and now also bought some BOSCH coils.

They are cheaper than the OEM Delphi but do they also last shorter?

BMW ignition coils typically have a 100k mile change interval so I doubt many people have experience to share.

[CarlosC]

I recently swapped all of my ignition coils and used the Delphi (non-BMW branded) coils. Saved quite a bit versus buying the BMW branded versions and they were 100% identical to the original coils that were in my car. Even the Delphi logo stamp is in the same place on both.

[Rebound]

Originally Posted by F32Fleet

BMW ignition coils typically have a 100k mile change interval so I doubt many people have experience to share.

I never saw a 100K interval in any of the manuals. Is that official, or is it what you’ve learned from experience? Seems to me that they last until age deteriorates the insulating material. But I ask to learn, not to doubt you.

[Billfitz]

I'm not sure about a recommended interval for the coils. Most people change them when they change the plugs, since they have to be removed to change the plugs anyway.

[harkes]

Originally Posted by Billfitz

I'm not sure about a recommended interval for the coils. Most people change them when they change the plugs, since they have to be removed to change the plugs anyway.

WHAT?!?

Sorry, but that would be idiocy. Coils should easily last 50000 miles.

[Billfitz]

So should plugs. Most manufacturers have an 80,000 mile plug change interval. Toyota says 120,000 miles, and they're not known for having reliability problems. BMWs interval seems way too conservative.

[328iX]

Sorry but who the hell replaces coils on a plug change interval? I highly doubt it's on a 100k interval, that sounds like the spark plugs, and even then Iridium plugs usually easily last 150k-200k

[Rebound]

Originally Posted by harkes

WHAT?!?

Sorry, but that would be idiocy. Coils should easily last 50000 miles.

BMW's Spark plug interval on the N55 is 60,000 miles, and as another poster mentioned, Toyota's interval is 120,000 miles. The new iridium technology has extended plug life dramatically.

I only had an ignition coil fail once, on a friend's VW New Beetle. I'd changed the spark plugs, and I must have damaged one in the process. The plastic and rubber insulation gets pretty fragile over time. Very easy to diagnose — the ODB 2 reported a misfire in the affected cylinder. Swapped coil with another cylinder, and misfire error followed the coil.

[harkes]

Originally Posted by Rebound

BMW's Spark plug interval on the N55 is 60,000 miles, and as another poster mentioned, Toyota's interval is 120,000 miles. The new iridium technology has extended plug life dramatically.

I only had an ignition coil fail once, on a friend's CW Beetle. I'd changed the spark plugs, and I must have damaged one in the process. The plastic and rubber insulation gets pretty fragile over time. Very easy to diagnose — the EDB reported a misfire in the affected cylinder. Swapped coil with another cylinder, and misfire error followed the coil.

OK, I didn't know that. My car is big turbo'ed so I have tried different plugs and switched around. I expect to change plugs @ 30000 miles and coils at double that. If they last longer = bonus.

[328iX]

Originally Posted by harkes

OK, I didn't know that. My car is big turbo'ed so I have tried different plugs and switched around. I expect to change plugs @ 30000 miles and coils at double that. If they last longer = bonus.

coils aren't on a maintenance schedule, they should be good for the life of the car, only replaced if they fail.

[harkes]

Originally Posted by 328dX

coils aren't on a maintenance schedule, they should be good for the life of the car, only replaced if they fail.

At 60000 miles I had a problem. At every startup cyl 2 would not fire. Un/re-plugging the coil would fix the problem. Probably just the coil shaking loose but I decided to replace all of them as they are relatively cheap. Hope you are right and that I can do the next 100k problem free