128i Engine Miss

[MontegoCoupe]

Hope this helps folks. My 2012 128i developed an engine miss last week. Seemed like an ignition miss and would only happen when accelerating. Usually when merging with traffic or passing, rarely from a start. Idled fine. I replaced the spark plugs which looked worn and had about .060" gap. She has 68K miles. I replaced them with the only plugs available from any of the parts stores in town, Denso Iridium TT IKH20TT. Resolved the problem and she runs great again. I would have preferred NGK or Bosch, but she's happy. Pretty easy to change after watching a couple YouTube video.

Hope this helps anyone else that experiences a miss in their 128i.

MontegoCoupe

[bmw1racer]

Hmm, since it's a 2012, I would've thought you'd take it to the dealership, since it's probably still under warranty...

[Silenus]

Originally Posted by bmw1racer

Hmm, since it's a 2012, I would've thought you'd take it to the dealership, since it's probably still under warranty...

Not at 68,000 miles. Unless it's a CPO.

Anyways, misfires on the N51 are caused by a coil, 8 times out of 10.

[MontegoCoupe]

Originally Posted by Silenus

Not at 68,000 miles. Unless it's a CPO.

Anyways, misfires on the N51 are caused by a coil, 8 times out of 10.

Not under warranty, dealer is 45 minutes away. Took me about an hour to replace. A coil was my first thought based on the reports of others. Figured I'd start with plugs. I suppose it's still possible to have a weak coil considering the gap is now smaller. Time will tell, but for now plugs fixed her.

MontegoCoupe

[mrh1965]

Originally Posted by Silenus

Anyways, misfires on the N51 are caused by a coil, 8 times out of 10.

That's what I was thinking. I had a misfire develop around Thanksgiving, at times it was very bad but then it settled down to just a little stumbling under light acceleration. One coil later and I was back in business. My check engine light was on intermittently, don't know about you. Best of luck.

[m_thompson]

My N51 has done this twice in the last month. After a few seconds it goes back to normal. I will pull the codes and talk to the dealer about getting it fixed under the long term California emissions warranty.

[bmw1racer]

Originally Posted by Silenus

Not at 68,000 miles. Unless it's a CPO.

Yikes, I missed that bit of info... Sorry.

[bayerwhat]

I started noticing the same problem as OP on my 2011 128i, gradually getting worse...engine stuttering and shaking when accelerating with a cold engine (less that 10 minutes warmup). Back off the gas and it would go away, but if I continued giving it gas the CEL would come on and the problem would persist until I powered the car off/on again (awkward, but not a problem with the 6-speed). Otherwise, normal running.

Anyway, 70k miles, out of warranty, so I went ahead and changed the spark plugs since they were overdue. Not a hard job aside from getting to the coils. And I needed over 6" of extension for my ratchet at one point. I also ended up changing out the cabin filter on the way. Bosch double-platinums, in stock at AutoZone. Originals were NGK and looked pretty well-worn:



Problem solved...full acceleration restored. Hope this helps others.

[mr.fabulous]

Originally Posted by bayerwhat

Bosch double-platinums, in stock at AutoZone. Originals were NGK and looked pretty well-worn:

Those NGKs cannot be factory....

[bmw1racer]

Originally Posted by mr.fabulous

Those NGKs cannot be factory....

They are marked "BMW."

[bayerwhat]

Originally Posted by mr.fabulous

Those NGKs cannot be factory....

It's possible, I bought the car from a non-BMW dealer with 29k miles, but I tend to doubt they replaced them.