[janpa7]

Originally Posted by Mustafa.e92

You can get a cheap walnut blast kit and adapter for under $250. The valves get squeaky clean with minimal effort within minutes.
Make sure the injectore bore is clean and inspect it visually. The Teflon seals should be expanded, slid onto injector, compressed again, than installed right away.
Teflon tape and stuff are bandaid fixes. Oval happens due to improper removal of injectors usually from people wiggling them. Some jackasses forget the decoupler that can also cause that. If everything with the new injector install checks out. I’d look into the injectore bore. If you have access to a leak down tester that will also help you determine if that is the cause.
Proper fix is the pfi injector bore repair kit. You can search about it on Facebook forums much more active

Hello,

I have an update. I solved the issue. My DME was defective (and it was a MSD81 !!!)... Someone sold me a defective MSD81 DME on ebay... and after 1 year of troubleshooting, spending thousands on different parts, it was all just because a dishonest person who sold me a defective DME...

Now I have no more misfire... my car is buttery smooth! however, my car developed a subtle intermittent knock. It sometimes disappears, sometimes appears. I suspect rod knock. I am scheduled to do an engine rebuild in October 2024 anyways. I am so tired of chasing issues endlessly and not being able to drive my car...

[janpa7]

Originally Posted by Biggsie

Update on this? Did you ever do the o2 sensors?

Yes, I did all O2 sensors, but that wasn't my issue at all. It didn't improve anything. my MSD81 DME was just bad, I bought an original DME from factory and now my car runs incredibly smooth without any misfires!

I didn't have 30BA and 30BB error codes, as it is usually the case when mosfets in DME go bad, so I had no clue my DME could be bad.

I recommend everyone who still have misfire after changing plugs, coils and injectors to check their DME and buy the latest version, and I'm not talking about MSD81 versus MSD80, but the latest revision of the MSD81 (yes, the DME in N54s had more revisions than the injectors, as an official BMW mechanic told me, and I suspect the DME could be the cause when people are chasing misfire issues for months/years). My intake valves are pretty dirty, but that didn't cause misfire in my case. And my injector bores were not ovaled or anything.

I don't recommend buying DMEs on ebay as you will likely not get the latest revision and someone dishonest may sell you a defective one. Just buy one from BMW for peace of mind. It will be expensive, but at least you will save yourself a lot of trouble.