BMW Z3 Stalling & Jerking: Common Ignition Issues?

Hi there! I've got some experience with BMWs (some experience level). Had a similar issue with my 2004 BMW Z4 last year. The symptoms you're describing sound exactly like what I went through, that annoying stutter and jerking was driving me crazy! I took it to my regular workshop and turns out it was a loose connection in the ignition coil wiring harness. They found some worn-out cables and a damaged plug connection. The fix wasn't too complicated, they replaced the wiring and connections, cost me about 95 Euro. But before jumping to conclusions, would you mind sharing: Have you scanned for error codes? When did these symptoms first start? Does it happen more when the engine is cold or warm? Any recent work done on the car? By the way, if you're interested in BMWs, I also own a 3-Series and these models can have similar electrical quirks. Let me know these details and I might be able to help more specifically!

Thanks for the detailed reply! I've had my Z3 since 52726 KM and just got it serviced last month. I did scan for codes and got P0301 and P0303 (cylinder misfire). The symptoms started about two weeks ago, and yeah, it's definitely worse when the engine is cold, especially in the morning. The stuttering almost goes away once it warms up, but the jerking during acceleration is still there. No recent work apart from regular oil change and filter replacement during the service. Really appreciate the input about the wiring harness, I'll definitely get that checked. These old Beemers can be tricky with electrical issues, right? Did you have any recurring problems after fixing the wiring?

Hey again! I definitely feel your pain with those misfire codes, been there! After seeing your codes and symptoms, I'm even more convinced it's similar to what I dealt with on my Z4. Actually, after they fixed my wiring harness, the problem did come back after about a month. Turned out I had a bigger issue, it wasn't just the wiring but also a failing ignition coil. Those same codes you're getting (P0301 and P0303) were exactly what my car showed. Had to replace two ignition coils and the spark plugs while I was at it. For my Z4, the total fix ended up costing around 380 Euro (parts and labor). But honestly, it was worth every penny because the car runs like a dream now. No more cold start issues, no jerking, and that annoying check engine light finally stayed off. Just a heads up, if you're getting the ignition coils replaced, I'd strongly suggest doing all of them at once. These BMWs tend to have all coils fail within a short time of each other. Learned that the hard way when I tried replacing just one! Would you mind checking if your spark plugs are original? If they haven't been changed recently, might be worth doing those too while you're at it. Makes a world of difference!

Thanks so much for sharing your experience! That's super helpful to know about the recurring issues you had. I actually just checked my maintenance records, and my spark plugs were replaced about 40,000 KM ago, so they're probably due for a change anyway. You've convinced me to bite the bullet and replace all the ignition coils along with new plugs, better to do it all at once than keep having problems pop up. Going to book it in with my mechanic tomorrow and show him this thread. Really appreciate the detailed advice about the wiring harness check too. These old BMWs are such amazing cars when they're running right, but they sure keep us on our toes with maintenance! I'll probably end up spending more than I planned, but like you said, it'll be worth it to have it running properly again. I'll just have to eat instant noodles for a month to make up for it! Thanks again for all the help. Can't wait to get my Z3 back to its former glory. I've got a great weekend drive planned once it's fixed up!

2011 550i N63 engine cylinder 4 misfire/injection is cut out still after replacing old injector months ago. Is it due to air in combustion or carbon buildup clogged intake valve?

Start by checking the spark plug and ignition coil for cylinder 4, as these are common causes of misfires. If they are in good condition, inspect for any vacuum leaks or intake manifold issues that could affect air delivery. Carbon buildup can also be a factor, so consider a professional cleaning if other checks don't resolve the issue. Let me know how it goes or if you have further questions!