BMW Z4 Cold Start Issues: Bad Injector Symptoms?

Hi there! I have some experience working on cars and had a similar issue with my 2018 BMW M4 last winter. The symptoms you're describing sound exactly like what I went through. My car had rough starts, especially on cold mornings, and was burning through fuel like crazy. After struggling with it for a couple weeks, I took it to my regular workshop. They diagnosed it as a faulty fuel injector and had to replace it. The whole thing, including parts and labor, set me back about 515 Euro. Since then, the car's been running perfectly smooth. Just a heads up, before jumping to conclusions, it would help if you could share: How many miles/km are on your Z4? Are you getting any check engine lights? Does it run better once the engine warms up? This way, I can give you more specific advice based on my experience with BMWs.

Thanks for the detailed response! I've got 48215 KM on the clock, and yes, it definitely runs better once warmed up. No check engine lights so far. Had my last service about two months ago where everything looked fine, but this issue started popping up recently. Your experience sounds very similar to what I'm dealing with. Did you notice any specific sounds or vibrations during those cold starts? And did your fuel consumption go back to normal after the injector replacement? Just trying to compare symptoms before I book a workshop appointment.

Hey again! Yeah, my M4 was showing almost identical symptoms at around 45000 KM, so we're in the same ballpark mileage-wise. To answer your questions, yes, I definitely noticed some unusual vibrations during cold starts. It was like a slight shuddering that lasted about 10-15 seconds, and sometimes there was this faint ticking noise. Super annoying, especially on those chilly mornings! And about the fuel consumption, it improved dramatically after the injector replacement. I was burning through about 15-20% more fuel before the fix, but it went right back to normal afterward. Actually, I started tracking my fuel usage with an app, and the difference was pretty clear, dropped right back to what it should be within the first tank after the repair. Since your symptoms are so similar and you're also driving a recent BMW, I'd really recommend getting it checked soon. These issues typically don't fix themselves, and waiting too long might cause more problems. My mechanic mentioned that modern BMWs are pretty sensitive to injector issues, so it's worth getting it sorted while it's still just affecting the cold starts. Let me know what you find out when you get it checked. I'm curious if it turns out to be the same issue!

Thanks so much for the follow-up! That's actually really helpful to hear about the shuddering and ticking noise, I'm getting exactly the same thing! And knowing your fuel consumption went back to normal after the fix gives me hope. I've actually just booked my Z4 in for next week at my local BMW specialist. You're right about not waiting too long, I've been putting it off for a few weeks now, but after hearing about your experience, I definitely want to get it sorted before it potentially causes any other issues. The similarity in mileage when the problem started is pretty striking too. I'll definitely let you know what they find once they've had a look at it. Really appreciate you taking the time to share your experience, it's made me feel a lot more confident about what might be going on. Fingers crossed it's just the injector and nothing more serious! Thanks again for all the info. I'll update the thread once I know more!