BMW Z4 Idling Issues & Power Loss, Fuel System Problems?

Hey there! I had pretty similar issues with my 2017 BMW M2 last year. I have some experience working on cars, but this was beyond my DIY skills. My symptoms were almost identical, rough idle, power loss, and that annoying CEL. Took it to my trusted workshop and turns out the high pressure fuel pump was failing. They replaced it, and the car's been running like new since then. Set me back about 1510 Euro, including parts and labor. Not cheap, but better than risking further damage. Which engine variant does your Z4 have? Also, have you scanned for error codes? This info would help confirm if we're dealing with the same issue. These symptoms can sometimes be tricky to diagnose without proper testing. BMW fuel systems can be quite sensitive. My mechanic mentioned it's not uncommon in several BMW models, including the Z4 and M2.

Thanks for sharing your experience! I've got the B58 engine in my Z4 with 85219 KM on the clock. I haven't scanned for codes yet, but your fuel pump theory makes a lot of sense. The symptoms are eerily similar to what you described. I might have to bite the bullet and visit a workshop since this definitely sounds beyond my amateur mechanical skills. Really hoping it's just the fuel pump and nothing more serious. Did you notice any warning signs before it completely started acting up?

Hey again! Glad I could help. Yeah, with my M2, I actually did notice some warning signs before it got really bad. At first, it was just occasional hesitation when accelerating from a stop, you know, that slight lag that makes you think "hmm, that's not normal." I ignored it for about two weeks (big mistake!), and then the idle problems started getting worse. One thing I forgot to mention in my previous reply, before the complete failure, my car would sometimes have trouble starting in the mornings. It would crank a bit longer than usual. Looking back, that was definitely a red flag I should've paid attention to. With the B58 engine and those kilometers, it's right in the sweet spot where these issues tend to pop up. My M2 had around 78000 KM when the pump failed. If it helps, after the new pump was installed, they also recommended changing the fuel filter as preventive maintenance. Ended up doing that too, and honestly, the car felt even better. Just a heads up, when you take it in, make sure they check the fuel pressure sensor too. Mine was fine, but the mechanic said they sometimes go bad along with the pump. Better to check everything while they're in there, you know?

Thanks so much for all the detailed info! Actually, now that you mention it, I have been experiencing those longer start times in the morning for the past few weeks. Just brushed it off thinking it was because of the cold weather. And yeah, that hesitation from a stop, I've definitely noticed that too but didn't connect the dots until now. Really kicking myself for not looking into it sooner. I'll definitely get it checked out this week and make sure they look at both the pump and the pressure sensor. Thanks for the tip about the fuel filter too, might as well do that while they're at it. Always better to be thorough, right? Seems like catching it now might save me from bigger headaches down the road. I'll update the thread once I get it sorted out. Really appreciate all your help on this!