BMW Z4 Jerking & Poor Performance: Throttle Issues?

Hey there! I had a similar issue with my 2008 BMW M3 last year (I have some experience working on cars, but mainly basic maintenance). The symptoms you're describing sound exactly like what I went through, jerky acceleration, poor throttle response, and higher fuel consumption. In my case, it turned out to be a defective accelerator pedal module. Had it diagnosed at my regular workshop, and they found that the sensor in the pedal module was failing. The fix wasn't too complex, they replaced the module, and it cost me around 205 Euro. Since then, the car's been running smooth as butter. Before jumping to conclusions about the throttle valve though, what's the mileage on your Z4? And have you noticed any warning lights on the dashboard? This info would help determine if you're dealing with the same issue I had. Let me know these details, and I might be able to share more specific insights about what to look out for.

Hi again! My Z4 has 111008 KM on the clock and had its last service about 4 months ago. Actually, haven't seen any warning lights on the dashboard, which makes it even more puzzling. It just progressively got worse over the last few weeks. The sluggish response is most noticeable when trying to accelerate from a stop. Thanks for sharing about the accelerator pedal module, that's definitely something I hadn't considered. The symptoms do sound very similar. Did you notice if your car also had trouble starting before you got it fixed? That's one extra issue I'm dealing with that makes me wonder if it might be something else. Really appreciate your help on this!

Hey again! Thanks for those details about your Z4. You know what's interesting? The starting issue you mentioned, I actually did experience that too, but I didn't connect it to the accelerator pedal module problem initially. It wasn't as noticeable as the other symptoms, but looking back, my M3 did have some hesitation when starting, especially on colder mornings. The mileage on your car is pretty similar to what mine had when the problem showed up (I was at around 108000 KM). And just like your case, I didn't have any warning lights either, which was super confusing at first. It's pretty typical for these BMWs to have these kinds of quirks without throwing any codes. After getting the pedal module replaced, not only did the jerking and fuel consumption issues clear up, but that slight starting hesitation disappeared too. It was like getting a new car! Here's something I learned though, my mechanic mentioned that sometimes these symptoms can also be caused by a dirty throttle body or faulty MAF sensor. But given how similar your symptoms are to what I experienced, including that starting issue, I'd put my money on the accelerator pedal module. Might be worth getting that checked first before looking at the throttle valve. Let me know what you find out, really curious to hear if it's the same issue!

Thanks so much for the detailed follow-up! That's really helpful, especially knowing that you experienced the starting issues too. I was getting worried it might be multiple problems, but hearing your experience makes me feel a bit better about it. I've actually just called my mechanic and booked the car in for next week. I mentioned the accelerator pedal module possibility, and he agreed it's worth checking first before diving into the throttle valve inspection. He said he's seen this issue a few times with BMWs of our generation. The price you mentioned seems reasonable too, definitely better than what I was expecting if it had been the throttle valve! I'll update the thread once I get it diagnosed and fixed. Really appreciate you taking the time to share your experience. It's made me feel much more confident about getting this sorted out. Thanks again for all your help!