BMW Z3 ABS & Traction Woes: Jerky Acceleration Mystery

Hey there! I had the exact same symptoms on my 2004 BMW Z4 3.0i last summer. The jerking during acceleration combined with ABS/ASC lights was definitely an ASC relay failure in my case. The relay module was completely fried when the mechanic checked it. Had it handled at my usual garage, they had to replace the entire ASC control module since just swapping the relay wasn't possible on my model. It wasn't a quick fix, took them about 4-5 hours total with diagnostics and everything. Pretty serious issue since it affects your car's stability control and braking systems, definitely not something you want to ignore. From my experience, find someone who specializes in BMW electronics. Regular shops often misdiagnose these symptoms as transmission issues, which could lead to unnecessary repairs. The ASC/ABS problems need proper diagnostic equipment to pinpoint the exact fault. Hope this helps!

Thanks for sharing your experience! That ASC control module issue sounds exactly like what I'm dealing with. Just wondering, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since the fix, or have you noticed any other quirks pop up? Always good to know what I might need to watch out for with these systems.

Hey again! Just wanted to follow up, great news! I actually got this sorted last week and yes, it was definitely the ASC relay like I suspected. My total bill came to 90 € for the repair, which was way less than I expected after my mechanic originally quoted me for a full module replacement. Everything's running perfectly smooth now, no more jerking during acceleration, and those annoying warning lights have completely disappeared. The ASC system's working like a charm, just like when the car was new. Talk about a relief! It's funny looking back at how worried I was about needing a complete module replacement like in my original diagnosis. Turns out it was just a faulty relay. Been driving daily since the fix and haven't noticed any other issues cropping up. The car's handling beautifully in all conditions. Quick word of advice, if anyone else runs into this, definitely get a second opinion from a BMW specialist. Not every shop has the right diagnostic tools to pinpoint these electrical gremlins accurately. Sometimes the simpler (and cheaper!) fix is the right one. Let me know if you need any other details!

Thanks everyone for your help! Just wanted to update you all on what happened. I finally took my Z3 to a new mechanic who specializes in BMW electronics. Got pretty lucky, turned out it wasn't as bad as I feared. The whole ordeal was actually quite interesting. When I brought it in, the mechanic hooked it up to their diagnostic system and found the issue right away. Like many of you suggested, it was indeed related to the ASC system. They spotted a failing relay that was causing all those symptoms, the jerking during acceleration and those annoying warning lights. The repair took about two hours, and I was honestly shocked when I got the bill, it was much lower than I expected. The car's running perfectly now, no more jerking, no warning lights, and the ABS and ASC are working exactly as they should. Really glad I asked here first and avoided going back to my old mechanic. Sometimes you just need to find the right mechanic for the job. Thanks again for all the helpful advice!