amelieshadow2
BMW Z3 Stalling & Rough Idle, Fuel System Troubleshooting
Shaking while idling
Fault stored
Car won't start
Stalling while idling
Check engine light on
Poor fuel economy
4 comment(s)
Thanks for your response! My Z3 has 64914 KM on it and had its last service about 3 months ago. Just got the error codes scanned yesterday, it's showing P0171 (System Too Lean) and P0303 (Cylinder 3 Misfire). The engine's actually the 3.0L straight-six. Your experience with the wiring connection is interesting, definitely something I hadn't considered. Did your mechanic mention any other potential causes they ruled out before finding the damaged cable? I'm trying to gather as much info as possible before taking it to the shop to avoid unnecessary repairs.
Hey again! I remembered something that might help you, when we had those error codes show up on my Z4, we also checked a few other things before finding that wiring issue. P0171 and P0303 are actually pretty common in these engines. With my car, the mechanic first suspected the fuel injector in cylinder 3 since the misfire code was specific to that cylinder. They tested my injectors and found that while the wiring was the main culprit, I also had a partially clogged injector in cylinder 3. The lean condition (P0171) was directly related to this, the damaged wiring was messing with the signal to the injector, causing irregular fuel delivery. Here's what I'd suggest based on my experience: Have them check both the injector and the wiring harness for that cylinder. In my case, replacing just the wiring wouldn't have completely solved the problem, I needed that injector cleaned too. The total job ended up being a bit more than just the wiring repair I mentioned before, but it was worth it to get everything sorted properly. Also, since you mentioned your recent service, did they change the fuel filter? If not, might be worth looking into that too. These BMWs can be pretty sensitive to fuel system issues. Let me know what you find out when you get it checked!
Thanks for all that detailed information! You know what, I think you might be onto something with the injector and wiring combination. Those error codes you mentioned match up exactly with what I'm seeing, and it makes a lot of sense that both issues could be happening together. The fuel filter wasn't actually changed during my last service, they just did the basics like oil change and general inspection. I'll definitely get that checked too when I take it in. Really appreciate you sharing your experience, especially about needing both the wiring fix and injector cleaning. Going to schedule an appointment with my mechanic tomorrow and make sure they look at all these potential issues. Honestly, it's such a relief to hear from someone who's dealt with similar problems. Was getting worried it might be something much more serious (and expensive!). I'll update the thread once I get it sorted out. Thanks again for all your help!
Hi there! (Some experience with BMWs) I had a really similar issue with my 2004 BMW Z4 last year. My symptoms matched yours pretty closely, rough idle, stalling, and that annoying check engine light. Initially thought it was the fuel pump too, but turned out to be a faulty wiring connection to the fuel injection system. Took it to my regular workshop, and they found a damaged cable that was causing inconsistent signals. The repair was pretty straightforward, they replaced the connection and did some testing. Cost me about 95 Euro and the car's been running smoothly since. Before we jump to conclusions though, what's your engine size, and have you scanned for error codes? Also, when was the last time you had a full service done? These details would help narrow down if your issue is similar to what I experienced. Feel free to share more info, and I'll try to help further!