BMW Z3 Stalling & Air Pump Issues, Common Fixes Needed

Having some experience working on BMWs, I dealt with a similar issue on my 1998 BMW Z4. The symptoms were practically identical to what you're describing. After struggling with it for a while, I took it to my trusted mechanic who diagnosed a faulty hose connection between the secondary air pump and valve. Total repair cost was 175 Euro, pretty straightforward fix once they identified the issue. The repair really improved things, no more stalling or jerking, and the check engine light hasn't come back on since. The air pump now runs normally too. To help you better, could you share: Any specific error codes you're getting? When did these symptoms first start? Does it happen more when the engine is cold or warm?

Thanks for sharing your experience! My Z3 has 144691 KM on the clock and just had its service last month. I'm getting error code P0410, and the problems started about two weeks ago. Interestingly, it's most noticeable when the engine is cold, especially during morning starts. After it warms up, the jerking isn't as bad, but the check engine light stays on. Your hose connection issue sounds similar to what I might be dealing with. The repair cost seems reasonable too. I'll have my mechanic take a look at those connections first before replacing any major parts. Thanks for the tip!

Hey there again! Glad my previous response about the hose connection was helpful. After reading about your specific situation with the P0410 code and cold start issues, I'm even more convinced we had the same problem. On my Z4, I also noticed it was way worse during cold starts. What really caught my attention in your reply is that the problems started soon after a service. You know what's funny? The same thing happened with mine, issues popped up about two weeks after routine maintenance. Turned out one of the hose clamps wasn't properly tightened during the service. The P0410 code is definitely related to the secondary air injection system, which matches perfectly with those symptoms. Since you mentioned your car has 144691 KM, it's around the same mileage where these issues typically show up in these models. Quick tip from my experience, have your mechanic check the electrical connections to the air pump too while they're at it. Sometimes moisture can get in there and cause similar symptoms. It's worth looking at since they'll already be poking around that area. Would be great if you could update us after your mechanic takes a look. I'm curious to know if it's the same issue I had with mine!

Thanks so much for all this detailed info! It's really reassuring to hear that your Z4 had such a similar issue, especially with the timing after the service. I've actually just booked my car in for tomorrow morning, and I'll definitely ask them to check both the hose connections and those electrical connections you mentioned. Your point about the moisture getting into the electrical connections is particularly interesting, we've had quite a bit of wet weather lately, so that could definitely be contributing to the problem. And knowing that these issues are common at this mileage helps me feel better about the whole situation. I really appreciate you taking the time to share your experience and tips. I'll make sure to come back and update everyone once I get the diagnosis and repair done. Fingers crossed it's just a loose hose clamp like in your case, that would be the best-case scenario! Thanks again for your help!