BMW Z3 EGR Issues: Power Loss and Rough Running Help

Hi there! I have some experience working on cars, and I actually faced a very similar issue with my 2004 BMW Z4 last year. The symptoms you're describing are exactly what I experienced, the poor performance, smoke, and that annoying hissing sound. Turns out it was indeed the EGR valve. Took it to my trusted workshop, and they confirmed it was completely clogged up. The whole thing, including diagnostics and replacement, cost me around 355 Euro. The difference in performance after fixing it was like night and day, no more jerking or smoke, and my fuel consumption went back to normal. Mind sharing what error codes you're getting? Also, have you noticed if these symptoms are worse when the engine is cold or warm? This could help confirm if we're dealing with the same issue here. By the way, I've seen similar problems with other BMWs of that era, including the 3 series from those years. Usually, once the EGR is replaced, it's problem solved.

Thanks for sharing your experience! My Z3 just hit 100737 KM and I'm getting similar symptoms. The error codes are throwing P0401 and P0403, mostly pointing to the EGR system. Interestingly, the symptoms are definitely worse when the engine is cold, especially during morning starts. After about 10-15 minutes of driving, it seems to smooth out a bit, but the jerking and smoke are still there. Good to hear that replacing the EGR sorted out your issues. That price seems reasonable, considering what I've been quoted. Did you have any other related components that needed attention while they were in there? I'm thinking of getting the EGR cooler checked out too while they're at it.

Hey again! Yep, those error codes definitely confirm what I suspected. On my Z4, I also had P0401 and P0403, and the cold start issues were identical. It's actually quite common with these BMW engines once they hit around 100,000 KM. Smart thinking about the EGR cooler! When they were working on mine, they actually found that the EGR cooler had some scaling buildup too. I decided to get it cleaned while everything was apart, added about 120 Euro to the bill, but it was worth it to prevent future issues. The mechanic showed me the gunk that had built up in there, and honestly, I'm surprised it was working at all. Since we've got such similar cases, I'd definitely recommend getting both done. The labor cost won't increase much since they're already in there. After fixing both components, my cold starts became super smooth, and I haven't had a single issue in the past year. Just make sure they use genuine BMW parts, I tried saving money once with an aftermarket EGR valve on my old car, and it didn't last six months. Let me know how it goes after you get it fixed. Would be interested to hear if you get the same improvements I did!

Thanks so much for all the detailed info! Just got back from the mechanic today, and you were absolutely right about everything. They found both the EGR valve and cooler were pretty gunked up. Ended up replacing the valve and cleaning the cooler, just like you suggested. The total came to 475 Euro, a bit more than yours but they had to do some extra cleaning on the intake manifold too. The difference is incredible! First cold start this morning was butter smooth, no jerking, no smoke, nothing. Took it for a proper drive and the engine feels so much more responsive now. Definitely glad I got the cooler sorted while they were in there. You saved me from potentially having to go back for that later. Really appreciate your help with this. It's such a relief to have my Z3 running properly again. I'll definitely keep an eye on the EGR system from now on and might get it checked during regular services to prevent another buildup. Thanks again for pointing me in the right direction!