BMW M3 VANOS Nightmare: Help with Power Loss Issues

Hey there! I had a similar problem with my 2006 BMW M5 last year, and I've got some experience working on cars (I'd say low to moderate experience, mostly basic maintenance and simple repairs). The symptoms you're describing sound exactly like what I faced. After the check engine light came on and I noticed the rough idle, I took it to my trusted workshop. They diagnosed a faulty camshaft solenoid valve on the intake side. The repair set me back about 250 Euro, but it completely solved the issues, no more rough idle, power was restored, and fuel consumption went back to normal. Before you proceed, could you share: Have you scanned for error codes? When was your last oil change? Does the noise get worse when the engine is cold? These details would help understand if you're dealing with the same issue I had. The M3 and M5 share similar VANOS systems, so I might be able to provide more specific insights based on your answers.

Thanks for the detailed response! Yeah, I've got the P0012 code after scanning. My last service was just 3,000 KM ago where they did a full oil change with the recommended 10W-60. The noise is definitely more noticeable during cold starts, and it does seem to get a bit better once the engine warms up. Really helpful to hear about your M5 experience, sounds spot on with what I'm dealing with. The repair cost seems reasonable too, way better than what I was fearing! I'm just a bit worried cause at 123591 KM, I'm wondering if there might be other related issues to look out for while they're in there. Did your mechanic mention anything about checking other components while doing the solenoid replacement?

Hey again! Yeah, those details definitely confirm what I suspected, sounds exactly like what I dealt with on my M5. That P0012 code is pretty much a smoking gun for the intake VANOS solenoid. When I had mine fixed, my mechanic actually recommended checking the VANOS seals while they were in there. I'm glad they did because they found the seals were pretty worn too. Makes sense given your mileage, my M5 was around 130000 KM when I had the work done. The seals aren't too expensive, but since they're already taking things apart for the solenoid, it's smart to replace them at the same time. Saved me from potentially having to do another tear-down later. One thing I learned from my experience, make sure they clean out the VANOS unit properly when they're in there. Mine had some gunk built up, and cleaning it made a noticeable difference in how smooth the engine runs. Also, after the repair, I switched to more frequent oil changes (every 7,000 KM instead of 10,000), and it seems to help keep things running smoother. The total job with both solenoid and seals ended up costing me around 500 Euro, but honestly, it was worth every cent. The car runs like new now, no more weird noises, power's back, and fuel economy is spot on. Let me know how it goes if you decide to get it fixed!

Thanks so much for all this info! That's really reassuring about getting both the solenoid and seals done together, definitely makes sense to tackle it all at once rather than risking another repair job down the line. I'll make sure to ask my mechanic about doing both, plus that thorough VANOS cleaning you mentioned. 500 Euro for the whole job sounds like a solid deal, especially if it sorts everything out completely. I've already called my regular shop and booked it in for next week. They said they're familiar with these VANOS issues on M3s, so hopefully they'll be able to handle everything you've suggested. I'll definitely take your advice about more frequent oil changes too, seems like a smart preventive measure. Really appreciate you taking the time to share your experience in such detail. It's made me feel a lot more confident about getting this sorted. I'll update the thread once it's all done in case anyone else runs into similar issues in the future!