Hi Scotty. Have a 2009 BMW 328i. It has 147k miles and has an automatic transmission. The problem that is occurring happens when the car idles. If it sits idling for about 10 minutes it makes a loud thud noise and goes into half power or “limp” mode and the rpms kinda go nuts like it’s about to die and it makes an ear piercing screeching noise from under the hood. If I turn it off for about 30 seconds and restart it everything runs normally like it never happened and the limp mode goes away too. So my question is what is causing it to do all this and what is most likely making the loud screeching noise occur?
thank you!
You are gonna have to get a mechanic who knows BMW’s and has a scanner capable of talking to all of BMW modules. There should be codes telling you whats happening. If not they can examine the live data and see what’s happening.
I didn't have the exact problem, but something similar on my old BMW X5 2007. Maybe it will point you to the right direction.
I had the screeching sound. It happened here and there and would never go away on its own. But once I turned the car off, and then back on, it did go away.
I suspect it was the PCV valve attached to the valve cover. Because when I changed the valve cover and valve cover gasket, the problem went away.
