[scottjeffrey]

Hi, I have owned this 2009 328i since new. It has 170,000 miles currently.
I have maintained it well. In November I encountered a cold start issue ( I am in South Florida) where the rpms would bounce significantly, sometimes stalling though not usually. A minute later and all was well. I will add that the around town mileage was horrible.
In November I took it to my BMW only mechanic who smoke tested it, replaced the valve cover and ccv hoses and actuator. It didn't fix the cold start fluctuations in idle or gas mileage though it stopped stalling.
This past week I myself cleaned the cam positioning sensors which weren't very dirty,
I cleaned and switched places regarding my vanos solenoids.
I removed, cleaned and put new orings on my fuel injectors.
I changed my oil and filter.
I believe my poor gas mileage around town is much improved and the car is running crisply.
But, the now improved cold start, is not perfect.
I also cleaned a Bremi MAF sensor in there but no, fully cold start since.
Any ideas guys?
Your skill and experienced is greatly appreciated.
Scott in Fort Lauderdale

[Cal122]

Have you ever checked the Vanos filters as part of your maintenance history? I'm planning to check/change them on one of my cars that has a slight stumble on cold start idle (It's fine after the car warms up). They're about $30 each, so I figure if I'm going to take them out to check I may as well just replace them. My theory is if it only happens when motor oil is cold, maybe the screens are restricting oil to the vanos solenoids which then clears up once the oil and car heat up.

[scottjeffrey]

I have last week. Then forgot. You have reminded me of them, I was looking earlier in the week. Ok, project for next weekend. You mean the two 'check valves'? Thank you and I find your thinking above quite sound. Can't hurt anyway.
Scott

[scottjeffrey]

[Cal122]

Originally Posted by scottjeffrey

You mean the two 'check valves'?

Yup, that's them!

[Bims328i]

I did check valves and turned out to be vanos solenoids in the long run. Go genuine if that is the case. To add, do we have a scanner to check OBD? A sub $200 investment for these cars goes a long long way folks. I keep mine in the car. Schwaben SCH10420 and you can expand it no problem.

[scottjeffrey]

Thanks!