[mrpete!]

Hey everyone,

I’ve been experiencing several issues since buying my first (used) BMW—a 2011, 320i E90 LCI, n46T—and I’d appreciate your thoughts on my diagnosis and potential solutions.

Issue:
The car has an intermittent rough idle in park and drive when the air conditioning is not engaged.

Error Codes:

• P2187 DME: DMTL pump motor activation
• P2189 DME: DMTL pump motor activation
• 2789 DME: Fuel mixture adaptation, idling, per time unit

What IÂ’ve Tried So Far:
• Cleaned the MAF sensor, throttle body plate, and differential pressure sensor
• Ran engine cleaner in the fuel tank
• Performed a smoke test on the fuel tank using a DIY smoke machine (burning baby oil in a jar):
• Sealed around the fuel nozzle with a rubber glove
• When pumping smoke into the tank, the glove inflated
• My understanding is that if there were a leak in the fuel system, the glove wouldn’t inflate—please correct me if I’m wrong
• Performed a smoke test on the throttle body and air intake system:
• Noticed smoke coming from the crankcase oil breather valve on top of the engine
• I believe this system should not allow smoke to pass through into the engine while the car is off, though I could be mistaken

My Questions:

1. Should I replace the engine rocker cover since the crankcase vent valve is located on this part?
2. Do I need to replace the entire crankcase ventilation system, including hoses and pumps?
3. Are there other areas I should investigate to resolve the rough idle and error codes?

Any suggestions or guidance would be greatly appreciated!