[Bfrancom2]

I drive a 2017 BMW M240i with the B58. I‘m under warranty but have an odd issue the dealership claims they can’t find or fix and I’m looking for some insight.

The car runs fantastic, except for in warm weather with the A/C engaged. The idle is lumpy and it surges/vibrates unevenly in the cabin. The violent surging every 1-2 seconds is only super bad when it’s 100+ degrees outside and I’ve been driving the car for 15-20 min, and it’s slightly heat soaked. While some vibration is normal in any vehicle with load caused by the compressor, it is an uneven and unpredictable surging pattern. The RPMs never fluctuate, just surging felt in the cabin.

I’ve checked - AFRs, Fuel Pressure, etc all seem fine. As I stated it only happens once the car had heat soaked a bit in warm weather, maybe 10-15 minutes after starting the car.

Any idea what would be causing this? Dealer replaced the Idle control valve but that’s it. A/C system, belts, etc all inspected by bmw dealer and have no issues.

Thanks.