09-06-2020, 01:40 AM | #1 |
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Surging/Vibration with AC on
Rough Idle on B58 with A/C on
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. |
09-06-2020, 01:38 PM | #4 |
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"Violent surging"? It's hard to envision this without rpms shooting up. That's not the case, right?
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09-06-2020, 02:28 PM | #5 |
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My 17 M240 had the same issue, at idle. Ended up being a warranty issue twice and they had to work with techs in Germany to remedy the issue.
Are you losing A/C cooling abilities? Mine did. Air was only slightly chilled and then went straight room temp. |
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09-06-2020, 02:58 PM | #6 |
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09-06-2020, 02:59 PM | #7 | |
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No cooling loss. Just runs rough with it on while it’s hot out and the car’s intake temps exceed 145-150f. That’s when I notice it start to occur. |
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09-06-2020, 03:00 PM | #8 |
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09-06-2020, 03:17 PM | #9 | ||
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09-06-2020, 03:31 PM | #10 |
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I had an issue lime this in my n20, so it could be different. issue was caused by refrigerant pressure being too high. sounds like what might be happening based on only occurring in hight temps.
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09-07-2020, 07:45 PM | #11 |
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09-07-2020, 07:48 PM | #12 | |
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I'll do that - also, my powertrain warranty is voided due to tuning. And no, the tune didn't cause this issue, it's been here since I bought the car. Do you think the aspect of them looking at my compressor/evap would be affected by this void? Obviously if I blow a turbo it's not covered, but what about the A/C system specifically? |
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09-07-2020, 08:55 PM | #13 | |
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09-16-2020, 07:54 PM | #14 | ||
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