I think it's related to the brake booster also. The AC is bumping the idle a bit (due to the extra load with the compressor on) and that is probably enough to mask the problem.
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2008 IB E92 M3| BBS | KW | Arkym | Platte Forme A.G. | Active Autowerke | K&N | Fabspeed | Dinan | Evolve-R
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