Does e53 have IAC? I'm thinking it's an altitude thing and at higher altitude the mix is calculated better at start.

What scan tool are you using?

Mine will show me atmosphere pressure, MAP, throttle position sensor and (both). I also bumped my idle speed up 25-50 Rpm.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)