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Join Date: Mar 2008
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I don't know if this help, but you can check your coolant temp from instrument cluster secret menu so you have a clue whats the temp. What i know about the fan function is that the speed is influenced by coolant temp and pressure in AC-system.
What comes to idle raise to 900rpm i noticed last winter when my battery was low on charge, car charged the battery more frequently and allmost everytime when i was on traffic lights. After i charged my battery the rpm raise went away. I think this is one factor which will cause the idle raise. Other thing is that when the engine is cold there is cat heating procedure. This will also raise the rpm but it goes away when engine reached 78-79C operatign temp. I bet there is more reasons for the idle raise but i don't have clue what...
BMW E61 ///M5 -07
Ex. BMW E39 ///M5 -01
Current mods: Short shifter, Custom clutch stop, Alpha-N + Power tuning by Evolve, AP coilovers, HEL brake lines.
Last edited by J.R ///M5; 15th May 2019 at 12:53 PM.