My 2010 R56 is doing something new to me. Last year my thermostat housing was dumping coolant so I replaced it and all has been fine since. I monitor my coolant temps via a IOS app and have found that my car generally operates between 223 - 226. Recently, I have noticed that when I go to idle the temperature will drop very quickly (as low as 200 in less than a minute). As soon as I begin driving it climbs right back up to 225. It also appears my intake temps seem consistently lower than previously.

It don't think the fans are running full time or anything like that but perhaps the thermostat is stuck open partially? Anyone have this experience or thoughts on the matter? Thanks!

 

I have seen that kind of numbers when the A/C is on Max, I thought it was programmed to do that?

 

If I put the AC on max, it dives down really quickly as well. This circumstance is without the A/C engaged at idle. That is the part that seems strange.

 

Hmm, well maybe it isn't just the MAX setting, could it be coming from the RECIRC setting on the HVAC? Part of what MAX does is change it from fresh air to recirculating. And none of this would surprise me to turn out to be some aberration caused by the way they wrote the laws for smog testing at the federal level on manufacturers,...

 

Did some further investigating and found that at cold start up idling the car doesn't go much past 105 or so. If I drive around normally it gets up to temp reasonably well although nowhere near as quick as it should be in 75 degree weather. Maybe stuck open in a low flow state?