I was heading home last night from work and noticed something odd. It was the first pretty cold night that we have had around 20-25 deg. and I took off from the parking lot like normal. When I got to the first stop light about a mile down the road I heard what sounded like the engine reving up right when I took my foot off the gas pedal. It did this as I coasted to the stop light. It also did it again at the next stop light just up the street. I thought maybe it was the heater blower, but It really sounded and felt like the engine reving. The car did not accelerate or anything, is this part of the warm up or normal? I also have the lower grill blocked but I don't see how that would make any difference.
I noticed this with our single-digit mornings and went searching to see if anyone else had noticed this (I have SG II and determined it runs RPM to 1600-2000 during these). I've noticed this when the car is cold, it is cold outside and I've turned on the heater to warm the car. Once the car coolant warms to above 130 F then the heater will go on full. I suspect the purpose is to continue to heat the coolant even when the car doesn't call for ICE (coasting). Once stopped the RPMs will drop down to the 1280 idle speed. I cannot recall, but I think that this behavior stops if you shut down the interior heat.
