The emissions system is running its air injection pump. This is normal for literally the first 35 seconds.On engine start after being shut down long enough to cool, there is a high-pitched whine that lasts for about 35 seconds, the frequency getting higher right before it stoops. Is this the vapor canister purge function or ???
These pumps have been used for decades by many, if not all, manufacturers. I have a 1977 and a 1990 Benz and both have one. Previously they were belt driven and often not very noisy. The one on the smart is electric and obviously noisier.What other manufacturers' vehicles have this emissions air pump?
Sounds like the secondary air injection pump is on its last legs. The noise will be very annoying and goes away after several seconds, but it shouldn't hurt anything. Eventually it will stop working altogether, it'll throw a code and the cel will be on.You will need to replace in order to get through your state inspection.
How would I disconnect the air injection pump? It would at least help with the diagnostics. If the sound goes away when it is unplugged and comes back when I plug it in - mystery solved.