smell like rich at start up only, why?
 

Almost every time starting the car, especially after 1/2 day or longer sit, the exhaust tips throw out excessively gas smell (burned). It disappear either after I step on the pedal, or couple hundred feet max. Why?

Also, I feel like my idle is kindda low after warmed up, but I am not too worry since this is only idle. While driving, the mixture is control by the ECU. Am I correct?

The engine idle speed is controlled by the Idle Speed Control Valve (ICV), which is controlled by the dme computer, yes.
What is your car's idle speed when hot? When cold? The idle speed when both hot and cold is supposed to be 880 rpm.
When you say burned exhaust smell, you mean that there is a lot of black smoke? Or blue smoke? Blue would mean oil has entered the combustion chamber(s) of one or more cylinder.

When started the car, RPM is a little above 1k. After several seconds, it comes down to a hair line above 1 mark below 1k.

Regarding smoke color, it's normal. A little normal color smoke at start up, that's all, but the smell is excessive at start up. It smells like it's running rich. It's there even after couple seconds of driving. After couple seconds, it smell less but still there. Actually I won't smel it during the long drive after the first couple seconds, but after the drive, even though I can't smell it at the driver seat but I still can smell it when I come close to the exhaust tips. I wonder if it is controlled by the DME, is there a posibility that it's running rich, or it is only at idle?

http://forums.pelicanparts.com/uploa...1216231739.jpg

I think that sounds normal. The dme causes more gas to shoot into the engine to help it to start up. The engine needs a richer fuel mixture on start up. As long as it isn't burning rich while it's hot, you're ok. Also, your idle level sounds normal. Earlier years idle at about 80 rpm lower, but yours is ok.

If you still aren't sure, then ask Drago about performing an Italian tuneup on your 911. It'll be interesting for sure.

I did the Italian tune up, several times. I didn't see the pub of smoke as he and several others described.
Thanks Rusnak