With the possible exception of the new direct injection cars, all cars with gasoline engines require the concept of "choke" to start when cold.

"Choke" entails a richer than normal mixture plus some extra air to deal with this.

Richer mixture is required because the fuel in the fuel-air mixture tends to leave the flow and "stick" to cold manifold surfacese, i.e. not making it to the combustion chamber.

Extra air is required because the mixture still needs to be stoichiometric.

On older carb cars this was accomplished by a choke flap and a fast idle cam.

On your fuel injected car, it's accomplished by a cold start injector plus the idle control valve. Both of these are computer (electrically) controlled based on inputs from a temperature sensor (NOT the same one that feeds temp guage).

If the air quantity is affected by vacuum leaks, this will create a problem, too.

So, it's ECU, wiring, sensor, injector, valve, vacuum.

__________________
Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles