, I thought "cold start" mode would mean more fuel being dumped into the engine? Why would it choke?
Too much fuel "running rich" is good for getting a cold engine running however once it is up to temp it can make it splutter, be poor to start or even not start.
With regard to "choke" this is the knob you had to pull out on old cars with a carburetor to
help cold starts, It closed a flap on top of the charb barrel to reduce air intake and make the mixture rich "choking it". You knew when the engine was warm enough to push it back in when the engine spluttered and died when you pulled up at the traffic lights and wouldn't start again. You pushed the choke knob back in and it started fine.
This may have been before your time though, I've had many cars with a choke knob but then I have been driving 20 odd years.
From wiki reference choke
Automotive
A choke valve is sometimes installed in the carburetor of internal combustion engines. Its purpose is to restrict the flow of air, thereby enriching the fuel-air mixture while starting the engine. Depending on engine design and application, the valve can be activated manually by the operator of the engine (via a lever or pull handle) or automatically by a temperature-sensitive mechanism called an autochoke.
Choke valves are important for normally-aspirated gasoline engines because small droplets of gasoline do not evaporate well within a cold engine. By restricting the flow of air into the throat of the carburetor, the choke valve reduces the pressure inside the throat, which causes a proportionally greater amount of fuel to be pushed from the main jet into the combustion chamber during cold-running operation. Once the engine is warm (from combustion), opening the choke valve restores the carburetor to normal operation, supplying fuel and air in the correct stoichiometric ratio for clean, efficient combustion.
Note that the term "choke" is applied to the carburetor's enrichment device even when it works by a totally different method. Commonly SU carburetors have "chokes" that work by lowering the fuel jet to a narrower part of the needle. Some others work by introducing an additional fuel route to the constant depression chamber.
Chokes were nearly universal in automobiles until fuel injection began to supplant carburetors in the late 1980s. Choke valves are still common in other internal-combustion applications, including most small portable engines, motorcycles, small prop-powered airplanes, riding lawn mowers, and normally-aspirated marine engines
good info
