Hi. I had exact same issues with my S2. Proper annoying. I replaced all the sensors ( coolant temp , thermo time switch and cold start valve ). Then had the whole fuel system overhauled. New injectors , fuel pump everything. Even took the metering unit off and had it set up on a test rig at KME injection. Nothing worked!!!!!


Then we blocked off the pipe from the metering unit to the oil separator and bang started first time everytime just with the key. Cold start problems can be confused with air leaks in the system. I think mine is on the brake servo. Was an expensive trial and error but at least I renewed a lot of old bits.


However I have stuck with it. Car runs great hot or cold. Quick test is to take the air box off and while someone is cranking the car, push down on the plate and see if she fires up. If so then you have an air leak possibly somewhere. KE jet is so sensitive and a slight air leak will mean not enough vacuum to force the plate down and fuel to the injectors or to the cold start valve if the engine is cold.


Hope this helps