I'm experiencing cold start problems (1995 C36 M104 HFM), that is, the car doesn't start at the first crank as it normally does after sitting for more than 4 + hours/overnight.

The ambient temperature is about 85-F.

At the second crank, the engine catches at a low and rough 500 RPM (normal is about 900 RPM).

If I give it some gas, black smoke comes out of the exhaust, however, the idle smooths out and returns to the normal 900 RPM idle speed.

This does not happen after a "hot" or "warm" start.

Is there a "cold start" valve/injector on the M104 HFM engines ?

What's the proper diagnostic procedure ?

Thanks,
:-) neil