With the early (pre-TDI) VW Diesels, the pull knob on the dash had two functions- increase the idle speed for cold idling, and it also advanced the injection timing to assist starting. However, the MB "turn-key" knob on the dash only serves to increase the idle. I wonder why MB didn't include the timing advance also?

The VW system was kind of neat. As instructed in the owner's manual, it should be pulled out all the way for maximum advance when cranking a cold engine, but ONLY if the temperature was above -10C. If it was colder than that, you're instructed to leave the knob all the way in, until the engine started to chug- then you would pull it out, and with the sudden advance, it would usually start right up.

Barry- with the work you've done on VW's so far, have you investigated the effect of the timing advance pull knob on your milli-volt readings?

Dave