Remember the old days of carburetors when you put the accelerator to the floor to set the cam before starting a cold engine?

This cam set the linkage for fast idle.

That's what warm up regulator does, i.e. lets more air past the throttle plate, same as happens when throttle is opened a bit by the fast cam.

A cold engine needs richer mixture--provided by cold start injector--and when it gets it it needs a little more air, too.

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