>
> Dan,
> The cold idle circuit of most Bosch fuel injection systems incorporate
> an "auxillary air regulator". When you start the engine, this valve is
> open, allowing additional air (and hence gas) to be consumed by the
> engine. It is electrically operated... a 12V lead attaches to the top.
> Bedminster, NJ, USA
>
This is incorrect.  The auxiliary air regulator does NOT allow any more
gas into the engine.  It also does NOT change the air/fuel mixture being
burned by the engine.

All the air that flows through the air regulator has already been
measured by the air flow meter, and so does not change the air/fuel
mixture.

The only thing that the aux. air regulator does is provide a bypass to
the closed throttle plate when the engine is cold to help overcome th
e mechanical drag of a cold engine.  It is basically a fast idle device,
very similar to an automatic choke, except that it does not change the
air/fuel mixture.

The air/fuel mixture is determined by the computer, which notes how much
air, how cold/warm it is, how cold/warm the engine is -- then the
computer decides how much fuel to inject by varying the time the
injectors are open.  Note that the state of the aux. air regulator has
no bearing on how much fuel the computer injects.

You would be right to say that more gas is being burned when the aux.
air regulator is open but that's only because the engine is cold and the
computer notices that and sets a rich mixture.  It is not dependent on
the auxiliary air regulator itself, though.

Sean

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