On the Digijet:

The ignition switch 'start' position tells the ECU to add extra fuel.

When the ignition switch is returned to the 'run' postion, the temp 2 sensor
(engine coolant temp) tells the ecu the engine is cold, so extra fuel is
added.

The aux air valve gives the engine extra air when cold, so it idles a little
higher.
The Air Flow Meter sees this extra air,and  tells the ECU, which keeps the
fuel-air ratio for a cold engine correct.

2 cents worth,
Mark Ingalls
85 GL
75 Beetle

>From: Adam Puzerewski <VGONMAN@MSN.COM>
>Reply-To: Adam Puzerewski <VGONMAN@MSN.COM>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Understanding AFC fuel injection--question
>Date: Sun, 30 Dec 2001 18:33:27 -0500
>
>Volks,
>I just spent the better part of the day diagnosing my fuel injection on my
>81 and am back where i started.
>
>I have an official vw AFC book, as well.  What I do not get is the process
>when it is starting cold.....air flows thru the AFM, and if the motor is
>cold enough, the auxillary air regulator is open, and air is diverted to
>the intake manifold, thus bypassing the throttle body.  This book says that
>this enables the motor to act the same cold as it does hot, for the control
>unit adds additional fuel to the injectors when it senses the engine is
>cold.  Now, there is no sensor, or anything on the throttle body, so how
>does this auxillary air regulator do anything?  The air still ends up in
>the intake manifold and thus diverted to the cylinders
>anyway..................I could see it doing something if it were
>unregulated air, but it is regulated at the AFm.................
>
>
>
>Adam P
>
>81 Vanagon westy ( The Brick)
>70 SingleCab "Whitey"
>74 Beetle "ol yeller"
>73 Transporter (STILL at paint shop)
>
>Used Vanagon Parts for sale (mostly aircooled)

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