All the auxiliary air regulator does is bypass the throttle when the
engine is cold. This allows additional air thus raising the idle speed
slightly. There is a heating element in it to warm it up causing it to
close as the engine warms. Engine heat will keep it closed during warm
re-starts. It does not affect fuel mixture. Has the same effect as
holding the accelerator down slightly. The thermo-time switch mentioned
below does not go to the CPU at all. It strictly operates the cold start
valve directly, (after-thought?). It is wired to the starter circuit,
usually a second contact on the starter solenoid. When the engine is
cranked at 45f or below, it will open the valve until the heater within
it opens the switch. It is extremely important to have this thing wired
correctly. Switching the two wires going into will keep it from working.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Stan Wilder
Sent: Sunday, December 30, 2001 7:30 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Understanding AFC fuel injection--question

There is a little plastic covered sensor in my AFM. It measures air temp
passing through the AFM.
When the engine is cold, the fuel pump switch is closed inside the AFM
cover. When the engine starts the fuel pump control is passed to the
double regulator (opens the AFM fuel pump switch) when the flapper in
the
AFM opens from intake vacuum. If your thermo time switch (activates a
time sequence in the CPU) is working properly it opens the cold start
valve when you're cranking a cold engine closes the axillary air
regulator (allows the spring to close it) when the temp sensing is
passed
to the AFM (after the timed delay) . From then on the AFM runs
everything
in combination with the double relay and the vacuum assist if you've got
proper vacuum.
If I'm not correct I'll sure be willing to listen.

Stan Wilder
83 Air Cooled Westfalia

On Sun, 30 Dec 2001 18:33:27 -0500 Adam Puzerewski <VGONMAN@MSN.COM>
writes:
> 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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