--- Michael Elliott <camping.elliott@GMAIL.COM> wrote:

> Wait. I got this wrong. Lemme try again.
>
> On the earlier 1.9L's there are two switches on the throttle valve. One
> closes when the foot is off the gas pedal, and the other closes when the
> pedal is floored. They are wired in parallel and both connected through
> one single wire to Pin 4 of the ECU per Bentley's 97.55. Both switches
> ground Pin 4, the ECU doesn't have any way to know which switch did it.
>
> Now if the engine is at 1500 rpm or faster and you take your foot off the
> gas, the idle switch closes, grounding ECU Pin 4. Bentley's says that
> under these conditions, the ECU shuts off fuel to the injectors (24.33).
>
> But if you /floor/ the pedal, the full throttle enrichment switch closes,
> which ALSO grounds ECU Pin 4. Bentley's tells us that when this happens
> the ECU will enrich the mixture (24.34).
>
> So taking your foot off the gas or flooring the pedal both ground Pin 4
> ... so, uh, how does the ECU know whether to shut off the fuel or to
> enrich the mixture?
>
> --
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>

My guess is the ECU reads the signal from AFM. The signal from the AFM is probably
different enough between floored and foot off.

David

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