The presence of a knock sensor doesn't enter into it. Both Digifant I
and II can have knock sensors. Both I and II can also lack knock
sensors. If the compression ratio of the engine needs it it gets it,
with either system.

That Jetta Bentley shows knock sensor on both I and II. 1.8 w/10.0-1 CR
Meanwhile the Fox Bentley shows knock sensor on neither. 1.8 w/9.0-1 CR

Both types are from later cars than 86 when Vanagon Digifant came out.
I had an Vanagon 022 ECU once that said Digifant I on it. Digifant II
came out next, on the inline engines.

Why VW later confused things by calling the latest most complicated
version of the inline system Digifant I is a mystery to me.

Mark

Robert Ueltzen wrote:
> According to my Bentley for 86-92 Jetta,Golf, and GTI, the Digifant II
> has a throttle position switch, and no knock sensor like the Vanagon.
> The Digifant II also has a Hall Ignition Control Unit.  Digifant I has
> a throttle position potentiometer, an ignition coil power stage, and a
> knock sensor set up.  I believe the Digifant I system was used for the
> California cars in 1991, and 1992.
>
>