Digijet - Digifant

[David Hunt]

Could you copy me on these emails.  I'm certainly not bored.  I'm especially
interested in the simpler controllers and the cylinder specific selective
knock control.

dh



----- Original Message -----
From: "Jens Knickmeyer" <knickm at gmx.net>
To: <diy_efi at diy-efi.org>
Sent: Thursday, August 23, 2001 12:31 PM
Subject: RE: Digijet - Digifant


> Morton,
>
> Digijet was developped by Volkswagen because they needed an ECU which
could
> handle lambda control. Development started at the beginning of the 80s
because at that
> time it became clear that in Europe the cat. converters were soon to be
introduced and
> VW wanted a reliable system which couzld be easily adapted to several
cars. It is basically a
> Bosch L-Jetronic, only the ECU was designed by VW because at that times
Bosch had only
> analog ECUs and VW wanted to use a digital one. So, all peripheral
components as
> fuel pumps, fuel filters, fuel rail, injectors and sensors are L-Jet
parts. Some people call
> the Digijet "L2-Jetronic". Digijet handles only fuel injection, there is
no ignition management
> (this was done by a seperate ECU called "Dignition"). Digijet has always
been a MAF system.
> The Digijet lying next to my keyboard is based on a 8049 controller.
Firmware is kept in a
> 4k(!)-EPROM. There is no OBD or any other sophisticated features as for
example idle revs
> stabilisation. Digijet is very simple and therefore in Germany a good
choice for tuning.
>
> Digifant was developped by Volkswagen, too. In contrast to Digijet,
Digifant is a complete
> motronic system which implements injection an ignition management. The
system came out
> in the early '90s (at least in Germany). It was available as a MAF or MAP
system. The MAP
> systems were used in the cars which used the Volkswagen "G-Lader", a
mechanical supercharger
> (In America, there are even non-supercharged cars equipped with MAP
Digifants). The MAF
> systems were used in non-supercharged European cars as the Golf, Passat,
Corrado.
> Digifant was re-designed several times. Early ECUs have a 8051 for
ignition management and
> a 6909 for injection management. Later, a single 68HC11 was used for both
tasks, whereas
> the ECU still contained two boards - an analog and a digital board (the
'90 Corrado used such
> an ECU). My '92 Polo-G40 has a Digifant with only one board, and AFAIK,
this is the last
> evolution of Digifant.
>
> Features of Digifant are:
> - idle rev. stabilisation using spark timing
> - OBD which implements the Volkswagen diagnosis protocol based upon
ISO-9141
> - MAF or MAP sytems using the same hardware design
> - cylinder selective knock control (only used with supercharged engines)
>
> Coding a Digifant system is possible but takes a lot of time because the
diagnosis protocol
> takes approx. 70% of all code, and it is a hard job to identify which
parts of code belong to
> OBD and which belong to engine control.
>
>
> If you have specific questions (e.g. concerning the NZ engines and their
engine control) feel free
> to ask me via email (that way we don't bore the other 95% of the list
members which are interested
> in American/Australian engines).
>
> Regards,
>
> Jens Knickmeyer
> --------------------------------------------------------------------------
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