Digijet - Digifant

[Jens Knickmeyer]

It surprised me a bit that such an amount of replies made it to the list. In '94,
I got very poor input on the VW EFI systems. So I will keep things on the
list and not deal with emails...

Some statements in reply to Bernd's posting:

Only on the later versions and with California models. The FH suffix
ones, used for engines rated from 90 to 107 bhp don't support any
diagnostics.

I forgot to mention that the VW diagnosis protocol changed during Digifant's
production. So the first Digifants have the "blink code" interface, a real PITA,
but at least error codes are easily readable with it. This interface covered
only read out of the error memory.
The later versions (at lweast since '92 as my G40 already has it) are using the
"fast bitserial transmission". (they really say so...). This is an ISO9141 based
interface, as already mentioned. It is interesting to have a close look at the
VAG1551 which is the diagnosis computer from VW. Although it was available
(at least) in '92, it includes features from ISO9141-2 (as the diagnosis protocol
does) - although ISO9141-2 came out in '94. 

Cylinder-selective knock control is available on all Digifants, not
just the supercharged ones.  This is documented in several SAE
papers presented by Volkswagen staff in the late 1980's. The
supercharged ones had boost control under persistent knock.

Not absolutety true the way you put it. You need a knock sensor to do knock 
control with the Digifant, and e.g. the 33kW/40kW/55kW Polo MK3 engines (or 
for European readers: Polo 2F) have no knock sensor. It is true, indeed, that the 
Digifant ECUs have the filter hardware built in, anyway. That's what I meant with the 
"modular system" - they have basically one hardware and applicate it by simply 
changing software (and maybe peripheral components).

In addition to Bernd's list of papers, I cite the literature list from my homepage:

---------------------------------------
Digifant, ein zukunftsweisendes Konzept zur Steuerung und Regelung eines Ottomotors
VDI-Berichte Nr. 612

Volkswagen's new 1.3l High-Performance SI-engine supercharged by the Volkswagen G-Lader
Kuck, Fleischer, Schnorbus
SAE Paper 860102

European an US engine design concepts after introduction of unleaded fuel in Europe
Meyerdieks, Reineck, Urbansky, Thoms
SAE Paper 861586

ABUS - ein Multimaster Bus-System
Dr. Krei?ig, Dr. Strau?, Pelz
IAM-Forum Nr. 13, 1990

ABUS und Diagnose
Hartwig
Impulse Nr. 8, Volkswagen AG, Wolfsburg 1988

---------------------------------------

NOTE: Do not take the papers too seriously! IMHO, you have to be careful with what VWsays on 
conferences etc. According to such papers, Digifant would use ABUS - one pitfall which costed me 
a lot of time until it turned out that ABUS is not used in the ECUs (BTW, does anyone know an ECU 
which uses ABUS??).

I am currently working on an English version of my homepage with information about the Polo's ECUs
what means Digijet and Digifant. So far the good news. Bad news is that it will be the same bad
English I produce here :-))

Jens Knickmeyer

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