Digifant

[Franz, Paul]

Stefan Holzmann

Your english is better than my german.  Possibly you can help me with that
function later. 

I know nothing about the digifant.   However,  I will attempt to answer a
couple of questions.

1) Cam Sensor.  You only want one tooth for the detection of the Cam
position at TDC of cylinder 1.  The others might be useful to keep a
frequency lock,  but all the systems I would with are looking for one pulse.
Also the hall sensor created a Positive ramp, fast negative transition and
then a ramp back to zero as the sensor reads the tooth.  Use the fast
negative crossing for your index signal.  It leads to less error.
2)  It is common for injection to be continuous or port injected into the
manifold.  The fuel is injected into each port 4 times.  in Fact most
controls are semi-sequential with injection happening twice during the
cycle, once prior to intake, and once 360 degrees away.  This is done to
save money.  Very few production systems use a  full-sequential system.  You
will need to follow the same pattern,  or you will need to size new
injectors if you are designing a full-sequential system. 
3)  Typically most Crank sensors use 60 tooth per Revolution.  If it is
mounted to the cam, then you will need 120 teeth per cam revolution.  VW,
BMW and MB all use different numbers.  Just to make life difficult.  Use
what ever is available.  

How are you planning on programming the fuel/ignition timing sequences? What
control strategy are you going to use?  

Paul Franz


-----Original Message-----
From: Holzmann Stefan [mailto:Holzmann.Stefan at gmx.at]
Sent: Monday, September 25, 2000 2:49 PM
To: DIY_EFI at lists.diy-efi.org
Subject: Hi I'am new to the List and have a few questions


Hi
My name is Steve I'am from Austria and I'am interested in build my own EFI.
:-)
The Hardware I use is a 80C815 8 Bit Siemens Microcontroller with 32 K of
RAM and 128k of Flash. The Clock is at 12 MHz.
 Features of the Controller are:
1) eight 10 Bit ADC's
2) two "normal" timer (like the 8051 or 8031)
3) a third timer witch have four additional 16 Bit Register. This Register
can be used for capture and comparator Function's to the running timer.
4) a seriel Port

Also I have al littel LCD connected to the Controller.

To test the software I use the AT89x4051controller from ATMEL. Because it's
cheap an have an 4KB Flash on the Chip.
What Power stage to drive the Ignition and the Injector valves i use I don't
now at this Moment. There are very nice Plans on the DIY-EFI and the EFI322
website.

Now I'am working on getting up my Sotware on the Controller.
As model I use the software from the EFI322 and Al Lippers ECO 6.
But I think I will programm the quite Software in Asembler.

The system should run in near future on an VW Golf II G60 and an VW Golf II
VR6 2.9L.

Now I have my first questions:
1) I know that the G60 engine have a Digifant ECU. The Digifant determine
the position of the camshaft by the Hall Sensor of the Ignitiondistributer.
The weel wich runs into the Ignitiondistributer have not many Teeth and so
the position of the Camshaft can not be calculated so exactly than a Sensor
on the Camshaft. Is it possible to buil in an sensor at the Camshaft? And
were I can get a sensor that fit into?

2) I have seen a wiring diagram of the Digifant ECU. And I wonder why all
Injector valves are only conected to Ground and at the other side to one
wire that runs to the ECU. Opens the Digifant always all four Injector
Valves when it wants tho inject gas to one cylinder?

3) How much teeth have the weel on the camshaft of a VR6 2.9? Are there 58
Teeth an two lost teeth?

4) When I use an LM1815 to convert the signal from the Hall sensor to a TTL
Pegel. I get a Signal that looks like this
||||||||||||||<gap>|||||||||||||||<gap>||||||||||||||| ! Can anyone give me
the information how great is the duty cycle of the Signal. I mean an normal
periode without a gap.

I hop anyone can help me.

And finally excuse my bad English .-)

MfG
Stefan Holzmann
Holzmann.Stefan at gmx.at

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