I am quite sure the ECU control the injectors via ground closure
arrangement. That means one side of the injector is wired to 12V and the
other side connected to the ECU switching transistor. Early injectors
till about 78 has external current limit resistors but these are later
became an integral part of the injector.

When you monitor the injector with an oscilloscope you want to look for
the low time of the pulse. The low time of the pulse is when the
injectors are open. This should be very close to 0 volt.

According to my book it shows the voltage is around 4V when the injector
is open. I will however interpret this with a grain of salt as I think
it depends which Bosch system and what year (Digifant is derived from
the Bosch system specifically for VW).

- Vince

http://gipsyflies.home.comcast.net
1989 Vanagon GL Camper
1993 Mazda Miata (for sale)
1996 Land Rover Discovery
2005 Mini Cooper S

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of tabe johnson
Sent: Wednesday, September 01, 2004 4:55 PM
To: vanagon@GERRY.VANAGON.COM
Subject: What voltage do injectors need to fire?

With the Digifant system, does anyone know what
voltage the ECU sends to the injectors to get
them to open?  I'd need an oscilloscope to measure
this and sadly I'm without.

Thanks!

--tabe johnson
xtabe@yahoo.com
Vancouver, BC

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