RE: [T3] Low Voltage

["Mark Davis" <m37davis@adelphia.net>]

Thanks for the link. Good info there.

Mark-69 fastback F.I.

-----Original Message-----
From: James Montebello [mailto:lapuwali@yahoo.com] 
Sent: Thursday, June 16, 2005 12:07 PM
To: type3@vwtype3.org
Subject: RE: [T3] Low Voltage


Here is everything you ever wanted to know about the internals of D-Jet.
It's
for the 914 systems, but I'd be gobsmacked if the Type 3 systems aren't 99%
the
same, which just a few calibration values differing between them.  The MPS
does
appear to be different for the Type 3 v. the 914, in that the Type 3 MPS has
only one coil, where the 914 has two, and integrates the air temp signal,
making the MPS a true air-density meter, not just a manifold pressure
sensor.

http://members.rennlist.com/pbanders/

jamesm

--- Russ Wolfe <russw@classicvw.org> wrote:

> On Thu, 2005-06-16 at 06:14, Mark Davis wrote:
> > So that means it isn't a matter of the cold start alone, but most likely
> the
> > time the injector is on. Now you guys have done it. Prior to becoming
> > disabled I was an Engineering Technician with Electronics and Optics as
my
> > discipline. This will now bother me until I get a schematic and figure
out
> > how it works. Anybody know if one is available anywhere? From physically
> > looking at the electronics I would say there is probably a differential
> > circuit that cuts on/off based on the difference in voltage at some
point
> in
> > the circuit. If the upper extreme is lower than the design calls for the
> > transistors used to switch the voltage on/off across the coil in the
> > injectors may not be shutting off all the way allowing some small
leakage
> > current to remain across the coil causing the injectors to remain on
longer
> > than the spark remains in the chamber. Any other thoughts?
> > 
> > Mark-69 fastback F.I.
> > 
> The D-Jet FI systems is a dwell type system. The variations in
> temperature and such change the amount of time that the injector stays
> open. IIRC, it is in the range of 25-45ms.
> The ECU does not have any built in voltage regulation, and therfore is
> effected by fluctuations in system voltage.
> I think I saw a functional, hand drawn,  schematic of the ECU on one of
> the 914 web sites.
> I have it here someplace, but I think it on the hard drive of a dead
> computer.
> Our injectors are not timed exactly with the engine. They are fired in
> pairs. One of each pair fires onto an opening intake valve, and the
> other of the pair fires onto a closed intake valve.
> 
> -- 
> Russ Wolfe
> '71 FB AT
> '66 FB MT
> '64 T34 (not running)
> '65 T1 (not running)
> '05 KIA Sorento SUV
> russw@classicvw.org
> http://www.classicvw.org
> 
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