RE: [T3] Low Voltage

[Russ Wolfe <russw@classicvw.org>]

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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