Bosch D-Jetronic WAS: What SU stands for

[mrvette]

So those injector designs date from the 60's?...the short hose to the fuel rail
was on a 6 cyl 810 datsun i had '78.....GENE

Chris Rhodin wrote:
> 
> >From memory...  The inputs are intake air temp., manifold pressure, coolant temp., throttle motion (more later), and distributer contacts.  That's what I remember.  I used to have a book, if I find it I'll send corrections.  The throttle sensor didn't sense position it sensed motion by dragging a brush down a "ladder" of contacts, this info was used to simulate an accelerator pump.  The manifold pressure sensor was two bellows stacked to move the LVDT core, one of the bellows was sealed and provided altitude compensation, the other was piped to the plenum to measure the pressure there.  An LVDT (Linear Variable Differential Transformer) is three non-overlapping coils wrapped down the length of a tube with a moving core in the tube.  An AC signal is driven into the primary and the core position can be read off the secondaries.  I don't know the electronics required to drive and read an LVDT off the top of my head, but I do know they don't have the drift and linearity problem!
s of
> other sensors (available in the late sixties).
> 
> I popped the top off the computer once and found nothing but transistors and passive components (there may have been an op-amp in a TO-5 package too).  There were a number of resistors mounted on standoffs, apparently you calibrated by changing these parts.  Based on components I saw I would say it was equivalent to the recent 555 circuit with some additional inputs.  A one-shot triggered by the distributor whose period was controlled through some analog sensors.
> 
> The fuel injectors (one per port) looked just like the ones on my 1986 Mustang.  The big difference is the old Bosch injectors used a short hose to connect to the fuel rail.
> 
> Chris Rhodin
> chris at notav8.com
> 
> ----------
> From:   mrvette
> Sent:   Wednesday, July 08, 1998 16:29
> To:     diy_efi at efi332.eng.ohio-state.edu
> Subject:        Re: What SU stands for
> 
> just how complicated was this analogue computer?  what inputs did it use?  was
> it based on silicon technology?  use chips?   what is an LVDT?  same as a MAP
> sensor? did it have fuel injecters like what we see today?  GENE
> 
> Chris Rhodin wrote:
> >
> > My 1972 Renault R-17 had Bosch D-Jetronic fuel injection in it.  This was an all electronic (with the exception of the thermo-time switch) system that I've seen in VWs from the late-sixties.  It used an LVDT to measure the manifold pressure and an analog computer to set the pulse width, the distributor had an extra set of contacts that provided timing information to the computer.  By the mid-seventies Bosch had moved away from the electronic systems in favor of the mechanical CIS systems.
> >
> > As far as I know this is the earliest all electronic FI produced in volume (emphasis on volume).
> >
> > Chris
> >
> 
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