Bosch D-Jetronic

[Stowe, Ted-SEA]

I had a d-jet on my 914's , I used to time trail one at sears point. there
is one outside in my 72 Saab 99.
 
I eventually built a 8051 replacement, but the original system was quite
capable, I've heard stories of guys putting roll bars in 914's and drilling
into and through the ECU and the car still ran, makes you wonder.
 
I have never seen a complete schematic, however there was a subset of d-jet
ECU's that had a mixture adjustment control on the ECU, also I have found
that old temp sensors generally didn't work, also the points used in the
distributor should be checked out. I used to disconnect the inlet temp
sensor, (not the head temp sensor), this tricked the ECU into running rich.
also another trick was to drill out the plug in the external map sensor so
you could adjust that. a long time ago I vaguely remember seeing some
schematic details in one of my Porsche club archive books, I'll check and
see if I still have it. I wish I still had that 914 too.
 
Ted Stowe
 

-----Original Message-----
From: James Thomas [mailto:jtvol at dcs-chico.com]
Sent: Tuesday, May 25, 1999 6:05 PM
To: DIY_EFI at efi332.eng.ohio-state.edu
Subject: Bosch D-Jetronic


Here is a good one for you guys.  I own a Volvo Specialty Service in
California.  I am 50 years old and an old SCCA racer (used to race in
E-Production in a '58 Porsche Speedster in the 1970's).  I am completing a
new project for SCCA racing, a 1971 Volvo 142 to compete in ITB.  Pretty
much got all the tricks down.  This car is brand new from the ground up
(every nut, bolt and molecule).  Got all the latest trick ideas from my
other Volvo ITB racers that I have been helping for the last few years.  I
am planning this one to be a world beater ( if I can still drive ).  Here is
the question...I am having a problem finding a schematic of the D-Jetronic
control unit (MPC) so I can adjust the fuel mixture in different ranges.  I
don't want to mess with the head temp sensor resistance as it seems to mess
up the injection timing, got to work on the inside. Haven't gotten much from
Bosch.  Need some engineering brains who might have some thoughts on
modifying the innards of this unit.
Any thoughts out there?
James Thomas
James Thomas Independent Volvo Service