[Diy_efi] Jetronic

Tue Feb 28 04:48:55 UTC 2006

  Anyone remember the old D-Jet system?  It was the grandfather of our
modern speed-density systems.  Had a fascinating magnetic / mechanical
pressure transducer for measuring density; and sets (yes- setS) of breaker
points (early version) for the speed sensor! Electronic ignition, but points
for the EFI... Leave it to Bosch!    The throttle switch would pulse on and
off as the throttle moved open and create extra injector pulses for
pumpshot.   The ECU was fully analog.  There ARE people who re-map these
units by changing resistors, etc.
  I saw one of these on an older Mercedes V8. It was an early 70's model
IIRC.   I'm not the type to scrap a unique system like this if there is any
hope.  I would try to repair if feasible, but if not, it would sure be
tempting to install a Delco 1226869 (or similar).  The distributor had a VR
pickup directly compatible with an HEI ignition module. You could hull out
the transducer, and there might be enough room inside to "hide" a modern
Delco MAP sensor.  The injector impenence would be an unknown, as would be
mounting the TPS.  After taking the time to develop a good calibration;
you'd have quite a system.  It would appear to be original, but with the
advantage of fully mapped fuel and ignition.
  Fun to think about anyway!
David

----- Original Message ----- 
From: "Bill Washington" <bill.washington at nec.com.au>
To: <diy_efi at diy-efi.org>
Sent: Monday, February 27, 2006 5:11 PM
Subject: [Diy_efi] Jetronic

> One minor addition to Torbj?rn's information:
> In the analog systems from mid 80s on there were also LE2 and LU2 - (LE
refers
> to European spec and LU refers to USA spec) and LE2 and LU2 both have
closed
> loop lambda control. The Bosch part number on my LE2 is 0 280 000 344.
> For years I have been trying to obtain a circuit of the Pinted circuit
board in
> the ECU to repair, and modify a faulty one I have, but these schematic
appear to
> have been printed on a very rare material called 'unobtanium'.
> These later LE2 Jetronic ECUs use a single printed circuit board with
leaded
> components on one side (including a couple of hybrid modules) and very
dense
> surface mount components on the other and a 25 pin connector to the wiring
loom.
> I have found one early LE Jetronic ECU schematic for a BMW on the web
> (0 280 001 310) but it is significantly different from my ECU, and is
therefore
> of little assistance....
>
> Regards
> Bill
>
> >
> > Subject:
> > Re: [Diy_efi] Motronic hacking...
> > From:
> > Torbj?rn Forsman <torbjorn.forsman at gengas.nu>
> > Date:
> > Sun, 26 Feb 2006 23:55:41 +0100
> > To:
> > diy_efi at diy-efi.org
> >
> > To:
> > diy_efi at diy-efi.org
> >
> >
> > It is not very precise to call an injection system "Jetronic". This is a
> > brand name that Bosch uses for all systems that only deal with fuel
> > injection, not ignition.
> >
> > Analog systems are D-jetronic (manufactured from about 1969 to 1974),
> > L-jetronic (1974 to mid-80's), most LE-jetronic (1981 to early 90's) and
> > all LU-jetronic (the same as LE but with closed-loop lambda control).
> >
> > Digital systems are LH-jetronic (from early 80's to mid 90's, most of
> > them but not all have closed-loop, LH 2.4 and later have adaptive lambda
> > correction and some diagnostic features), LE3-jetronic (the last
> > non-closed loop system, the ecu is integrated in the air flow meter) and
> > Mono-jetronic (a TBI system, only used with closed-loop and adaptive
> > lambda correction).
> >
> > The K-jetronic, an all-mechanical system should also be mentioned. It
> > may have a closed-loop add-on and is then called K-lambda-jetronic. A
> > similar but newer variant is called KE-jetronic, it exists both without
> > and with closed-loop. Most KE systems are analog but the KE3 is digital
> > (and then uses an ecu that is very similar to the Mono-jetronic ecu).
> >
> > Most digital Jetronic systems use an Intel MCS-51 CPU. Either a standard
> >  8051/8031 with a separate A/D converter, or an 80535/80C535. In some
> > cases, mask programmed 8051's may be found but they more commonly have
> > an external eprom. Anyway, all PCBs are designed for external eprom so
> > it is a simple task to solder an eprom socket and the address latch in
> > place, and change the jumper for the CPU's EA signal.
> > The eprom may be socketed or soldered in place depending on requirements
> > from each car manufacturer.
> >
> > Some older LH-jetronic (in particular, LH 2.2) use instead an 8049 CPU.
> > The very earliest LH systems might have an RCA 1802, like the early
> > Motronic systems.
> >
> > The simplest way to identify a Jetronic system is to look at the Bosch
> > part number of the ECU.
> > I.e. 0 280 000 561. The first six digits tell just that it is a Jetronic
> > CPU. The seventh digit indicates the number of cylinders, 0 means 4
> > cylinders, 1 means 6 cylinders and 2 means 8 cylinders. The eighth digit
> > indicates the variant. 0 means D-jetronic, 1 and 2 means L-jetronic, 3
> > means LE- and LU-jetronic, 5 and 9 means LH-jetronic, 7 means
> > Mono-jetronic and 8 means K-lambda and KE. The two last digits are a
> > leap number.
> >
> > So, when asking about a "Jetronic" system, be sure to include the
> > variant of the system. I.e. mention that you have an LH 2.4 with
> > closed-loop.
> >
> > Best regards
> >
> > Torbj?rn Forsman
> >
>
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