CALPAK (was: Broadcast codes...)

[Ludis Langens]

bruce plecan <nacelp at bright.net> wrote:
>If the 1227747 is used in 4.3s, 5.0s, 5.7s, and 7.4s with the same prom but different
>injectors, and use the same calpaks for all but the v-6, and if the calpak is for
>limp home, and other misc itmes, how does the ECM figure the timing.  I would 
>think that the calpak does have the info that tells the ECM the number of cylinders.
>   Maybe it was just the combination that I was running, but in the quest for HP
>I tried a v-6 calpak, and it sure seemed down on power.

Here's what's inside the CALPAK (# 16044802) for my car:
(Use a mono-spaced font to view this.)

+------------ Z1-16  (to VCC)
|
+- 20Kohm --- Z1-15  (to RFD chip)
|
+- 17Kohm --- Z1-14  (to RFD chip)
|
+- 105Kohm -- Z1-13  (to RFD chip)
|
+- 1Kohm ---- Z1-12  (for CALPAK installed detection)
|
|     <NC> -- Z1-11  (NC)
|
+- 200Kohm -- Z1-10  (to CRANKING detection RC timer)
|
+- 440Kohm -- Z1-9   (to CRANKING detection RC timer)
|
+- 100Kohm -+------------- Z1-8  (to RFD chip)
|           |
|           +- 14Kohm ---- Z1-7  (to GND)
|
+- 310Kohm -+------------- Z1-6  (to RFD chip)
|           |
|           +- 20Kohm --+
|                       |
+- 130Kohm -------------+- Z1-5  (to RFD chip)
|                       |
|           +- 560Kohm -+
|           |
|           +------------- Z1-4  (to GND)
|           |
|           +- 280Kohm -+
|                       |
+- 14Kohm --+-----------+- Z1-3  (to RFD chip)
|           |
|           +- 38Kohm --+- Z1-2  (to RFD chip)
|                       |
|           +- 11Kohm --+
|           |
+- 510Kohm -+------------- Z1-1  (to RFD chip)

The open ended resistor values are measured to 1% or better accuracy.  The
networked values are only good for 5% or 10%.  I need a second DMM to
measure them better.  (This is a wonderful "black box" circuit lab project!)
The network arrangement may look strange, but it essentially matches what
the Iron Duke ECM does with seperate SMD resistors.


RFD stands for Redundant Fuel Device.  It is a 28 pin DIP.  It has two
functions in life:  Turning on the fuel pump relay (n seconds at key-on and
also whenever there are timing reference pulses.)  And merging the several
injector signals (it's own limp-home mode signal, and the sync and async
signals from the digital timer chip) into one injector control signal.

The RFD can sense the TPS, MAP, and CTS sensors.  The cranking detector
feeds to the RFD (the digital side of the ECM does it's own cranking
detection.)  A crank reference signal is input to the RFD.  And finally,
the RFD contains the "limp home mode / computer operating properly" timer.

When not in limp-home mode, only the fuel pump control portion of the RFD
is doing anything (the sync and async injector signals are ORed and sent
out to the injector drive transistors.)

The ECM's CPU has no inputs with which to watch on any of the RFD functions.
The only CALPAK resistor it can sample is the "installed jumper" at Z1-12.
Thus none of the fancy resistor chains can specify anything about the
vehicle.  (Other ECMs could be different though...)


My ECM has two wiring harness inputs that select the number of cylinders.
These control a divide by 2, 3, or 4 circuit.  The CPU has no way to poll
the inputs (though it might be able to deduce the division ratio because
it can detect the frequency before and after the divide circuit.)  Perhaps
the 747 jet, er ECM, gets these inputs from unused resistor locations in
the CALPAK (instead of via the wiring harness.)  But wait - the 747 is a
TBI ECM, it doesn't need the divide circuit at all.


Hmmm, an RFD chip would make a really simple single chip analog EFI system
for anyone that figures out what all the resistors calibrate.  Several
people have wished for something like this in the archives.

                   unsigned long BinToBCD(unsigned long i) {unsigned long t;
Ludis Langens         return i ? (t = BinToBCD(i >> 1), (t << 1) + (i & 1) + 
ludis at netcom.com                 (t + 858993459 >> 2 & 572662306) * 3) : 0;}